The Sp1 Locus in Soybean Codes for β‐amylase1

Abstract

One hundred F2 soybean [Glycine max (L.) Merrill] seeds from the cross PI 87525 ✕ ‘Ebony’ and 116 cultivars from Maturity Groups 00 through IV were analyzed using polyacrylamide gel electrophoresis and amylase assays to determine whether Sp1a and Sp1b seed protein bands were the same as the slow and fast amylase variant bands. In the PI 87525 ✕ Ebony cross, the slow and fast amylase variant bands had precisely the same segregation ratios and the same electrophoretic mobilities as the Sp1a and Sp1b protein bands. For 114 out of 116 cultivars tested, exact correspondence was obtained for Sp1a and slow amylase bands, and Sp1b and fast amylase bands. ‘Chestnut’ lacked an amylase band, however, the Sp1a seed protein band was present. ‘Altona’ was a mixture of genotypes that lacked or had the amylase band. The Altona genotype that had the fast amylase band also had the Sp1b band. The Altona genotype that lacked an amylase band also lacked a Sp1 seed protein band. From the data obtained, we believe that the slow and fast amylase bands are the Sp1a and Sp1b seed protein bands.The use of selective α and β‐amylase inhibition and studies of the hydrolysis of amylopectin by the amylase variant support the hypothesis that the Sp1 locus in soybeans codes for β‐amylase.