Inheritance of Low‐Phytate Phosphorus in Soybean

Abstract

A reduction in the phytic acid (phytate) content of soybean [ Glycine max (L.) Merr.] seed would improve the bioavailability of P in rations of nonruminant animals containing soybean meal. A soybean mutant with low phytate and increased inorganic P was developed by the USDA‐ARS and Purdue University. The objective of this study was to determine the inheritance of low phytate in a line derived from the mutant. The low‐phytate line was crossed reciprocally to a line with normal phytate. The F 1 seeds from the reciprocal crosses had normal phytate, indicating complete dominance for the wild‐type alleles and no maternal effects. The segregation of 210 F 2 seeds satisfactorily fit a phenotypic ratio of 15:1 normal to low phytate. The F 2 –derived lines satisfactorily fit a ratio of 7:8:1 homogeneous normal phytate to segregating to homogeneous low phytate. The segregation ratios indicated that low phytate was controlled by recessive alleles designated pha1 and pha2 at two independent loci that exhibited duplicate dominant epistasis. Both of the alleles must be homozygous to obtain low‐phytate seed.