Abstract: Elymus excelsus Turcz. is a perennial herbaceous plant of the genus Elymus of the Poaceae family. It exhibits traits of vigorous growth,broad foliage,high nutritional value,and favorable palatability,rendering it a superior quality pasture species. In order to explore the drought tolerance of Elymus excelsus,this study used drought resist and drought sensitive Elymus excelsus previously screened from 8 wild resources in Northeast China as test materials,and used 20% PEG-6000 to simulate drought stress. Seedlings (5 weeks old) were treated for 0 (control),3,7 and 14 days. Phenotypes changes were observed,changes in physiological indicators were measured,such as osmotic regulatory substances,reactive oxygen metabolism and antioxidant enzyme activity. And transcriptome sequencing was performed to explore the physiological response and internal regulatory mechanism of Elymus excelsus under drought stress. The results showed that,under drought stress,the drought-tolerant Elymus excelsus exhibited significantly increased contents of proline (Pro),superoxide dismutase (SOD),catalase (CAT),and soluble sugar (SS) compared to the drought-sensitive type (P <0.05). Increased,among which the proline content and soluble sugar content reached the highest on the 14th day of stress,increasing by 20.39% and 19.11% respectively compared with the drought sensitive type. Transcriptome analysis showed that there were 3 463 and 2 651 differentially expressed genes of drought resist and drought sensitive response genes respectively,of which 795 were co-regulated genes,633 were up-regulated and 159 were down-regulated. Drought-tolerant differentially expressed genes are mainly concentrated in pathways such as antioxidant activity,transferase activity,and arginine and proline metabolism. Among them,proB,rocF,and ALDH genes may be involved in the process of Elymus excelsus resisting drought stress. The research results provide a theoretical basis for further exploration of candidate genes and drought resist breeding of Elymus excelsus.

Key words: Drought stress, Elymus excelsus, Transcriptome sequencing, Physiological response, Differentially expressed gene

摘要： 肥披碱草(Elymus excelsus Turcz.)是禾本科披碱草属多年生草本植物，具有生长茂盛、叶片宽厚、营养价值高和适口性好等特点，是一种优质牧草。为探讨肥披碱草的耐旱性，本研究以前期从东北8个野生资源中筛选的耐旱型和干旱敏感型肥披碱草为试验材料，采用20%PEG-6000模拟干旱胁迫对幼苗(5周龄)处理0(对照)，3，7和14 d，观察植株表型、测定渗透调节物质、活性氧代谢和抗氧化酶活性等生理指标的变化，并进行转录组测序，以探究肥披碱草在干旱胁迫下的生理响应及内在调控机制。结果表明：干旱胁迫下，与干旱敏感型相比，耐旱型肥披碱草的脯氨酸(Pro)、超氧化物歧化酶(SOD)和过氧化氢酶(CAT)、可溶性糖(SS)含量均显著升高(P<0.05)，其中在胁迫14 d时脯氨酸含量和可溶性糖含量达到最高，比干旱敏感型分别提高20.39%和19.11%。转录组分析表明，耐旱型和干旱敏感型差异表达基因分别为3463个和2651个，其中有795个共同调控基因，上调633个，下调159个。耐旱差异表达基因主要富集在抗氧化活性、转移酶活性、精氨酸和脯氨酸代谢等途径中，其中proB、rocF和ALDH基因可能参与肥披碱草抵御干旱胁迫过程。本研究为进一步挖掘肥披碱草响应干旱胁迫的候选基因和耐旱育种提供了理论基础。

关键词: 干旱胁迫, 肥披碱草, 转录组测序, 生理响应, 差异表达基因