外源褪黑素对干旱胁迫下高粱生理代谢的调节效应研究

Study on the regulatory effect of exogenous melatonin on the physiological metabolism of sorghum under drought stress

[目的]高粱通常生长于干旱环境,芽苗期时常发生干旱。通过探索外源褪黑素对干旱胁迫下高粱种子芽苗发芽率与生理代谢的影响,解析高粱抗旱调节的生理调节途径和关键路径,可为解决高粱芽苗期种子抗旱萌发受阻、形态建成困难的生产难题提供思路和技术支撑。[方法]以高粱品种‘辽糯11’为试验材料,通过15%PEG模拟干旱胁迫条件,分别设置0、60、120、180、240和300μmol·L^(–1)浓度的褪黑素浸种(对应的简称分别为T-0、T-60、T-120、T-180、T-240和T-300),探究干旱胁迫下外源褪黑素对高粱种子萌发的影响,选取发芽率最高的浓度与对照组T-0进行代谢组学分析。[结果]干旱胁迫下,施用褪黑素提高了高粱种子发芽率。其中T-180高粱种子发芽率最高为75.3%,显著高于其它处理,比T-0增加了77.18%,为褪黑素最佳施用浓度。选取T-180和T-0进行代谢组学分析,2个处理共富集到15条关键代谢途径,分别为嘌呤代谢、色氨酸代谢、嘧啶代谢、氮代谢、精氨酸生物合成、二苯乙烯-二芳基庚烷和姜辣素的生物合成、丙氨酸-天门冬氨酸-谷氨酸代谢、谷胱甘肽代谢、玉米素生物合成、氨酰生物合成、乙醛酸盐和二羧酸盐代谢、异喹啉生物碱的生物合成、氨基酸的生物合成、ABC转运蛋白(ATP-binding cas⁃sette transporter,ABC transporter)和次生代谢产物的生物合成。[结论]综合分析发现,T-180为褪黑素最佳施用浓度,对高粱芽苗施用外源褪黑素后,15条关键代谢途径中嘌呤代谢、色氨酸代谢2个代谢途径变化活跃,是参与抗旱调节的关键代谢途径。

[Objective]Sorghum typically grows in arid environment and often experiences drought during the seedling stage.By exploring the effects of exogenous melatonin on the germination rate and physiological metabolism of sorghum seedlings under drought stress,this study aimed to analyze the physiological regulatory pathways and key mechanisms of drought resistance in sorghum.This can provide insights and technical support for addressing the challenges of drought-impeded seed germination and morphological development during the sorghum seedling stage.[Method]The sorghum cultivar'Liaonuo 11'was used as the experimental material,and the drought stress conditions were simulated using 15%PEG.Seeds were soaked in melatonin solutions at concentrations of 0,60,120,180,240 and 300μmol·L^(–1)(abbreviated as T-0,T-60,T-120,T-180,T-240,and T-300,respectively)to investigate the effects of exogenous melatonin on sorghum seed germination under drought stress.The concentration with the highest germination rate was selected for metabolomic analysis along with the control group T-0.[Result]Under drought stress,the application of melatonin increased the germination rate of sorghum seeds.The highest germination rate was observed in the T-180 group,at 75.3%,significantly higher than other treatments and 77.18%higher than the T-0 group,making it the best melatonin application concentration.Metabolomic analysis of T-180 and T-0 identified 15 key metabolic pathways,including purine metabolism,tryptophan metabolism,pyrimidine metabolism,nitrogen metabolism,arginine biosynthesis,stilbene diarylheptane,and gingerol biosynthesis,alanine,aspartic acid and glutamic acid metabolism,glutathione metabolism,zeatin biosynthesis,aminoacyl biosynthesis,glyoxylate and dicarboxylate metabolism,isoquinoline alkaloid biosynthesis,amino acid biosynthesis,biosynthesis of ABC transporters,and secondary metabolite biosynthesis.[Conclusion]Comprehensive analysis showed that T-180 was the optimal melatonin application concentration.After applying exogenous melatonin to sorghum seedlings,purine metabolism and tryptophan metabolism were the most active among the 15 key metabolic pathways,including their key role in drought resistance regulation.