GENETIC AND CYTOLOGICAL ANALYSES OF A PARTIAL-FEMALE-STERILE MUTANT (PS-1) IN SOYBEAN (GLYCINE-MAX, LEGUMINOSAE)

Soybean partial-female-sterile mutant 1 (PS-1) was recovered from a ge ne-tagging study. The objectives were to study the inheritance, linkag e, allelism, and certain aspects of the reproductive biology of the PS -1 mutant. For inheritance and linkage tests, PS-1 was crossed to flow er color mutant Harosoy-w(4) and to chlorophyll-deficient mutant CD-1, also recovered from the gene-tagging study. For allelism tests, recip rocal crosses were made with PS-1 and three other partial-sterile muta nts (PS-2, PS-3, and PS-4) recovered from the same gene-tagging study. The PS-1 mutant is inherited in a 3:1 ratio and is a single recessive gene. Linkage results indicated that the gene for partial sterility i n PS-1 is not linked either to the w(4) locus or to the CD-1 locus. Al lelism tests showed that the gene in PS-1 is nonallelic to the gene in PS-2, PS-3, and PS-4. Investigations of developing and mature pollen indicated no differences in morphology, stainability, or fluorescence between normal and partial-sterile genotypes. The PS-1 mutant is compl etely male fertile. Confocal scanning laser microscopy was used to det ermine that early embryo abortion in PS-1 is due indirectly to abnorma l migration of the fused polar nucleus, which prevented it from being fertilized. Subsequent absence of endosperm development leads directly to abortion of the proembryo.