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采用盆栽试验模拟干旱胁迫(土壤相对含水量40%–45%)在小麦(Triticum aestivum)拔节孕穗期胁迫12天,测定其生长速率、光合特征及关键代谢产物含量,以探讨干旱胁迫对拔节孕穗期小麦叶片初生及次生代谢产物的影响及其涉及的代谢途径,讨论小麦生长代谢变化规律及应答机制。研究表明:干旱胁迫使小麦叶片气孔受限制导致光合速率下降;使叶绿素含量下降直接影响光系统II活性,最终导致生长率降低。检测出的初级代谢产物组包括有机酸、氨基酸、碳水化合物、嘧啶和嘌呤等64个代谢产物,其中29个代谢产物在干旱胁迫下发生明显的变化。主成分分析(PCA)结果显示全部样本均分布在95%的置信区间内,两个主成分得分为64%。单因素方差分析结果表明,干旱胁迫导致苹果酸、柠檬酸、乌头酸等参与三羧酸(TCA)循环的代谢产物消耗明显,且引起大部分氨基酸(如脯氨酸、丝氨酸、缬氨酸)和碳水化合物(肌醇、果糖、葡萄糖)大量积累的同时转氨基代谢(天冬酰胺、谷氨酰胺和γ氨基丁酸)产物消耗,研究证明干旱胁迫明显地促进小麦叶片的糖酵解和氨基酸合成途径,但抑制了TCA循环和转氨基反应,加速氨基酸代谢网络向脯氨酸合成转变过程。这些结果表明干旱胁迫引起了转氨基反应、TCA循环、糖酵解/糖异生、谷氨酸介导的脯氨酸合成,以及嘧啶和嘌呤等代谢网络系统广泛的变化,说明小麦在合成大量的氨基酸和碳水化合物类物质的同时也消耗了大量的能量,暗示了糖异生到脯氨酸合成的转变。
The pot experiment was conducted to simulate the drought stress (relative soil water content 40% -45%) in wheat (Triticum aestivum) for 12 days at the booting stage. The growth rate, photosynthetic characteristics and the contents of the key metabolites were measured to investigate the effect of drought stress on the booting booting The effects of primary and secondary metabolites of wheat leaves and the metabolic pathways involved in wheat leaf metabolism were discussed in order to discuss the regularity and mechanisms of wheat growth and metabolism. The results showed that: under drought stress, the stomatal limitation of wheat leaves led to the decrease of photosynthetic rate; decreasing the content of chlorophyll directly affected the activity of photosystem II, finally leading to the decrease of growth rate. The primary metabolites detected included 64 metabolites such as organic acids, amino acids, carbohydrates, pyrimidines and purines. Among them, 29 metabolites underwent obvious changes under drought stress. Principal component analysis (PCA) results show that all samples are distributed within a 95% confidence interval, with 64% of the two principal components. The results of one-way ANOVA showed that the drought-induced metabolites such as malic acid, citric acid and aconitic acid, which involved in the TCA cycle, were consumed obviously and caused most of the amino acids (such as proline, serine and valine ) And carbohydrate (inositol, fructose, glucose) while transaminase (asparagine, glutamine and gamma aminobutyric acid) product consumption, studies have shown that drought stress significantly promote the wheat leaf glycolysis and Amino acid synthesis pathway, but inhibited the TCA cycle and transamination, accelerate the process of amino acid metabolism to proline synthesis. These results indicate that drought stress induces transamination reactions, TCA cycle, glycolysis / gluconeogenesis, glutamate-mediated proline synthesis, and extensive changes in metabolic network systems such as pyrimidine and purine, Amino acids and carbohydrates also consume large amounts of energy, suggesting a shift from gluconeogenesis to proline synthesis.