新疆大叶苜蓿蔗糖合酶基因家族鉴定及干旱胁迫下表达模式分析OA

Sucrose synthase(SUS)is a key regulatory enzyme in plant sugar metabolism and plays a central role in plant responses to abiotic stresses.This study employed an integrated bioinformatics and transcriptomics approach to systematically identified the SUS gene family(designated as MsSUSs)in Medi-cago sativa'Xinjiang Daye'and elucidated their transcriptional regulatory mechanisms under drought stress.The results showed that the genome of M.sativa'Xinjiang Daye'contains 31 SUS genes distrib-uted across 25 chromosomes,which are classified into three subfamilies:SUS Ⅰ,SUS Ⅱ,and SUS Ⅲ.The MsSUS proteins are predominantly hydrophilic and acidic,with most localized in the cytoplasm.Pro-teins interaction analysis revealed that MsSUSs interact with members of the glycoside hydrolase(GH)fam-ily.Expression analysis revealed that ten MsSUS genes were significantly upregulated under drought stress,among which MsSUS7 and MsSUS24 exhibited the greatest increases,with expression levels under severe water deficit(soil moisture content at 20%-50%of field capacity)reaching 3.74 and 8.34 times that of the control,respectively.The promoter regions of MsSUSs contain abundant abiotic stress-responseve elements,such as ABRE and MBS,as well as numerous binging sites for MADS transcription factors.Among them,15 MsMADS genes were highly expressed under drought stress,with MsMADS33 showing sustained up-regulation following stress treatment.Molecular docking analysis suggested that the MADS-box domain may bind to the promoter regions of MsSUS9 and MsGH5 via hydrogen bonds.In summary,this study predicts that MsSUSs may cooperate regulate sucrose metabolism with MsGHs under drought stress,thereby enhancing osmotic balance and cell wall stability to improve the drought tolerance of M.sativa'Xinjiang Daye',a process potentially positively regulated by MsMADS33.