Production and Fertility Restoration of an Interspecific Hybrid between Gossypium hirsutum L. and G. raimondii U.

Interspecific hybrids between 2 cultivated varieties (MCU 5 and MCU 7) of tetraploid cotton (Gossypium hirsutum) and diploid perennial species G. raimondii were synthesized. The resulting triploid F1s were pollen sterile and exhibited irregular meiosis with frequent formation of univalents and multivalents. Mean chromosome association of the triploid hybrids were 11.50 I+9.97 II+2.31 III+0.16 IV and 0.50 I+11.35 II+0.96 I. Successful synthesis of hexaploids involoving G. raimondii by doubling the genomes of the triploid hybrids with 0.1% colchicine and enhancement of fertility status in hybrids is reported for the first time. The mean chromosomal association of hexaploid hybrids were 4.05 I+26.91 II+4.45 III+1.23 IV+0.32 V and 1.26 I+25.81 II+1.18 III+5.19 IV respectively. The heterozygosity of triploid and hexaploid hybrids was also confirmed through SSR marker analysis. Further utility of the developed hybrids with respect to jassid resistance breeding in cotton is discussed.