Cytological studies on the influence of male-sterile mutant ms1 on reproductive function in soybean (Glycine max (L.) Merr.)

摘要

Genetic male-sterile and female-fertile ms1 mutants are characterized by (1) formation of coenocytic microspores, due to the failure of cytokinesis after telophase II of meiosis and (2) production of polyembryony, haploidy, and polyploidy in both polyembryonic and monoembryonic progenies;Studies on the frequency of polyembryony and polyploids from the progeny of male-sterile ms1 ms1 plants were conducted among four spontaneous and independent ms1 source populations, designated North Carolina (NCms), Tonica (Tms), Ames (Ams), and Urbana (Ums) male steriles, and two populations derived from F(,4) seeds of crosses of two male-sterile (ms1) lines to two homozygous chromosome-interchange lines (Ames x Clark T/T, and Ums x KS-172-11-3). Results from this study indicate that (1) the character of male-sterility (ms1) is associated with formation of polyembryony and polyploids in all six ms1 source populations; (2) occurrence of polyembryony and polyploidy could be affected by modifier gene(s), different alleles at the ms1 locus, different genetic backgrounds, or by environmental factors;Meiotic studies of triploid plants obtained from the ms1 progeny provide some evidence supporting the hypothesis of duplicated genomes or polyploid origin of soybean. Evidence includes formation of multivalents other than trivalents, non-homologous chromosome associations, secondary chromosome associations, and aberrant nucleolar distribution. Aneuploids with various chromosome numbers were obtained from progeny of triploids;Pollen germination and pollen-tube growth were studied by using light and fluorescence microscopy. Natural pollen-tube growth in sterile anthers was noted in all four spontaneous and independent ms1 source lines. The Ums line tended to have the highest percentage of natural pollen-tube growth in the sterile anthers. Nevertheless, studies on natural self-pollination and artificial cross-pollination in the Ums line indicate that coenocytic pollen grains were not effective in fertilization.