Kim, Won-Seok , Krishnan, Hari B. .
A 1.2 kb deletion in the 5' region of the β-amylase gene is responsible for the reduced β-amylase activity in soybean cultivar Altona sp1.
β-amylase [α-1,4-glucan maltohydrolase (EC 18.104.22.168)] catalyzes the release of β-anomeric maltose from the nonreducing ends of starch. This ubiquitous enzyme is expressed abundantly in soybean seeds. Earlier, two soybean near isogenic lines, one containing normal β-amylase activity (Altona Sp1b) and the other with undetectable β-amylase activity (Altona sp1) have been characterized. In this study, we report the molecular characterization of this β-amylase mutant. Southern blot analysis under stringent hybridization conditions revealed that there are at least two copies of this gene in the soybean genome. Analysis of XbaI and NdeI digested genomic DNA revealed differences in the sizes of the DNA fragments hybridizing to β-amylase probe between the two soybean near isogenic lines. The β-amylase gene from the wild-type and Altona sp1 were PCR amplified from genomic DNA based on the published β-amylase cDNA sequence. Analysis of the nucleotide sequence of the β-amylase gene from the wild-type revealed a complete open reading frame that was interrupted by six introns. In contrast, the β-amylase gene from Altona sp1 had a 1207 bp deletion near the 5’ region that included the second and third exon regions. SDS-PAGE analysis revealed that the β-amylase mutant, in contrast to the wild-type, accumulated trace amounts of a 52 kD protein. Northern blot analysis revealed the accumulation of 1.6 kB RNA transcript in developing seeds of the wild-type but not in Altona sp1. Interestingly, a less abundant truncated RNA transcript was detected in Altona sp1. Our results demonstrate that the deletion in the 5’ region of the β-amylase gene is responsible for the lack of β-amylase activity in soybean Altona sp1 β-amylase mutant.
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1 - USDA-ARS, Plant Genetics Research Unit, 310 Curtis Hall, University of Missouri-Columbia, Columbia, MO, 65211, U.S.A
2 - USDA-ARS, Plant Genetics Research Unit
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM