水分调控对蒙古黄芪毛蕊异黄酮葡萄糖苷生物合成的影响

Effects of water regulation on biosynthesis of calycosin-7-O-β-D-glucoside in Astragalus membranaceus var.mongholicus

以二年生盆栽蒙古黄芪为试验材料,探究水分调控对毛蕊异黄酮葡萄糖苷生物合成的影响,并从其合成途径关键酶基因表达及抗氧化酶系统等角度阐释其机制。采用HPLC测定毛蕊异黄酮葡萄糖苷含量,利用实时荧光定量PCR法分析其合成途径中6个关键酶基因(PAL、4CL、CHS、CHI、IFS、13’H)表达量,同时对保护酶活性、渗透调节物质和丙二醛含量进行测定。结果表明,水分亏缺组毛蕊异黄酮葡萄糖苷,在处理第24天达到最大值0.49 mg·g^(-1);整个调控期间,水分亏缺组渗透调节物质和MDA含量均高于充沛组;水分调控初期黄芪抗氧化酶类SOD、POD、CAT活性升高,但随时间延长其活性下降;水分亏缺组PAL、CHS、13’H基因表达量始终处于较低水平,4CL基因表达活跃,略低于充沛组;CHI、IFS基因在感受到水分亏缺时表达量迅速升高。相关性分析显示,毛蕊异黄酮葡萄糖苷含量与CHI基因表达量呈极显著正相关,与IFS基因表达量呈显著正相关。因此,水分调控可改变毛蕊异黄酮葡萄糖苷的积累模式,水分亏缺方式可能是提高其含量的有效手段。其中CHI、IFS基因为响应水分亏缺毛蕊异黄酮葡萄糖苷积累的关键基因。

The effects of water regulation on the biosynthesis of calycosin-7-O-β-D-glucoside in 2-year-old Astragalus membranaceus var.mongholicus were studied,and the mechanism was explained from the aspects of key enzyme gene expression and antioxidant enzyme system.The content of calycosin-7-O-β-D-glucoside was determined by HPLC,and the expression levels of six key enzyme genes(PAL,4 CL,CHS,CHI,IFS,13’H)in the synthesis pathway were analyzed by q RT-PCR.The activities of protective enzymes and contents of osmoregulation substances and malondialdehyde were also determined.In the water deficit group,the maximum concentration of calycosin-7-O-β-D-glucoside was 0.49 mg·g^(-1) on the 24 th day of treatment.In the whole water regulation,the water deficit group outweighed the water adequate group in osmoregulation substance and MDA contents.The activities of A.membranaceus var.mongholicus antioxidant enzymes SOD,POD,and CAT increased during the initial period of water regulation,but decreased with time.The expression of PAL,CHS,and 13’H in the water deficit group was at a low level,and the 4 CL had active expression,slightly lower than that in the water adequate group.The expression of CHI and IFS elevated rapidly when water deficit occurred.Correlation analysis showed that the content of calycosin-7-O-β-D-glucoside was positively correlated with CHI expression(P<0.01)and IFS expression(P<0.05).Therefore,water regulation can change the accumulation pattern of calycosin-7-O-β-D-glucoside,and water deficit may be an effective way to increase its content.CHI and IFS are the key genes in response to water deficit.