Induced polyploidy in Gossypium: A tool to overcome interspecific incompatibility of cultivated tetraploid and diploid cottons

摘要

Asiatic (G. arboreum L.) varieties of cotton have built-in desirable genes for drought tolerance and resistance to insect pests like bollworms, aphids and diseases like black arm, root rot and reddening of leaves, hence they are suitable for dry land conditions and low input technology. On the contrary, American (G. hirsutum) varieties are high yielding and widely grown. However, they lack important characteristics prevalent in diploid cultivated varieties of cotton and their cost of production is therefore relatively high. It is worthwhile to combine the genes for the above-referred desirable characters between G. hirsutum and G. arboreum cotton. However, by conventional breeding methods, the crosses between these two species of cotton are unsuccessful due to abortion of embryo after fertilization because of differences in chromosome numbers of G. arboreum and G. herbaceum (2n = 26) and G. hirsutum (2n = 52). Hence embryo culture method to overcome such situations in production of interspecJfic hybrids was attempted.