Studies on the abnormality of embryo sac and pollen fertility in aurotetraploid rice during different growing seasons

Auto tetraploid rice has a great genetic potential but low seed setting rate is the major encumbrance in its use. Embryo sac fertility and pollen fertility are the most important factors which affect the seed setting rate in auto tetraploid rice. Whole mount eosin B-staining confocal laser scanning microscopy (WE-CLSM) was used to study the fertility and abnormalities in embryo sacs of diploid and auto tetraploid rice during different seasons. The results indicated that the embryo sac fertility (64.5%) was much low in auto tetraploid than that in diploid rice (86%), and five main types of abnormal embryo sac were found in all 10 auto tetraploid rice. Moreover, some other type abnormal embryo sacs were also observed in auto tetraploid rice. Embryo sac without female germ unit and embryo sac degeneration were the most frequent types of abnormalities in auto tetraploid rice. Embryo sac fertility ranged from 49.3% to 79.3%, pollen fertility ranged from 56.2 to 85.9%, and seed setting rate varied from 12.5 to 69.01% in various genotypes of auto tetraploid rice. Embryo sac and pollen fertility were found to have a significant correlation with seed setting rate. Seasons have significant effect on pollen and embryo sac fertility in both type of rice. All the auto tetraploid lines exhibited different types of embryo sac abnormalities which indicated that these might be related to different genotypes. (author)