The genetic variation in drought resistance in eighteen perennial ryegrass varieties and the underlying adaptation mechanisms.

BACKGROUND: Drought resistance is a complex characteristic closely related to the severity and duration of stress. Perennial ryegrass (Lolium perenne L.) has no distinct drought tolerance but often encounters drought stress seasonally. Although the response of perennial ryegrass to either extreme or moderate drought stress has been investigated, a comprehensive understanding of perennial ryegrass response to both conditions of drought stress is currently lacking. RESULTS: In this study, we investigated the genetic variation in drought resistance in 18 perennial ryegrass varieties under both extreme and moderate drought conditions. The performance of these varieties exhibited obvious diversity, and the survival of perennial ryegrass under severe stress was not equal to good growth under moderate drought stress. 'Sopin', with superior performance under both stress conditions, was the best-performing variety. Transcriptome, physiological, and molecular analyses revealed that 'Sopin' adapted to drought stress through multiple sophisticated mechanisms. Under stress conditions, starch and sugar metabolic enzymes were highly expressed, while CslA was expressed at low levels in 'Sopin', promoting starch degradation and soluble sugar accumulation. The expression and activity of superoxide dismutase were significantly higher in 'Sopin', while the activity of peroxidase was lower, allowing for 'Sopin' to maintain a better balance between maintaining ROS signal transduction and alleviating oxidative damage. Furthermore, drought stress-related transcriptional and posttranscriptional regulatory mechanisms, including the upregulation of transcription factors, kinases, and E3 ubiquitin ligases, facilitate abscisic acid and stress signal transduction. CONCLUSION: Our study provides insights into the resistance of perennial ryegrass to both extreme and moderate droughts and the underlying mechanisms by which perennial ryegrass adapts to drought conditions.

Transcriptome and functional analyses reveal ERF053 from Medicago falcata as key regulator in drought resistances.

Medicago falcata L. is an important legume forage grass with strong drought resistant, which could be utilized as an important gene pool in molecular breed of forage grass. In this study, M. falcata seedlings were treated with 400 mM mannitol to simulate drought stress, and the morphological and physiological changes were investigated, as well as the transcriptome changes of M. falcata seedlings at different treatment time points (0 h, 2 h, 6 h, 12 h, 24 h, 36 h and 48 h). Transcriptome analyses revealed four modules were closely related with drought response in M. falcata by WGCNA analysis, and four ERF transcription factor genes related with drought stress were identified (MfERF053, MfERF9, MfERF034 and MfRAP2.1). Among them, MfERF053 was highly expressed in roots, and MfERF053 protein showed transcriptional activation activity by transient expression in tobacco leaves. Overexpression of MfERF053 in Arabidopsis improved root growth, number of lateral roots and fresh weight under drought, salt stress and exogenous ABA treatments. Transgenic Arabidopsis over-expressing MfERF053 gene grew significantly better than the wild type under both drought stress and salt stress when grown in soil. Taken together, our strategy with transcriptome combined WGCNA analyses identified key transcription factor genes from M. falcata, and the selected MfERF053 gene was verified to be able to enhance drought and salt resistance when over-expressed in Arabidopsis.