Pollen exine ornamentation in the F2 generation of an interspecific hybrid of Chorisia (Bombacoideae, Malvaceae) in relation to inheritance pattern

Abstract

Pollen morphology in ten plants of F2 progeny of an interspecific tree hybrid, Chorisia insignis H. B.& K.×C. speciosa St. Hil (Bombacoideae, Malvaceae) has been studied with a view to have an insight in to the effect of hybridization on the pollen morphological features in F2 generation. The study is a sequel to an earlier study on the pollen morphology of Chorisia species and their F1 hybrid, in which case the hybrid pollen uniformly exhibited the apertural features of the male parent and exine features of the female parent. In the F2 progeny the pollen grains display the apertural feature of the male parent in all the plants. However, with regard to exine ornamentation, variability has been observed. Of the ten plants, two plants exhibit the exine features of the male parent showing empty lumina (without bacula), five plants have their pollen exactly like that of the F1 plant (showing prominent columellar heads in the lumina of the apocolpium region) and the remaining three plants showing columellae in lumina of both apocolpium and mesocolpium region being different from the above types. It has been inferred that the variability in the exine pattern in F2 pollen indicates that the pollen exine pattern in hybrids, perhaps, is not unequivocally controlled by sporophytic or gametophytic genomes.