Expression of the apomictic potential and selection for apomixis in sorghum line AS-1a

Expression of elements of apomixis was studied for ten seasons in sorghum line AS-1a and its backcross hybrids in the 9E and A3 sterile cytoplasms. Cytoembryological analysis revealed aposporous embryo sacks (apo-ESs), their initial cells, and, rare, parthenogeneic proembryos in ovules of line AS-1a and its BC 2 and BC 3 hybrids on the 9E cytoplasm. The A3 sterile cytoplasm suppressed the development of parthenogenetic proembryos, but did not affect the apo-ES formation. The frequency of apomictic elements increased in seasons with high daily temperatures and total precipitation deficiency in the period of ovule and megagametophyte development ( r = −0.805, p