Genetics and cytology of a genic male-sterile, female-sterile mutant from a transposon-containing soybean population

A male-sterile, female-sterile soybean mutant (w4-m sterile) was identified among progeny of germinal revertants of a gene-tagging study, Our objectiv es were to determine the genetics (inheritance, allelism, and linkage) and the cytology (microsporogenesis and microgametogenesis) of the w4-m sterile , The mutant was inherited as a single recessive nuclear gene and was nonal lelic to known male-sterile, female-sterile mutants st2 st2, st3 st3, st4 s t4, st5 st5, and st6 st6 st7 st7, No linkage was detected between the w4-m sterile and the w4w4, y10 y10, y11 y11, y20 y20 fr1 fr1, and fr2 fr2 mutant s. Homologous chromosome pairing was complete in fertile plants. Chromosome pairing, as observed in squash preparation, was almost completely absent i n sterile plants. Developmentally microsporogenesis proceeded normally in b oth the fertile and the w4-m sterile through the early microspore stage. Th en the tapetal cells of the w4-m sterile surrounding the young microspores developed different-size vacuoles, These tapetal cells became smaller in si ze and separated from each other. Some of the microspores of the w4-m steri le also became more vacuolate prematurely and sometimes they collapsed, usu ally by the late microspore stage, In the w4-m sterile the microspore walls remained thinner and structurally different from the microspore walls of f ertile plants. No pollen was formed in the mutant plants, even though some of the male cells reached the pollen stage, although without normal filling . The w4-m sterile was designated st8st8 and assigned Soybean Genetic Type Collection number T352.