Four mst mutants were detected by Baur (1924); mst in each of them is controlled by single recessive ms genes, the four genes being nonallelic. Two more such mutants, one with and the other without petals, were detected by Goldsmith (1968). Male meiosis and female fertility in these mutants is not known. In one spontaneously arisen and in one other 5-kR γ-ray-induced mst mutant, two nonallelic recessive genes, ms1 and ms2, condition the sterility (this Vol.). Whereas in ms1 tetrads degenerate after formation, in ms2 microspores are liberated but they abort gradually (Table 48.1), so that no viable pollen is produced. The tapetum in both of them develops normally, but it degenerates almost simultaneously with tetrad(ms1) and microspore (ms2) abortion. Thus the ms1 and ms2 genes act upon the tapetum and sporogenous tissue almost simultaneously. Their female fertility is normal. Schick and Stubbe (1932) obtained an induced mst mutant in which the sterility was conditioned by one recessive ms gene, defgli, the gene forming a part of multi-allelic series. The female fertility of this mutant is normal, unlike in its mother mutant parent pet, in which petaloidy of stamens and carpels is most frequent.
KeywordsPollen Development Viable Pollen Female Fertility Male Meiosis Genic Male Sterility
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