Characterization of a new sg-5 variant with reduced biosynthesis of group A saponins in soybean [Glycine max (L.) Merr.].
Characterization of a new sg-5 variant with reduced biosynthesis of group A saponins in soybean [Glycine max (L.) Merr.].
复制标题
大豆中 A 组皂苷生物合成减少的新 sg-5 变体的表征 [Glycine max (L.) Merr.]。
DOI：
10.1007/s11032-019-1066-4
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发表时间：
2019
影响因子：
3.1
通讯作者：
Jong Tae Song
中科院分区：
文献类型：
--
作者：
Jagadeesh Sundaramoorthy;Sampathkumar Palanisamy;Gyu Tae Park;Hae Reon Son;Chigen Tsukamoto;Jeong-Dong Lee;Jeong Hoe Kim;Hak Soo Seo;Jong Tae Song
三萜皂苷是大豆中主要的次生代谢产物，分为A组皂苷和D组皂苷。A组皂苷引起苦味和涩味，而Daphylococcus皂苷不那么苦，对人体健康更有益。因此，需要进行遗传改良以开发不含皂苷的大豆而不损失其他有益的皂苷。在这项研究中，甲磺酸乙酯（EMS）诱导的突变体，PE 1327，被分离和其特征在于具有降低水平的A组皂苷通过色谱法。PE 1327表型，没有表现出A组皂苷的积累，类似于先前鉴定的Sg-5野生大豆突变体，其生物合成受Sg-5（Glyma.15G243300）基因控制。PE 1327中的Sg-5基因序列揭示了一个单核苷酸多态性（G1036 A），该多态性导致sg-5蛋白的氨基酸从Glu 346变为Lys 346。多种生物细胞色素P450酶的多重比对分析表明，Glu 346在真核生物中高度保守，包括植物和动物，但在原核生物中不保守。预测的Sg-5蛋白的三维模型显示Glu 346残基位于J螺旋上，可能参与了J和K螺旋之间的连接以及J-K环的稳定，这表明在PE 1327突变体中Glu 346被Lys 346取代导致了Sg-5功能的降低。共分离分析表明，Sg-5基因座与PE 1327中A组皂苷生物合成减少紧密连锁，并且新的Sg-5变体对Sg-5是隐性的。
Triterpenoid saponins are major secondary metabolites in soybean; they are classified into group A and DDMP saponins. Group A saponins cause bitterness and an astringent aftertaste, whereas DDMP saponins are less bitter and more beneficial to human health. Therefore, a need exists for genetic improvement to develop bitter-free soybeans without losing other beneficial saponins. In this study, an ethyl methanesulfonate (EMS)–induced mutant, PE1327, was isolated and characterized as having a reduced level of group A saponins by chromatography. The PE1327 phenotype, which exhibits no accumulation of group A saponins, resembles that of a previously reportedsg-5wild soybean mutant whose biosynthesis is controlled by theSg-5(Glyma.15G243300) gene. TheSg-5gene sequence in PE1327 revealed a single-nucleotide polymorphism (G1036A) that causes an amino acid change from Glu346to Lys346in the sg-5 protein. Multiple alignment analysis of cytochrome P450 enzymes from numerous organisms revealed that Glu346is highly conserved in eukaryotes, including plants and animals, but not in prokaryotes. The predicted 3D model of the Sg-5 protein showed that the Glu346residue is located in the J helix and is likely involved in the linkage between the J and K helices and the stabilization of the J-K loop, suggesting that the amino acid substitution from Glu346to Lys346in the PE1327 mutant results in hypofunction of Sg-5. Co-segregation analysis revealed that theSg-5locus is tightly linked to reduced group A saponin biosynthesis in PE1327 and that the novelsg-5variant is recessive toSg-5.