Prefertilization barriers to interspecific hybridization involving Gossypium hirsutum and four diploid wild species

Abstract

Interspecific hybridization among species of cotton has lead to improvement in productivity, earliness, fibre quality and resistance to pests and diseases. However, wide crosses is often limited by the operation of either pre-or/and post-fertilization barriers. An investigation on pollen tube behaviour of four wild species in the pistils of Gossypium hirsutum was taken up. Pollen germination was normal in crosses involving Gossypium triphyllum and Gossypium armourianum and markedly inhibited in the crosses involving Gossypium davidsonii and Gossypium thurberi. Pollen tubes reached the pistils and fertilization was accomplished within 8 h after pollination (HAP) in control cross. Even though delay in pollen tube was a common phenomenon in all the four crosses successful fertilization was observed in crosses involving G. triphyllum and G. armourianum, as they reached the ovary at 24 HAP. In crosses with G. davidsonii and G. thurberi, pollen tubes failed to reach the ovary even at 24 HAP indicating the presence of strong stylar and ovarian incompatibility. Measures to overcome such barriers to interspecific hybridization in the incompatible crosses are discussed.

Gossypium arboreum Accessions Resistant to Rotylenchulus reniformis

“…Transferring resistance from diploid Gossypium species into tetraploid cotton is difficult. Barriers to hybridization between the different species include mechanisms that prevent fertilization or inhibit development of viable seed from successful fertilizations (Brubaker et al, 1999;Mehetre et al, 2003;Mehetre and Aher, 2004;Ganesh Ram et al, 2008). Techniques such as bridging lines (Brubaker et al, 1999;Romano et al, 2009), induced polyploidy (Mehetre et al, 2003), in vitro interspecific fertilization (Liu et al, 1992), protoplast fusion (Sun et al, 2006), and ovule culture Hsu, 1977, 1978;Bajaj, 1984, 1987) have been used to overcome these breeding limitations.…”

Morphological description of a novel synthetic allotetraploid(A1A1G3G3) of Gossypium herbaceum L.and G.nelsonii Fryx. suitable for disease-resistant breeding applications

“…The superior quality of cotton fiber and the disease resistance of wild cotton have been successfully transferred to cultivated cotton [29,30]; However, diploid wild cotton and tetraploid cultivated cotton are biologically isolated. They are often genetically incompatible, forming a barrier to the full utilization of wild diploid cotton varieties [31][32][33]. We have already obtained an interspecific hybrid F 1 of G. herbaceum and G. raimondii.…”

A New Synthetic Allotetraploid (A1A1G2G2) between Gossypium herbaceum and G. australe: Bridging for Simultaneously Transferring Favorable Genes from These Two Diploid Species into Upland Cotton

“…Wild cotton species are a valuable reservoir of agronomically useful genes and genes conferring resistance to pests and diseases [ 32 , 33 ]. However, wild diploid cotton species have not been fully exploited to broaden the existing narrow genetic base through distant crosses with the world’s major cultivated tetraploid cotton due to both pre- and post-fertilization barriers between these species [ 20 , 21 , 34 , 35 ]. In this study, not only did we successfully obtain an interspecific hybrid F 1 and double its chromosome complement with colchicine, but we also alleviated the incompatibility of the new synthetic tetraploid (A 1 A 1 G 2 G 2 ) by grafting, which will lay a solid foundation for the transfer of genes of interest from the two parental diploid species.…”