Selenocysteine methyltransferase SMT catalyzed the synthesis of Se-methylselenocysteine to regulate the accumulation of glucosinolates and sulforaphane in broccoli  

作　　者：Qi Wu Junwei Wang Yuxiao Tian Chunyan Zhou Shuxiang Mao Qiuyun Wu Ke Huang 

机构地区：[1]College of Horticulture,Hunan Agricultural University,Changsha,Hunan 410128,China [2]Engineering Research Center for Horticultural Crop Germplasm Creation and New Variety Breeding,Ministry of Education,Changsha,Hunan 410128,China [3]Key Laboratory for Vegetable Biology of Hunan Province,Changsha,Hunan 410128,China

出　　处：《Horticultural Plant Journal》2024年第5期1151-1164,共14页园艺学报（英文版）

基　　金：the Projects of International Cooperation National Key R&D Program of China(Grant No.2022YFE0108300);the National Key Research and Development Program of China(Grant No.2022YFF1003000);the National Natural Science Foundation of China(Grant Nos.32372682,32272747,32072585,32072568).

摘　　要：Selenocysteine methyltransferase(SMT)is a key enzyme involved in the Se metabolism pathway,and it is responsible for the catalysis of Se-methylselenocysteine(SeMSC)compound formation.Previous studies showed that selenium treatment activated SMT expression and promoted the accumulation of glucosinolates(GSLs)and sulforaphane,but the roles and functional mechanisms of SMT in mediating GSLs and sulforaphane synthesis remain unclear.In this study,we identified the BoSMT gene in broccoli and uncovered its roles in mediating GSLs biosynthesis.Transgenic assays revealed that BoSMT is involved in SeMSC biosynthesis in broccoli.More importantly,the contents of GSLs and sulforaphane were significantly increased in the BoSMT-overexpressing broccoli lines but decreased in the knockdown lines,suggesting that BoSMT played a positive role in regulating GSLs and sulforaphane synthesis.Further evidence indicated that BoSMT-mediated overaccumulation of GSLs and sulforaphane might be due to the increase in the endogenous SeMSC content.Compared with the mock(water)treatment,selenite-induced significantly increases of the SeMSC content in the BoSMT-knockdown plants partially compensated the phenotype of GSLs and sulforaphane loss.Compared with the mock treatment,exogenous SeMSC treatment significantly increased the contents of GSL and sulforaphane and activated GSL synthesis-related gene expression,suggesting that SeMSC acted as a positive regulator for GSL and sulforaphane production.Our findings provided novel insights into selenium-mediated GSLs and sulforaphane accumulation.The genetic manipulation of BoSMT might be a useful strategy for improving the dietary nutritional values of broccoli.

关 键 词：Selenocysteine methyltransferase Transgenic broccoli Se-methylselenocysteine Glucosinolate sulforaphane Selenium 

分 类 号：S635.3[农业科学—蔬菜学]