基于转录组学解析苗期高粱对干旱胁迫的生理代谢响应

Physiological and metabolic responses of sorghum seedlings to drought stress revealed by transcriptomic analysis

【目的】研究苗期高粱在不同干旱胁迫时长下的生理代谢及基因表达差异,挖掘高粱抗旱基因,探讨高粱响应干旱胁迫的分子应答机制。【方法】以耐旱高粱品种Tx625B幼苗为试验材料,采用添加25%的PEG-6000模拟干旱胁迫,测定胁迫处理0、12和24 h后叶片生理指标及养分含量;利用转录组测序和生物信息学技术分析叶片的基因表达特征,揭示差异表达基因的生物学功能和主要代谢途径,筛选与抗旱相关的差异表达基因。【结果】不同干旱胁迫时间下,抗旱材料均维持较高过氧化物酶和过氧化氢酶活性和有较强自由基清除能力,有效清除体内过量的活性氧和过氧化氢,降低外界胁迫对植物造成的损伤;干旱胁迫引起了高粱叶片氮、磷、钾含量改变,其中对氮含量的影响较为显著。0 h vs 12 h、0 h vs 24 h、12 h vs 24 h 3个比较组基因比对共检测到17396个干旱响应基因,包括8253个上调基因和9143个下调基因。对共有差异表达基因功能进行分析后,筛选到在高粱苗期抗旱应答中起关键作用的几类基因:过氧化物酶、叶绿素a-b结合蛋白、光系统蛋白、与叶绿体相关的其他酶和蛋白编码基因。差异表达基因GO和KEGG富集分析发现,干旱胁迫对高粱苗期氨基酸代谢、次生代谢产物生物合成、糖类和脂类代谢、植物的信号转导有较大影响,差异表达基因在光合作用、光合生物的暗反应、糖代谢等代谢通路上均有明显富集。【结论】高粱抗旱调节过程涉及多个生物过程的协同互作,通过调节光合作用速率和可溶性糖的积累提高抗旱性;氨基酸代谢途径、光合作用途径和糖代谢途径中差异表达基因的富集是高粱抗旱品种具有较强抗旱调节能力的重要原因。

【Objectives】This study investigated the physiological metabolisms and gene expression patterns of sorghum seedlings under different durations of drought stress,aiming to identify drought-resistant genes in sorghum,and exploring the molecular response mechanisms of sorghum to drought stress.【Methods】Using seedlings of the drought-tolerant variety Tx625B as the experimental material,we simulated drought stress during the seedling stage by applying 25% PEG-6000,measured the physiological indices and nutrient content of the leaves at 0 h,12 h,and 24 h after the treatment.Subsequently,we utilized transcriptome sequencing and bioinformatics techniques to analyze the gene expression profiles of the leaves,aiming to uncover the biological functions and major metabolic pathways of differentially expressed genes(DEGs).This process facilitated the screening of DEGs associated with drought resistance.【Results】Under different durations of drought stress,drought-resistant materials consistently maintain high peroxidase and catalase activities,as well as strong free radical scavenging capabilities.This effectively eliminates excess reactive oxygen species and hydrogen peroxide within the plant,thereby reducing the damage caused by external stress.Drought stress induces changes in the nitrogen,phosphorus,and potassium content of drought-resistant materials,with a more pronounced effect on nitrogen content.A total of 17396 drought responsive genes were detected through sequencing and alignment of three comparison groups:0 h vs 12 h,0 h vs 24 h,and 12 h vs 24 h,including 8253 upregulated genes and 9143downregulated genes.After analyzing the functions of the common differentially expressed genes,we identified several categories of genes that play crucial roles in the drought response during the seedling stage of sorghum:peroxidase,chlorophyll a-b binding proteins,photosystem proteins,and other chloroplast-related enzymes and protein-coding genes.Through enrichment analysis of differentially expressed genes GO and KEGG,it was found that drought stress has a significant impact on amino acid metabolism,secondary metabolite biosynthesis,carbohydrate and lipid metabolism,and plant signal transduction in sorghum seedlings.Differentially expressed genes are significantly enriched in metabolic pathways such as photosynthesis,dark response in photosynthetic organisms,and carbohydrate metabolism.【Conclusions】The drought resistance regulation process of sorghum involves the coordinated interaction of multiple biological processes,which improves drought resistance by regulating photosynthetic rate and soluble sugar accumulation.The enrichment of differentially expressed genes in the amino acid metabolism pathway,photosynthesis pathway,and sugar metabolism pathway is an important reason for the strong drought resistance regulation ability of sorghum drought resistant varieties.