| Popis: |
It was found that, in some of the plants in generations C1-C5 of induced tetraploids in the semisterile sorghum line AS-1-30, more than 30% of pollen grains (PGs) have sizes typical of haploid PGs. Pollen of these plants was used to pollinate different lines of sorghum with cytoplasmic male sterility (CMS). Diploid hybrids were obtained, which confirms the presence of haploid PGs in the tetraploids studied. When tetraploid plants with an increased frequency of haploid PGs were pollinated with pollen of plants from fertile diploid lines, diploid hybrids were also obtained. This demonstrates that the tetraploids studied had haploid ovicells. In generation C4, a chimeric plant was found; one of its shoots was diploid (judging from morphological characters) and produced as many as 99% of haploid PGs. It is assumed that haploid gametes in autotetraploids are formed through somatic reduction of chromosomes at different ontogenetic stages. |
