A recently evolved BAHD acetyltransferase, responsible for bitter soyasaponin A production, is indispensable for soybean seed germination

作者：Jia Yuan, Liya Ma, Yan Wang, Xindan Xu, Rui Zhang, Chengyuan Wang, Wenxiang Meng, Zhixi Tian, Yihua Zhou, Guodong Wang · 发表于：Journal of Integrative Plant Biology · 年份：2023 · DOI：10.1111/jipb.13553 · 被引用次数：25 · 研究领域：Phytoestrogen effects and research、Microbial Metabolites in Food Biotechnology

Soyasaponins are major small molecules that accumulate in soybean (Glycine max) seeds. Among them, type-A soyasaponins, fully acetylated at the terminal sugar of their C22 sugar chain, are responsible for the bitter taste of soybean-derived foods. However, the molecular basis for the acetylation of type-A soyasaponins remains unclear. Here, we identify and characterize GmSSAcT1, encoding a BADH-type soyasaponin acetyltransferase that catalyzes three or four consecutive acetylations on type-A soyasaponins in vitro and in planta. Phylogenetic analysis and biochemical assays suggest that GmSSAcT1 likely evolved from acyltransferases present in leguminous plants involved in isoflavonoid acylation. Loss-of-function mutants of GmSSAcT1 exhibited impaired seed germination, which attribute to the excessive accumulation of null-acetylated type-A soyasaponins. We conclude that GmSSAcT1 not only functions as a detoxification gene for high accumulation of type-A soyasaponins in soybean seeds but is also a promising target for breeding new soybean varieties with lower bitter soyasaponin content.