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Article

Exogenous Uniconazole Application Positively Regulates Carbon Metabolism under Drought Stress in Wheat Seedlings

by
Ying Jiang
1,
Hao Rong
1,
Qiang Wang
1,
Yingchao Lu
1,
Na Li
1,
Weiqiang Li
1,
Min Li
1,
Tao Xie
1,
Shanshan Wang
1,
Hong Zhao
1,
Yanyong Cao
2,3,* and
Yumei Qian
1,4,*
1
School of Biological and Food Engineering, Suzhou University, Suzhou 234000, China
2
Institute of Cereal Crops, Henan Academy of Agricultural Sciences, Zhengzhou 450002, China
3
The Shennong Laboratory, Zhengzhou 450002, China
4
Anhui Province Key Laboratory of Farmland Ecological Conservation and Pollution Prevention, Anhui Agricultural University, Hefei 230036, China
*
Authors to whom correspondence should be addressed.
Agronomy 2024, 14(1), 22; https://doi.org/10.3390/agronomy14010022 (registering DOI)
Submission received: 30 November 2023 / Revised: 17 December 2023 / Accepted: 19 December 2023 / Published: 21 December 2023
(This article belongs to the Special Issue Strategies for Enhancing Abiotic Stress Tolerance in Crops)
Browse Figures
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Abstract

:
Drought is one of the most detrimental environmental factors restricting the growth of wheat (Triticum aestivum L.). The investigation of the impact of uniconazole on carbon metabolism in wheat seedlings under drought stress could provide new insights into wheat stress physiology and tolerance. The effects of uniconazole (30 mg L−1) on wheat drought tolerance were investigated via a physiological analysis of the wheat genotypes ‘Wansu 1510’ (WS1510) and ‘Huacheng wheat 1688’ (HC1688) under a 15% polyethylene glycol (PEG) and 30% PEG treatment and a transcriptome analysis of ‘Wansu 1510’ (WS1510) under a 30% PEG treatment. The results revealed that uniconazole significantly increased the leaf relative water content (RWC), reduced plant height, and counteracted the reduction in fresh weight and root length under drought stress. It inhibited the excessive accumulation of reactive oxygen species (ROS) and protected against membrane lipid peroxidation caused by drought stress by regulating superoxide dismutase (SOD) gene expression, enhancing antioxidant enzymes activities, and adjusting the content of osmoregulatory compounds in drought-stressed plants. Furthermore, uniconazole treatment increased chlorophyll (Chl) and carotenoid (Car) contents, inhibited the increase in sucrose concentration, and alleviated the reduction in starch content due to increased sucrose synthase (SS) activity under drought stress. Transcriptome sequencing revealed that uniconazole regulated the expression of genes associated with starch and sucrose metabolism, porphyrin and chlorophyll metabolism, the photosynthetic antenna proteins, carotenoid biosynthesis, and carbon fixation in photosynthetic organisms, which are involved in carbon metabolism processes and photosynthetic pigment production and which regulate the conversion of sucrose and starch under drought stress. Our findings emphasize the importance of exogenous uniconazole in regulating carbon metabolism in wheat.

1. Introduction

Drought stress is considered one of the most detrimental abiotic stresses, severely impacting plant growth and development, that limits agricultural production, erodes global food security, and threatens sustainable plant development [1]. Drought stress affects growth rates, photosynthesis, membrane integrity, oxidative stress responses, osmotic adjustment, and carbon metabolism through phenotypic changes and as a result of adaptive stress responses [2]. Drought stress can damage the root system, prevent plants from absorbing water normally, reduce plant height, cause leaf stomatal closure, and reduce the leaf relative water content, thereby affecting plant photosynthesis [1,3]. Drought stress results in ROS production and cellular metabolism by-products generated during photosynthesis and respiration processes [4]. Plants mitigate cellular damage caused by ROS accumulation by producing osmotic regulatory substances that enhance the plant’s osmotic potential, root water absorption capacity, and the antioxidant constituents that balance ROS metabolism [1,5]. However, this self-regulatory capacity of plants is finite. Severe drought stress can disrupt the integrity of chloroplasts and inhibit photosynthesis due to oxidative damage. Photosynthesis directly affects carbon metabolism, which becomes unbalanced by drought stress, reducing carbon assimilation [6]. Drought stress results in stomatal closure, which reduces carbon absorption and affects photosynthetic carbon fixation [7]. Many studies have demonstrated that enhanced carbon absorption and sugar accumulation could improve reactive oxygen radical scavenging and stabilize biological membranes to protect plants from stress damage [7,8].
Wheat (Triticum aestivum L.), a major world grain crop, is a prominent source of carbohydrates and proteins [9]. The northern region of the Anhui province is the main wheat-producing area and one of the suitable areas for wheat cultivation. Drought occurs frequently during the winter wheat growth life cycle driven by global climate change, which causes water shortages in the plant, influences functional leaves’ senescence, and finally leads to considerable yield and quality loss [10]. In addition, drought dramatically affects mineral availability in soil and causes disturbance in the nutrient balance in wheat plant tissues [11]. Because of this, exogenous compounds, chemicals, and plant growth regulators have been developed to alleviate the adverse effects of drought on plants [12].
Uniconazole, a triazole plant growth retardant, has been proven to enhance the resistance of a wide range of abiotic stresses in various plants, such as chilling stress in mung bean [13], drought stress in soybean [14], shading stress in japonica rice [15], waterlogging stress in soybean [16], lodging stress in wheat [17] and buckwheat [18], salinity stress in barley [19] and heat stress in rape [20]. Based on the results of these studies, exogenous uniconazole improved growth parameters, alleviated cellular injury, protected the photosynthetic machinery, increased carbohydrate content, enhanced the osmotic adjustment capacity, and strengthened antioxidant defense mechanisms under stress. Above all, uniconazole has key functions in the regulation of endogenous hormone levels. Research has shown that uniconazole inhibits gibberellin (GA) biosynthesis through ent-kaurene oxidase, which promotes the three-step oxidation of ent-kaurene to ent-kaurenoic acid [21]. Moreover, uniconazole, as an inhibitor of ABA 8′-hydroxylase, affects abscisic acid (ABA) catabolism [22]. Uniconazole also enhances cytokinin (CTK) biosynthesis, playing a fundamental role in improving plants’ chlorophyll (Chl) content, photosynthesis, and yields [23]. Furthermore, uniconazole has also been shown to regulate the NAC and TCS gene expression levels, improving drought tolerance by enhancing soybean plants’ physiological state [14]. In addition, transcriptome analyses, performed to identify the molecular mechanisms of uniconazole actions, revealed differentially expressed genes (DEGs) in a wide range of metabolic pathways, regulating the corresponding physiological characteristics in duckweed [24], soybean [21], and industrial hemp [25] plants.
In recent years, significant progress has been made in understanding the role of uniconazole on stress responses in wheat plants. Uniconazole dramatically improved the mechanical strength of winter wheat plants, enhancing lodging stress tolerance [17]. Conjoint analysis of physiological and multi-omics data demonstrated that exogenous uniconazole combined with maize straw mulching improved dryland winter wheat’s tillering ability and yield [23]. Uniconazole alone or in combination with manganese markedly improved winter wheat’s antioxidant defense system and grain yield in semiarid regions [26]. However, uniconazole’s regulatory role in wheat plants’ carbon metabolism under drought stress remains unclear. The current study determined the photosynthetic pigment content, carbon metabolism indicators, and wheat plants’ antioxidant defense system after treatment with uniconazole under drought stress. The expression trends and functions of DEGs related to carbon metabolism in drought-stressed plants treated with uniconazole compared to drought stress alone were explored and analyzed. The results of the present study provide significant insights into the regulatory mechanism of uniconazole in relation to carbon metabolism in wheat plants, which can contribute to increased drought stress tolerance.

2. Materials and Methods

2.1. Plant Materials and Stress Treatments

Wheat seeds of the cultivated varieties, ‘Wansu 1510’ (WS1510) and ‘Huacheng wheat 1688’ (HC1688), were selected for uniformity, sterilized with 2.5% sodium hypochlorite for 10 min, and repeatedly washed three times with water. Wheat seeds were immersed in (a) distilled water and (b) 30 mg L−1 of uniconazole [17] for 12 h, and the seeds’ surfaces were then thoroughly rinsed with water. Soaked seeds were placed flat in seedling boxes (length × width × height: 32.5 cm × 24.5 cm × 4.5 cm) containing 1/2 Hoagland nutrient solution. The seedling boxes were placed in an artificial illumination incubator at 22/15 °C, 14/10 h day/night, and under a relative humidity of 65–70% at Suzhou University. PEG was used to simulate drought stress. After 18 days of growth, wheat seedlings were irrigated as follows: (1) a + 0% PEG (CK), (2) a + 15% PEG (P15), (3) a + 30% PEG (P30), (4) b + 0% PEG (S), (5) b + 15% PEG (SP15), (6) b + 30% PEG (SP30). Wheat seedling leaves (three replicates from each treatment) were harvested after 72 h of drought stress treatment and were used for physiological analysis. The wheat seedling leaves of ‘Wansu 1510’ in the P30 and SP30 treatments were randomly sampled and stored at −80 °C for transcriptome analysis.

2.2. Growth Parameters and Relative Water Content (RWC)

Plant height and root length were measured with a ruler. Five plants were randomly selected for fresh weight (FW) measurement. The relative water content (RWC) of wheat seedling leaves was determined as follows: RWC (%) = [(FW − DW)/(TW − DW)] × 100, where FW is fresh weight, TW is turgid weight, and DW is dry weight.

2.3. Photosynthetic Pigments and Carbon Metabolism-Related Indicators

Photosynthetic pigments were measured following the modified procedure of Arnon [27]. A total of 0.1 g fresh leaves were immersed in ethanol (10 mL) and placed in the dark for 24 h. The absorbance at 663, 645, and 470 nm was measured in the resulting solution to determine the total chlorophyll (Chl), Chl a, Chl b, and carotenoid (Car) contents, respectively.
Carbon metabolism-related indicators were determined using the corresponding reagent kits produced by Beijing Solarbio Science & Technology Co., Ltd., Beijing, China. Specifically, a Sucrose Content Reagent Kit (Cat#BC2460), Starch Content Reagent Kit (Cat#BC0700), and Sucrose Synthase (SS) Activity Reagent Kit (Cat#BC0580) were used to measure relevant indicators spectrophotometrically. An SS activity unit was defined as the catalytic production of 1 μg sucrose per minute per gram of tissue as monitored at 480 nm.

2.4. ROS Accumulation and Membrane Lipid Peroxidation

Hydrogen peroxide content was assayed using the potassium iodide technique following Sergiev et al. [28] with a slight modification. Superoxide anion content was measured according to the hydroxylamine oxidation reaction of Elstner and Heupel [29].
Approximately 0.5 g of wheat samples were ground with liquid nitrogen, and then 5 mL of pre-cooling phosphate buffer (pH 7.8) was added and mixed well. The homogenate was centrifuged at 10,000× g at 4 °C for 20 min, and the supernatant was used to determine malondialdehyde (MDA) content, soluble protein content, and antioxidant enzyme activities. MDA content was determined using the thiobarbituric acid method described by Dionisio-Sese and Tobita [30] with some modifications.

2.5. Antioxidant Enzyme Activity and Osmoregulatory Compounds

Superoxide dismutase (SOD) activity was measured with the nitrogen blue tetrazole (NBT) photoreduction method of Giannopolitis and Ries [31] and expressed as U g−1 FW. Peroxidase (POD) and catalase (CAT) activities, represented as U min−1 g−1 FW, were determined with the guaiacol method via ultraviolet (UV) spectrophotometry following the protocols of Choudhary [32] and Beers and Sizer [33], respectively. One unit (U) of POD and CAT activity denoted the absorbance value changes per minute as detected at 470 nm and 240 nm, respectively. Ascorbate peroxidase (APX) activity was estimated following the protocol of Cakmak and Marschner [34] and was expressed as μmol min−1 g−1 FW.
Based on the technique of Monreal et al. [35], the soluble protein content was determined using a slightly improved Bradford method. Proline (Pro) content was measured with the sulfosalicylic acid method in accordance with Bates et al. [36].

2.6. Total RNA Extraction and Transcriptome Sequencing

Total RNA was extracted from wheat seedling leaves ‘Wansu 1510’ under P30 and SP30 treatments using TRIzol® Reagent according to the manufacturer’s instructions. Then, RNA quality was evaluated using a 5300 Bioanalyser (Agilent, Santa Clara, CA, USA) and ND-2000 (NanoDrop Technologies, Wilmington, DE, USA). High-quality RNA was screened and used to construct a sequencing library.
cDNA library preparation and sequencing were performed following the manufacturer’s instructions (Illumina, San Diego, CA, USA). Firstly, mRNAs were isolated by oligo(dT) beads according to the polyA selection method and then fragmented using a fragmentation buffer. Secondly, double-stranded cDNAs were synthesized with a SuperScript double-stranded cDNA synthesis kit (Invitrogen, Carlsbad, CA, USA) using random hexamer primers (Illumina). End-repair, phosphorylation, and ‘A’ base addition were performed in the synthesized double-stranded cDNAs following the library construction protocol of Illumina. Subsequently, library size selection was conducted to capture cDNA target fragments of 300 bp to remove unwanted cDNA fragments and contaminants, followed by 15 PCR amplifications with the Phusion DNA polymerase (NEB). Finally, cDNA library preparations were sequenced on an Illumina NovaSeq 6000 platform at Shanghai Majorbio Bio-pharm Biotechnology Co., Ltd. (Shanghai, China) after being quantified by Qubit 4.0. All raw sequencing reads were submitted to the NCBI database with series number PRJNA1009004.

2.7. Quality Control and Transcriptomic Data Analysis

High-quality clean data were obtained to ensure smooth subsequent analysis by filtering raw reads with fastp tools [37]. The high-quality clean reads were mapped to the wheat reference genome sequence (http://plants.ensembl.org/Triticum_aestivum/Info/Index, accessed on 29 November 2023) using HISAT2 [38] software. Each transcript expression level between the two different samples was calculated using the Fragments Per Kilobase of transcript per Million mapped reads (FPKM) method. RSEM [39] software was used for quantitative analysis of gene expression. DESeq2 [40] software was used to analyze gene expression differences between samples. The screening criteria for differentially expressed genes (DEGs) were as follows: false discovery rate (FDR) <0.05 and |log2FC (fold change)| ≥ 1. Enrichment analysis of the DEGs was performed to elucidate their functions, with GO (Gene Ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes) performed for biological function classification and significantly enriched metabolic pathway analysis. GO functional enrichment and KEGG pathway analysis were performed on Goatools and KOBAS [41], respectively. Functional enrichment analysis was conducted using Fisher’s exact test, and multiple tests were conducted using the BH (Bonferroni, Holm, Sidak) method with a corrected p-value ≤ 0.05.

2.8. Quantitative Real-Time PCR (qRT-PCR) Validation of RNA-Seq Data

Gene-specific primer sequences were designed with Primer Premier 5 software, listed in Table S1. The wheat actin-2 gene was chosen as the reference gene. The template was the total RNA from the same sample used for RNA-Seq analysis, extracted and purified as mentioned above. cDNA was synthesized using a FastKing RT Kit (Tiangen BioTek, Beijing, China). Quantitative real-time PCR reactions were performed using Power qPCR PreMix (Genecopoeia, Rockville, MD, USA) in a 20 μL volume containing 10 μL cDNA and 10 μL qPCR Mix with the target gene primers. The reaction protocol was as follows: 95 °C for 10 min, 40 consecutive cycles at 95 °C for 10 s, and 60 °C for 40 s. Gene expression levels were calculated using the 2−ΔΔCT method. Three independent biological replicates of each sample were assessed.

2.9. Statistical Analysis

Graphs were drawn using GraphPad Prism 8.0 software. SPSS v20 software was used for the analysis of variance (ANOVA) between treatment groups, and experimental data are represented as mean ± standard errors. Significant differences were detected using Duncan’s multiple-range tests (p < 0.05).

3. Results

3.1. Growth Parameters and Relative Water Content (RWC)

The exposure of wheat plants to drought stress (by PEG dehydration simulation) adversely affected plant growth parameters and RWC. A significant reduction was observed in the plant height of WS1510 and HC1688 under 15% PEG (P15) and 30% PEG (P30) treatments. Similarly, the root length, fresh weight, and RWC of WS1510 and HC1688 were lower under drought stress than the control (Figure 1). Exogenous uniconazole application further reduced the plant height of WS1510 (by 45.5–50.4%) and HC1688 (by 26.3–49.3%) wheat seedlings under drought stress, compared to the PEG treatments (Figure 1B). On the contrary, uniconazole treatment under drought stress significantly increased root length by 22.3–82.1% and 49.0–52.3% in WS1510 and HC1688, respectively, when compared to drought treatment alone (Figure 1C). Similarly, exogenous uniconazole application significantly increased fresh weight by 24.6% in WS1510 under the P15 treatment and by 28.9% in HC1688 under the P30 treatment, compared to the PEG treatment alone (Figure 1D). The RWC of SP30-treated wheat seedlings was dramatically increased by 21.3% and 27.4% in WS1510 and HC1688, respectively, compared to the P30-treated seedlings (Figure 1A).

3.2. Photosynthetic Pigments and Carbon Metabolism-Related Indicators

As drought stress intensity increased, the photosynthetic pigment content declined compared to that in the CK. There was a sharp decrease in the Chl a and total Chl contents of WS1510 and HC1688 under the P30 treatment, compared to those in the CK (Figure 2A,C). Similarly, the Chl b and Car contents were reduced by drought stress, although no significant differences were observed in WS1510 (Figure 2B,D). Compared to the PEG treatment alone, uniconazole application raised the Chl content of wheat leaves under drought-stress conditions. Specifically, SP30 significantly increased the Chl a content of WS1510 by 16.9%, and it also obviously increased the total Chl content of WS1510 and HC1688 by 13.3% and 5.7%, respectively, compared to those in the P30 treatment (Figure 2).
Drought stress significantly increased the sucrose content, notably decreasing the starch content in wheat seedling leaves (Figure 3A,B). Compared with CK, PEG treatments sharply increased the sucrose content by 1.7- to 3.0-fold in WS1510 and 8.7- to 15.9-fold in HC1688. The starch content of drought-treated WS1510 and HC1688 plants was significantly reduced by 3.6–5.6% and 10.9–18.1%, respectively, compared to that in the control. Uniconazole treatment under drought stress significantly ameliorated the increase in sucrose content and mitigated the decrease in starch content relative to the non-uniconazole-treated plants. Different drought severities prominently repressed the SS activity compared with that in non-drought-treated plants (Figure 3C). On the other hand, exogenous uniconazole application notably increased SS activity. SP30 increased the SS activity of WS1510 by 55.0% and that of HC1688 by 15.7%, respectively, compared with P30 treatment.

3.3. ROS Accumulation and Membrane Lipid Peroxidation

Drought stress increased ROS production, inducing membrane lipid peroxidation damage in the leaves of wheat seedlings (Figure 4). The O2•– and H2O2 content was markedly increased by 2.8- to 5.2-fold and 1.2- to 1.5-fold in WS1510, respectively, and by 3.8- to 9.2-fold and 1.3- to 2.0-fold in HC1688, respectively, under the P15 and P30 treatments compared with that in the CK (Figure 4A,B). Similarly, the MDA content of P30-treated WS1510 and HC1688 plants was increased by 97.8 and 60.5%, dramatically higher than that in the non-drought-treated plants, respectively (Figure 4C). Compared with the P30-treated plants, the reduction in the O2•– and H2O2 content in the SP30-treated plants was approximately 37.3 and 47.2% in WS1510 and 41.3 and 20.8% in HC1688, respectively (Figure 4A,B). Exogenous uniconazole application significantly reduced the MDA content by 17.2% in WS1510 under the P15 treatment and by 21.3% in WS1510 and 23.4% in HC1688, respectively, under the P30 treatments relative to PEG treatment alone (Figure 4C).

3.4. Antioxidant Enzyme Activity and Osmoregulation Substance

SOD, POD, CAT, and APX activities in the two cultivated varieties were enhanced by the PEG and the combined PEG–uniconazole treatment (Figure 5A–D). Compared with the CK, the PEG treatments sharply increased the SOD, POD, CAT, and APX activities by 1.7- to 7.8-fold, 1.8- to 1.9-fold, 2.2- to 2.8-fold, and 1.1- to 1.3-fold in WS1510, respectively, and 1.8- to 3.9-fold, 1.1- to 1.3-fold, 1.2- to 2.3-fold, and 1.6- to 2.1-fold in HC1688, respectively. SP30 treatment augmented the SOD activity by 24.0% in WS1510 and 34.1% in HC1688, compared with that in the P30-treated plants (Figure 5A). In addition, the POD, CAT, and APX activities of SP30-treated wheat seedlings were markedly increased by 36.2, 32.1, and 33.8% in WS1510, respectively, and by 25.0, 51.9, and 106.6% in HC1688, respectively, relative to that in the P30 treatment alone (Figure 5B–D).
Plants maintain the normal function of cells by producing osmoregulatory compounds such as soluble proteins, proline, and others. Compared with the wheat seedlings grown under normal conditions, PEG treatment increased the soluble protein and proline content of the two wheat varieties (Figure 5E,F). The soluble protein content was increased in the uniconazole-treated plants in combination with the PEG treatment by 0.4–2.8% in WS1510 and 41.1–44.4% in HC1688, respectively, compared to that in PEG-treated plants only, although the differences were not significant in WS1510 (Figure 5E). On the contrary, exogenous uniconazole application prominently reduced the proline content by 47.5–49.5% in WS1510 and 40.3–41.3% in HC1688, respectively, compared to that with PEG treatment alone (Figure 5F).

3.5. Transcriptomic Data Analysis

The cDNA libraries from the RNA extracted from wheat seedling leaves treated with P30 and SP30 were sequenced to elucidate the regulatory mechanisms underlying the uniconazole activity. The GC content of the six libraries ranged from 48.43% to 53.42%, and the Q30 values were over 94.88%. After filtering the raw reads, we generated more than 41,810,186 high-quality clean reads for subsequent analysis (Table 1). More than 93.95% of the reads were mapped to the wheat reference genome (Table S2). Therefore, reliable sequence alignment results were obtained and used for the subsequent bioinformatics analysis.
The number of DEGs between SP30 (uniconazole + 30% PEG) and P30 (30% PEG) was determined and is represented in a volcano plot (Figure S1B), revealing that the number of down-regulated genes was higher than that of the up-regulated genes. There were 3165 DEGs identified among SP30_vs_P30, with 1034 (32.7% of the total) up-regulated DEGs and 2131 (67.3% of the total) down-regulated DEGs, respectively (Figure S1).
The binding (GO:0005488), cell part (GO:0044464), and cellular process (GO:0009987) categories were mainly enriched in the GO enrichment analysis of the DEGs between the SP30 and P30 treatments among the molecular function (MF), cellular component (CC), and biological process (BP) GO categories (Figure S2A). DEGs of the SP30_vs_P30 comparison were enriched in GO terms that were related to the regulation of superoxide dismutase activity (GO:1901668), the positive regulation of superoxide dismutase activity (GO:1901671), magnesium chelatase activity (GO:0016851), the response to gibberellin (GO:0009739), the regulation of the jasmonic acid mediated signaling pathway (GO:2000022), the regulation of oxidoreductase activity (GO:0051341), and others (Figure 6A). Six key DEGs associated with the Mg-protoporphyrin IX chelatase pathway, which is involved in chlorophyll synthesis, were up-regulated in the magnesium chelatase activity (GO:0016851) category in the MF GO classification (Table S4). A total of nine up-regulated DEGs were enriched in the regulation of superoxide dismutase activity (GO:1901668) and positive regulation of superoxide dismutase activity (GO:1901671) categories in the BP GO classification. The enrichment chord diagram of the GO terms indicated that the DEGs significantly enriched in the regulation of superoxide dismutase activity also participated in the positive regulation of superoxide dismutase activity (Figure 6C).
KEGG annotation analysis was used to identify enriched pathways in the SP30_vs_P30 treatment comparison. These included cellular processes, genetic information processing, environmental information processing, organismal systems, and metabolism, which were primarily categorized into carbohydrate metabolism, environmental adaptation, signal transduction, translation and transport, and catabolism pathways (Figure S2B). Among the top 20 metabolic pathways identified by the KEGG enrichment analysis, the MAPK signaling pathway—plant (map04016), plant hormone signal transduction (map04075), and carbon metabolism-related pathways, including starch and sucrose metabolism (map00500), porphyrin and chlorophyll metabolism (map00860), photosynthesis-antenna proteins (map00196), carotenoid biosynthesis (map00906), and carbon fixation in photosynthetic organisms (map00710), were significantly influenced by uniconazole treatment under drought stress (Figure 6B). Specific DEGs in the KEGG pathways had key regulatory roles as shown in Figure 6D.

3.6. Identification of Carbon Metabolism-Related Genes

All 12 DEGs that encoded photosynthesis-antenna proteins (chlorophyll a-b binding proteins, including LHCA2, LHCA3, LHCB1, LHCB3, and LHCB5) were up-regulated in SP30 compared to P30 (Table 2 and Table S3). Among the 24 DEGs enriched in porphyrin and chlorophyll metabolism, 23 DEGs were up-regulated, and 1 DEG was down-regulated in SP30_vs_P30 (Table 2). DEGs such as hemA (2), hemB (1), hemF (2), hemY (3), chlD (3), chlI (3), and por (4) were significantly differentially expressed in SP30_vs_P30. These DEGs participate in the synthesis of chlorophyll a (Figure 7(A1,A2) and Table S4). Among the 12 DEGs enriched in carotenoid biosynthesis, 8 DEGs were up-regulated, and 4 DEGs were down-regulated (Table 2). Phytoene synthase genes (seven), the lycopene epsilon cyclase gene (one), and the beta-carotene hydroxylase gene (one) involved in carotenoid biosynthesis were up-regulated by uniconazole in wheat seedlings under drought stress (Figure 7(B1,B2) and Table S5). In addition, three ABA 8’-hydroxylase genes were down-regulated in the SP30 treatment group in comparison to the P30 treatment group (Table S5).
In total, 17 DEGs (including 12 up-regulated genes and 5 down-regulated genes) enriched in carbon fixation in photosynthetic organisms were identified in the uniconazole-treated wheat seedlings under drought stress (Table 2). Specifically, two ribose 5-phosphate isomerase A genes (rpiAs), four ribulose bisphosphate carboxylase small chain genes (rbcSs), two phosphoglycerate kinase genes (PGKs), and three fructose-bisphosphate aldolase genes (ALDOs) involved in the Calvin–Benson cycle were up-regulated in SP30 compared to P30 (Figure 7(C1,C2) and Table S6). Among the 51 DEGs enriched in starch and sucrose metabolism, 26 DEGs were up-regulated, and 25 DEGs were down-regulated in SP30_vs_P30 (Table 2). Exogenous uniconazole application under drought stress down-regulated four beta-fructofuranosidase genes (INVs) and two sucrose synthase genes (SUSs) involved in the sucrose hydrolysis pathway. In addition, three glucose-1-phosphate adenylyltransferase genes (glgCs), three starch synthase genes (glgAs (2), WAXY (1)), two 1,4-alpha-glucan-branching enzyme 3 genes (GBE1s), three beta-amylase genes (E3.2.1.2s), and one trehalase gene (TREH) involved in sucrose, glucose, starch, and maltose synthesis and hydrolysis were up-regulated in the SP30 treatment group compared to the P30 treatment group (Figure 7(D1,D2) and Table S7).

3.7. Validation of DEGs with qRT-PCR

To validate the DEGs determined by RNA-Seq, the relative expression level of 15 DEGs between the SP30 treatment and P30 treatment involved in carbon metabolism-related pathways were assessed with qRT-PCR. They exhibited highly similar expression to the FPKM measured by RNA-Seq (Figure 8), indicating that the transcriptome data were precise and reliable and could be used to draw reliable conclusions.

4. Discussion

Tissue RWC is considered one of the most easily used agricultural parameters for screening plant drought tolerance. Drought-stress exposure reduced the RWC of wheat plant leaves (Figure 1A), resulting in decreased plant growth and physiological disorders [42]. Drought, one of the major environmental stress factors, restricts plant growth, including plant height, fresh weights, and root length [43]; similar results were found here (Figure 1B–D). Uniconazole negatively affects gibberellin biosynthesis, which regulates cell division and growth during plant growth [15]. Meanwhile, uniconazole has been shown to improve plant drought tolerance by directly improving root growth, reducing leaf growth, and maintaining a higher leaf moisture content, which resulted in greater biomass accumulation [14,44]. Similar results were observed in this study, where exogenous uniconazole application reduced plant height, increased root length and plant fresh weight, and enhanced the leaf RWC of wheat seedlings under drought stress, compared to drought stress alone (Figure 1).
Drought stress increased ROS concentrations that can induce cell membrane lipid peroxidation, and would produce MDA in this process, which is a key indicator for evaluating cell membrane oxidative stress damage [45]. Similar to these findings, a drastic increase in ROS (O2•– and H2O2) and MDA content was observed in wheat seedlings under drought stress (Figure 4), an indication that the cell membranes were severely damaged by stress. It has been demonstrated that improved antioxidant enzymes (SOD, POD, CAT, and APX) activities and protective solute (Pro and soluble protein) accumulation (Figure 5) play an important role in ROS detoxification under environmental stress conditions, can safeguard cell membrane structure stability to maintain normal function [46,47], and are tightly associated with stress resistance, especially drought stress [26,48,49]. The application of exogenous uniconazole enhanced cell membrane stability and reduced membrane damage to improve drought resistance by inhibiting the increase in ROS (O2•– and H2O2) and MDA content in wheat seedlings under drought stress (Figure 4). This could be due to uniconazole decreasing leaf cell membrane peroxidation to sustain regular physiological mechanisms [16] and strengthening antioxidant capacity (Figure 5A–D) to balance ROS generation and elimination [14,50]. Studies have revealed that the induction of SOD gene expression can enhance resistance and adaptability under environmental stress by scavenging excessive ROS [51]. In this study, a total of nine SOD genes were up-regulated by uniconazole under drought stress (Figure 6C). Exogenous uniconazole treatment increased the soluble protein content (Figure 5E), thus regulating leaf senescence [52]. On the contrary, exogenous uniconazole application considerably lowered the proline content in wheat seedlings under drought stress (Figure 5F), similar to a previous study [53,54]. This is further supported by the observation that proline, one of osmoprotectants, is associated with better water status and enhanced photosynthetic ability [55].
Drought stress inhibited photosynthetic pigment synthesis, potentially due to the inhibition of photosynthesis and the damage to the thylakoid membranes [56]. We also concluded that there was a sharp decrease in Chl and Car contents in wheat seedling leaves under drought treatment (Figure 2). Exogenous uniconazole application significantly enhanced plants’ cytokinin biosynthesis, thereby reducing Chl degradation, and promoted Chl biosynthesis [26], improving resistance against drought stress. In agreement with these findings, Chl and Car contents in uniconazole-treated wheat plants under drought stress were significantly higher than those in untreated wheat plants under drought conditions (Figure 2).
Carbon metabolism is the core function of photosynthetic organisms, involving the coordinated operation and regulation of numerous proteins. It is the key metabolic process in plant physiological metabolism and is physically and functionally interconnected with photosynthesis [57]. In order to adapt to environmental changes, plants accumulate water-soluble carbohydrates such as sucrose, fructose, and glucose. Moreover, starch is degraded into soluble sugars [58]. In the present study, we observed an accumulation of sucrose, whereas starch content decreased in wheat seedling leaves under drought stress (Figure 3A,B), similar to findings in Glycine max L. [59]. The mutual conversion of starch and sucrose requires the key enzyme SS for catalysis. Earlier reports indicated that the stress-induced decrease in SS activity [60] might play a role in sucrose decomposition. Similar results were found in our study (Figure 3C), indicating that SS promotes sucrose synthesis and can function as an osmoregulatory compound, an ROS scavenger, and a carbon sink [58]. Studies have shown that uniconazole treatment promoted starch synthesis due to its regulation of key starch synthesis enzymes [24], and the same results were observed in our study (Figure 3B). Specifically, exogenous uniconazole application markedly reduced sucrose content (Figure 3A), due to the acceleration of sucrose conversion to starch, as a result of an increase in SS activity in the starch and sucrose metabolism pathway (Figure 3C).
Photosynthesis provides energy for all life forms as one of the prominent plant biological processes. The first and principal process of photosynthesis is light capture, which is mediated by chlorophyll a-b binding (Lhc) proteins involved in photosynthesis and stress responses [61]. In our study, the chlorophyll a-b binding proteins (LHCA2, LHCA3, LHCB1, LHCB3, and LHCB5) of the photosynthesis-antenna proteins were up-regulated by uniconazole in wheat plants under drought stress (Table S3). These results were consistent with findings on Cannabis sativa L. [25].
Chlorophyll (Chl) biosynthesis is vital for photosynthesis and plant growth and development. Glutamyl-tRNA reductase, the first rate-limiting enzyme of Chl biosynthesis, is involved in Chl biosynthesis by catalyzing glutamate conversion to glutamate-1-semialdehyde [62]. Delta-aminolevulinic acid dehydratase combines two molecules of δ-aminolevulinic acid to form porphobilinogen, which plays a vital role in photosynthesis and respiration [63]. Protoporphyrinogen oxidase, the last key enzyme in the heme and chlorophyll biosynthesis pathways, catalyzes proto-porphyrinogen IX oxidation to proto-porphyrin IX, which is directed towards chlorophyll biosynthesis due to the addition of magnesium [64]. Based on our results, hemA (2), hemB (1), hemF (2), and hemY (3), induced by uniconazole, participate in proto-porphyrin IX biosynthesis from glutamate. Our results showed that uniconazole up-regulated Mg-protoporphyrin IX chelatase and NADPH-protochlorophyllide oxidoreductase (Figure 7A and Table S4), which catalyzes Chl a formation from proto-porphyrin IX, an essential process in Chl biosynthesis [65,66]. This indicates that the increase in Chl content induced by uniconazole in wheat plants under drought stress (Figure 2) can be mainly attributed to the promotion of chlorophyll synthesis rather than chlorophyll degradation inhibition [66].
Carotenoids, located in the chloroplasts, play a crucial role in plant photosynthesis by aiding chlorophyll light energy capture functioning as auxiliary pigments and also protect chlorophyll from damage under environmental stress through the lutein cycle [67]. Phytoene synthase, the key enzyme in the first step of carotenoid biosynthesis, catalyzes the conversion of two geranyl-geranyl-PP molecules into phytoene. The expression of phytoene synthase genes results in changes in the contents of carotenoids [68]. Similarly, uniconazole treatment differentially regulated seven phytoene synthase genes in wheat seedlings under drought stress when comparing the SP30 and P30 treatments (Figure 7B and Table S5). Lycopene epsilon cyclase, a key branch point enzyme, participates in the carotenoid biosynthetic pathway. Some earlier reports indicated that transgenic plants expressing the lycopene epsilon cyclase gene exhibited significantly higher contents of lutein and β-carotene [69], showing high ROS scavenging activity, decreased membrane permeability, enhanced photosynthetic rates, and higher ABA levels [70], resulting in strong stress resistance. β-carotene, a carotenoid compound, plays a critical role in plant light protection and is converted into zeaxanthin by beta-carotene hydroxylase. Transgenic plants overexpressing beta-carotene hydroxylase had higher β-carotene and total carotenoid accumulation, improved radical-scavenging activity, and higher chlorophyll levels and enhanced photosystem II efficiency, exhibiting tolerance to oxidative stress mediated by environmental stress [71]. In the present study, uniconazole up-regulated a lycopene epsilon cyclase gene and a beta-carotene hydroxylase gene in wheat seedlings under drought stress (Figure 7B and Table S5). Carotenoids are precursors of ABA, as endogenous plant hormone that regulates development and stress processes [67]. In addition, uniconazole strongly inhibits ABA 8’-hydroxylase, one of the key enzymes in ABA catabolism, which is involved in many important physiological activities, such as stress resistance and stomatal closure, by controlling ABA concentrations [22]. Our study also found that, compared to untreated plants, uniconazole treatment down-regulated three ABA 8’-hydroxylase genes in carotenoid biosynthesis in wheat plants (Table S5).
Carbon dioxide (CO2) is reduced to produce essential life molecules such as carbohydrates, proteins, lipids, and nucleic acids, which is the main mechanism for energy storage in the biosphere [72]. The principal pathway for CO2 fixation in C3 plants is the Calvin–Benson cycle. Environmental stress can affect carbon fixation by influencing photosynthesis, indirectly impacting photoassimilates’ distribution [73]. Ribose 5-phosphate isomerase A is essential in the Calvin–Benson cycle, playing an important role in carbohydrate synthesis and catabolism [74]. Based on our results, two ribose 5-phosphate isomerase A genes were up-regulated by uniconazole in wheat seedlings under drought stress (Figure 7C and Table S6), which interconverted ribose-5P and ribulose-5P, significant CO2 acceptors in the first dark reaction of photosynthesis [74]. Ribulose-1,5-bisphosphate carboxylase catalyzed the first step in carbon fixation and converted gaseous CO2 (carbon source) into carbohydrates. It has been demonstrated that the carboxylation of ribulose bisphosphate carboxylase is the key factor affecting the metabolic rate of photosynthesis and can improve plant resistance under drought stress [75]. Phosphoglycerate kinase, a soluble enzyme, is essential to the basic metabolism of all organisms and is involved in energy and carbon production for fatty acid synthesis [76]. Some earlier reports suggested that fructose-bisphosphate aldolase is involved in the Calvin–Benson cycle in plastids, participating in sugar metabolism, ABA signal transduction, and plant stress responses [77]. In this study, four ribulose bisphosphate carboxylase small chain genes (rbcS), two phosphoglycerate kinase genes (PGKs), and three fructose-bisphosphate aldolase genes (ALDOs) were identified in uniconazole-treated wheat seedlings under drought stress (Figure 7C and Table S6), indicating that genes of carbon fixation in photosynthetic organisms may be involved in sugar metabolism homeostasis under drought stress, and thus in plant stress tolerance.
Sucrose is transported throughout plant cells and is hydrolyzed into glucose and fructose for various purposes as the main organic carbon source in most higher plants. Sucrose synthase is a key enzyme involved in sucrose metabolic processes, converting sucrose into UDP-glucose, which is involved in the starch biosynthesis pathway [78]. Starch as a carbon source or sink affects carbon distribution. External environmental stress induces starch degradation to enhance the resistance of plants. The principal reason is that starch transforms into soluble sugars that act as osmotic regulatory substances or antioxidant constituents, while stored starch will enable plants to recover quickly when the stress is relieved [78,79]. The results of our study similarly support that drought stress promoted the conversion of starch to sucrose in wheat seedling leaves. At the same time, uniconazole facilitated starch formation (Figure 3A,B), indicating that uniconazole regulated the degree of starch accumulation in plants by modulating the conversion of starch to sucrose. We also found that sucrose synthase genes (SUSs) and beta-fructofuranosidase genes (INVs) were down-regulated in uniconazole-treated wheat seedlings under drought stress (Figure 7D and Table S7). These results are similar to those reported by Li et al. [80], indicating that the expression of SUS and INV accelerates sucrose hydrolysis into glucose and fructose under drought stress. Glucose-1-phosphate adenylyltransferase converts UDP-glucose into ADP-glucose. Starch synthase acts as the key enzyme in starch biosynthesis, catalyzing the α-1,4-glucosidic linkage chain-elongation reaction. Notably, starch synthase gene expression is correlated with starch accumulation in the leaves and grains under drought stress [81]. Based on our results, uniconazole up-regulated glucose-1-phosphate adenylyltransferase genes (glgCs), starch synthase genes (glgAs (2), WAXY (1)), and 1,4-alpha-glucan-branching enzyme 3 genes (GBE1s) (Figure 7D and Table S7), which participate in starch biosynthesis. In addition, beta-amylase genes (E3.2.1.2s) and one trehalase gene (TREH) were up-regulated in the SP30 treatment group compared with the P30 treatment group (Figure 7D and Table S7), which are involved in the process of starch hydrolysis.

5. Conclusions

This study demonstrated that exogenous uniconazole enhanced the drought resistance of wheat. Physiological analysis showed that uniconazole increased the relative water content, improved growth parameters, and maintained cell membrane integrity by regulating superoxide dismutase gene expression, enhancing antioxidant enzyme activities, and adjusting the production of osmoregulatory compounds under drought stress. In addition, uniconazole application suppressed photosynthetic pigment degradation and regulated carbon metabolism-related indicators under drought stress. And transcriptome analysis also found that carbon metabolism-related pathways, such as starch and sucrose metabolism, porphyrin and chlorophyll metabolism, photosynthesis-antenna proteins, carotenoid biosynthesis, and carbon fixation, in photosynthetic organisms were differentially regulated in the uniconazole-treated wheat seedlings. Carbon metabolism-related genes regulated by uniconazole might affect the formation, transformation, and transportation of photosynthetic products in wheat seedlings under drought treatment. In conclusion, exogenous uniconazole can be exploited and applied to maintain the growth and development of wheat plants under drought stress.

Supplementary Materials

The following supporting information can be downloaded at:https://www.mdpi.com/article/10.3390/agronomy14010022/s1, Figure S1: Differentially expressed genes (DEGs) analysis results in SP30_vs_P30. Figure S2: GO (A) and KEGG (B) annotations analysis between SP30_vs_P30. Table S1: Primers used for quantitative real-time PCR (qRT-PCR) in this study. Table S2: The overall analysis of sequence alignment. Table S3: Expression patterns of photosynthesis-antenna-associated genes in uniconazole application (SP30) and control (P30) wheat seedlings under drought stress. Table S4: Expression patterns of porphyrin and chlorophyll metabolism-associated genes in uniconazole application (SP30) and control (P30) wheat seedlings under drought stress. Table S5: Expression patterns of carotenoid biosynthesis-related genes in uniconazole application (SP30) and control (P30) wheat seedlings under drought stress. Table S6: Expression patterns of carbon fixation in photosynthetic organism-associated genes in uniconazole application (SP30) and control (P30) wheat seedlings under drought stress. Table S7: Expression patterns of starch and sucrose metabolism-related genes in uniconazole application (SP30) and control (P30) wheat seedlings under drought stress.

Author Contributions

Conceptualization, methodology, experiment, data curation, visualization, writing—original draft, and funding acquisition, Y.J.; methodology and data curation, H.R.; data curation and visualization, Q.W.; experiment, Y.L., N.L. and W.L.; methodology, M.L.; conceptualization, T.X.; data curation, S.W. and H.Z.; supervision, and writing—review and editing, Y.C.; funding acquisition, supervision, and writing—review and editing, Y.Q. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the Doctoral (Post) Research Initiation Fund Project of Suzhou University (2022BSK036; 2021BSK022; 2021BSK020; 2022BSK024; 2023BSK019; 2021BSK045; 2021BSK019), the Suzhou Science and Technology Plan Project (SZKJXM202208), the Anhui Provincial Key Laboratory Open Fund Funded Project (FECPP202201), and the Key Scientific Research Project of Suzhou University (2021yzd05).

Data Availability Statement

The data presented in this study are available in article.

Conflicts of Interest

The authors declare no conflict of interest.

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Figure 1. Effects of exogenous uniconazole application on relative water content (A), plant height (B), root length (C), and fresh weight (D) of WS1510 and HC1688 under drought stress in wheat seedlings. CK, control (normal water); P15, 15% PEG; P30, 30% PEG; S, uniconazole; SP15, uniconazole + 15% PEG; SP30, uniconazole + 30% PEG. Values are means ± SE (n = 3), and different letters above the columns show a significant difference (p < 0.05) as determined with the Duncan’s test.
Figure 1. Effects of exogenous uniconazole application on relative water content (A), plant height (B), root length (C), and fresh weight (D) of WS1510 and HC1688 under drought stress in wheat seedlings. CK, control (normal water); P15, 15% PEG; P30, 30% PEG; S, uniconazole; SP15, uniconazole + 15% PEG; SP30, uniconazole + 30% PEG. Values are means ± SE (n = 3), and different letters above the columns show a significant difference (p < 0.05) as determined with the Duncan’s test.
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Figure 2. Effects of uniconazole application on Chl a content (A), Chl b content (B), total Chl content (C), and Car content (D) of WS1510 and HC1688 under drought stress in wheat seedlings. Values are means ± SE (n = 3), and different letters above the columns show a significant difference (p < 0.05) as determined with the Duncan’s test.
Figure 2. Effects of uniconazole application on Chl a content (A), Chl b content (B), total Chl content (C), and Car content (D) of WS1510 and HC1688 under drought stress in wheat seedlings. Values are means ± SE (n = 3), and different letters above the columns show a significant difference (p < 0.05) as determined with the Duncan’s test.
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Figure 3. Effects of uniconazole application on sucrose content (A), starch content (B), and SS activity (C) of WS1510 and HC1688 under drought stress in wheat seedlings. Values are means ± SE (n = 3), and different letters above the columns show a significant difference (p < 0.05) as determined with the Duncan’s test.
Figure 3. Effects of uniconazole application on sucrose content (A), starch content (B), and SS activity (C) of WS1510 and HC1688 under drought stress in wheat seedlings. Values are means ± SE (n = 3), and different letters above the columns show a significant difference (p < 0.05) as determined with the Duncan’s test.
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Figure 4. Effects of uniconazole application on O2•– content (A), H2O2 content (B), and MDA content (C) of WS1510 and HC1688 under drought stress in wheat seedlings. Values are means ± SE (n = 3), and different letters above the columns show a significant difference (p < 0.05) as determined with the Duncan’s test.
Figure 4. Effects of uniconazole application on O2•– content (A), H2O2 content (B), and MDA content (C) of WS1510 and HC1688 under drought stress in wheat seedlings. Values are means ± SE (n = 3), and different letters above the columns show a significant difference (p < 0.05) as determined with the Duncan’s test.
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Figure 5. Effects of uniconazole application on SOD activity (A), POD activity (B), CAT activity (C), APX activity (D), soluble protein content (E), and proline content (F) of WS1510 and HC1688 under drought stress in wheat seedlings. Values are means ± SE (n = 3), and different letters above the columns show a significant difference (p < 0.05) as determined with the Duncan’s test.
Figure 5. Effects of uniconazole application on SOD activity (A), POD activity (B), CAT activity (C), APX activity (D), soluble protein content (E), and proline content (F) of WS1510 and HC1688 under drought stress in wheat seedlings. Values are means ± SE (n = 3), and different letters above the columns show a significant difference (p < 0.05) as determined with the Duncan’s test.
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Figure 6. GO and KEGG enrichment analysis of the DEGs among SP30_vs_P30. (A) GO term enrichment analysis of DEGs between the SP30 and P30 treatments. (B) The top 20 metabolic pathways identified by the KEGG enrichment analysis. (C,D) represent the enrichment chord diagram of the 10 significantly enriched GO terms and KEGG pathways, respectively.
Figure 6. GO and KEGG enrichment analysis of the DEGs among SP30_vs_P30. (A) GO term enrichment analysis of DEGs between the SP30 and P30 treatments. (B) The top 20 metabolic pathways identified by the KEGG enrichment analysis. (C,D) represent the enrichment chord diagram of the 10 significantly enriched GO terms and KEGG pathways, respectively.
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Figure 7. Effects of applied exogenous uniconazole application on carbon metabolism-related genes of WS1510 under drought stress in wheat seedlings. (A) Heatmap (A1) and pathway (A2) of selected DEGs involved in porphyrin and chlorophyll metabolism. (B) Heatmap (B1) and pathway (B2) of selected DEGs involved in carotenoid biosynthesis. (C) Heatmap (C1) and pathway (C2) of selected DEGs involved in carbon fixation in photosynthetic organisms. (D) Heatmap (D1) and pathway (D2) of selected DEGs involved in starch and sucrose metabolism. The gene ID of genes listed in (A2), (B2), (C2), and (D2) are shown in Table S4–S7.
Figure 7. Effects of applied exogenous uniconazole application on carbon metabolism-related genes of WS1510 under drought stress in wheat seedlings. (A) Heatmap (A1) and pathway (A2) of selected DEGs involved in porphyrin and chlorophyll metabolism. (B) Heatmap (B1) and pathway (B2) of selected DEGs involved in carotenoid biosynthesis. (C) Heatmap (C1) and pathway (C2) of selected DEGs involved in carbon fixation in photosynthetic organisms. (D) Heatmap (D1) and pathway (D2) of selected DEGs involved in starch and sucrose metabolism. The gene ID of genes listed in (A2), (B2), (C2), and (D2) are shown in Table S4–S7.
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Figure 8. Validation of RNA-seq data of 15 selected genes ((A), TraesCS6B02G175100; (B), TraesCS6D02G136200; (C), TraesCS1B02G191200; (D), TraesCS7A02G125600; (E), TraesCS7B02G382800; (F), TraesCS1B02G186300; (G), TraesCS2D02G563600; (H), TraesCS5D02G365100; (I), TraesCS6A02G271300; (J), TraesCS6B02G298500; (K), TraesCS1D02G313800; (L), TraesCS1A02G313300; (M), TraesCS6D02G403800; (N), TraesCSU02G082000; (O), TraesCS2D02G468900) with quantitative real-time PCR (qRT-PCR).
Figure 8. Validation of RNA-seq data of 15 selected genes ((A), TraesCS6B02G175100; (B), TraesCS6D02G136200; (C), TraesCS1B02G191200; (D), TraesCS7A02G125600; (E), TraesCS7B02G382800; (F), TraesCS1B02G186300; (G), TraesCS2D02G563600; (H), TraesCS5D02G365100; (I), TraesCS6A02G271300; (J), TraesCS6B02G298500; (K), TraesCS1D02G313800; (L), TraesCS1A02G313300; (M), TraesCS6D02G403800; (N), TraesCSU02G082000; (O), TraesCS2D02G468900) with quantitative real-time PCR (qRT-PCR).
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Table 1. Quality control of the sequencing data.
Table 1. Quality control of the sequencing data.
SampleRaw ReadsRaw BasesClean ReadsClean BasesError Rate (%)Q30 (%)GC Content (%)
P30_146,338,7946,997,157,89445,809,2866,827,508,8860.024394.9553.42
P30_252,111,4427,868,827,74251,541,4267,693,136,7830.024195.0648.45
P30_344,987,5266,793,116,42644,583,4026,675,868,5670.023795.5148.43
SP30_149,930,0087,539,431,20849,307,0387,375,979,0770.023895.3949.33
SP30_248,153,4867,271,176,38647,585,0847,111,802,9010.024394.8850.59
SP30_342,245,1166,379,012,51641,810,1866,242,166,3420.024195.0649.82
Table 2. Statistical analysis of KEGG enrichment.
Table 2. Statistical analysis of KEGG enrichment.
DescriptionPathway IDGene NumberUp-Regulated Gene NumberDown-Regulated Gene NumberFirst CategorySecond Category
Starch and sucrose metabolismmap00500512625MetabolismCarbohydrate metabolism
Porphyrin and chlorophyll metabolismmap0086024231MetabolismMetabolism of cofactors and vitamins
Photosynthesis-antenna proteinsmap0019612120MetabolismEnergy metabolism
Carotenoid biosynthesismap009061284MetabolismMetabolism of terpenoids and polyketides
Carbon fixation in photosynthetic organismsmap0071017125MetabolismEnergy metabolism
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Jiang, Y.; Rong, H.; Wang, Q.; Lu, Y.; Li, N.; Li, W.; Li, M.; Xie, T.; Wang, S.; Zhao, H.; et al. Exogenous Uniconazole Application Positively Regulates Carbon Metabolism under Drought Stress in Wheat Seedlings. Agronomy 2024, 14, 22. https://doi.org/10.3390/agronomy14010022

AMA Style

Jiang Y, Rong H, Wang Q, Lu Y, Li N, Li W, Li M, Xie T, Wang S, Zhao H, et al. Exogenous Uniconazole Application Positively Regulates Carbon Metabolism under Drought Stress in Wheat Seedlings. Agronomy. 2024; 14(1):22. https://doi.org/10.3390/agronomy14010022

Chicago/Turabian Style

Jiang, Ying, Hao Rong, Qiang Wang, Yingchao Lu, Na Li, Weiqiang Li, Min Li, Tao Xie, Shanshan Wang, Hong Zhao, and et al. 2024. "Exogenous Uniconazole Application Positively Regulates Carbon Metabolism under Drought Stress in Wheat Seedlings" Agronomy 14, no. 1: 22. https://doi.org/10.3390/agronomy14010022

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