The Lack of Beta‐amylase Activity in Soybean Cultivar Altona sp1 is Associated with a 1.2 kb Deletion in the 5′ Region of Beta‐amylase I Gene

Abstract

ABSTRACTPrevious studies have identified near‐isogenic soybean [Glycine max (L.) Merr.] lines, one containing normal β‐amylase [α‐1,4‐glucan maltohydrolase (EC 3.2.1.2)] activity (Altona Sp 1b) and the other with undetectable β‐amylase activity (Altona sp 1) in seeds. SDS‐PAGE analysis of 50% isopropanol extracted proteins from soybean seeds revealed a prominent 56 kDa protein. This protein, which was absent in Altona sp 1, was identified as β‐amylase by matrix‐assisted‐laser‐desorption‐time‐of‐flight mass spectrometry (MALDI‐TOF‐MS) and immunoblot analysis using antibodies generated against Arabidopsis β‐amylase. Southern blot analysis showed differences in the sizes of the DNA fragments hybridizing to β‐amylase probe between the near‐isogenic soybean lines. A search of the soybean genome database revealed the presence of nine β‐amylase genes in the soybean genome. We have isolated the β‐amylase gene (GmBAM 1) by screening a genomic library of wild‐type soybean and determined its nucleotide sequence. Analysis of the nucleotide sequence of the GmBAM 1 revealed a complete open reading frame that was interrupted by six introns. In contrast, the GmBAM 1 from Altona sp 1 had a 1207 bp deletion near the 5′ region that included the second and third exon regions. Our results suggest that this deletion may be responsible for the lack of β‐amylase activity in soybean cultivar Altona Altona sp 1.