Pollen germination characteristics, pollen-pistil interaction and reproductive behaviour in interspecific crosses among Abelmoschus esculentus Moench and its wild relatives

摘要

Pollenpistil interactions play a crucial role in successful introgressions for desirable traits and are often restricted by presence of pre- or post-fertilisation barriers in various crops. Importance of wild germplasm of Abelmoschus (Malvaceae) as source of genes for biotic and abiotic stress resistance in crop improvement programmes have long been recognised by breeders. In the present study, behaviour of pollen germination and pollen tube growth were evaluated with respect to the seed set among four species of Abelmoschus. Alien pollen tubes showed significantly high growth inhibition in okra (A. esculentus) pistils and seldom penetrated the stigma. Pollen tube growth was normal in A. esculentusxA. caillei and its reciprocal cross, indicating the potential for its use in genetic improvement. Delayed pollen tube growth along with other structural abnormalities like twisting, swelling, high branching, bi-furcated tip and variation in callose form (reverse orientation and irregularity in callose plugs along the pollen tube) were frequently noticed in the interspecific crosses. The results indicated that the crosses A. manihot subsp. tetraphyllus var. pungensxA. esculentus had high incompatibility, while A. manihot subsp. tetraphyllus var. tetraphyllusxA. esculentus were partially compatible and A. esculentusxA. caillei were fully compatible.