With the ever-changing environment and climate, high salinity has become a major environmental issue that threatens crop quality and yield. Alfalfa (Medicago sativa L.) is a perennial forage crop planted worldwide that has a well-developed root system and salt tolerance. Cytochrome P450 monooxygenase (CYP450) genes play important roles in flavonoid synthesis, plant growth, and development. However, few studies have focused on CYP450s in forage grass, especially the role of CYP450 genes in plant resistance to environmental stresses, such as drought and high salinity. In this study, 376 menbers in MsCYP family genes were identified using hmmsearch and BLASTP in the alfalfa protein database using the AtCYP450 protein sequence. Then by exploring MsCYP gene structures, tandem and segmental duplication events, and evolutionary relationships with CYP450s in other plants, potential MsCYPs that respond to salt stress were screened. Candidate genes were selected for transient expression in tobacco and heterologous overexpression in Arabidopsis for salinity response. This study provides a foundation for verifying the function of MsCYPs in improving the quality of agricultural products.

BackgroundDrought is one of the main abiotic factors that affect alfalfa yield. The identification of genes that control this complex trait can provide important insights for alfalfa breeding. However, little is known about how alfalfa responds and adapts to drought stress, particularly in cultivars of differing drought tolerance. ResultsIn this study, the drought-tolerant cultivar Dryland ‘DT’ and the drought-sensitive cultivar WL343HQ ‘DS’ were used to characterize leaf and root physiological responses and transcriptional changes in response to water deficit. Under drought stress, Dryland roots (DTR) showed more differentially expressed genes than WL343HQ roots (DSR), whereas WL343HQ leaves (DSL) showed more differentially expressed genes than Dryland leaves (DTL). Many of these genes were involved in stress-related pathways, carbohydrate metabolism, and lignin and wax biosynthesis, which may have improved the drought tolerance of alfalfa. We also observed that several genes related to ABA metabolism, root elongation, peroxidase activity, cell membrane stability, ubiquitination, and genetic processing responded to drought stress in alfalfa. We highlighted several candidate genes, including sucrose synthase, xylan 1,4-beta-xylosidase, primary-amine oxidase, and alcohol-forming fatty acyl-CoA reductase, for future studies on drought stress resistance in alfalfa and other plant species. ConclusionsIn summary, our results reveal the unique drought adaptation and resistance characteristics of two alfalfa genotypes. These findings, which may be valuable for drought resistance breeding, warrant further gene functional analysis to augment currently available information and to clarify the drought stress regulatory mechanisms of alfalfa and other plants.