科研之友
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摘要
Group A saponins are thought to be the cause of bitter and astringent tastes in processed foods of soybean (Glycine max), and the elimination of group A saponins is an important breeding objective. The group A saponins include two main Aa and Ab types, controlled by codominant alleles at the Sg-1 locus that is one of several key loci responsible for saponin biosynthesis in the subgenus Glycine soja. However, A0 mutant lacking group A saponin is a useful gene resource for soybean quality breeding. Here, eight Chinese wild soybean A0 accessions were sequenced to reveal the mutational mechanisms, and the results showed that these mutants were caused by at least three kinds of mechanisms involving four allelic variants (sg-1 (0-b2) , sg-1 (0-b3) , Sg-1 (b-0) , and Sg-1 (b-01) ). The sg-1 (0-b2) had two nucleotide deletions at positions + 72 and + 73 involving in the 24th and 25th amino acids. The sg-1 (0-b3) contained a stop codon (TGA) at the 254th residue. The Sg-1 (b-0) and Sg-1 (b-01) were two novel A0-type mutants, which likely carried normal structural alleles, and nevertheless did not encode group A saponin due to unknown mutations beyond the normal coding regions. In addition, to reveal the structural features, allelic polymorphism, and mechanisms of the abiogenetic absence of group A (i.e., A0 phenotype), nucleotide sequence analysis was performed for the Sg-1 locus in wild soybean (Glycine soja). The results showed that Sg-1 alleles had a lower conservatism in the coding region; as high as 18 sequences were found in Chinese wild soybeans in addition to the Sg-1 (a) (Aa) and Sg-1 (b) (Ab) alleles. Sg-1 (a) and Sg-1 (b) alleles were characterized by eight synonymous codons and nine amino acid substitutions. Two evolutionarily transitional allelic sequences (Sg-1 (a7) and Sg-1 (b2) ) from Sg-1 (a) toward Sg-1 (b) were detected.
- 出版日期2018-7
- 单位中国农业科学院
