2006 年 71 巻 4 号 p. 407-418
Present study attempts to explore the possibility of successfully transferring the jassid resistant genes from 2 wild cotton species G. armourianum (Kearney. (2n=2x=26) D2A) and G. raimondii (Ulbrich. (2n=2x=26) D5) into the cultivated G. hirsutum genotypes through backcrossing and colchiploidy. The investigation revealed that viable seeds of the crosses between G. hirsutum and wild diploid species G. armourianum and G. raimondii were obtained using G. hirsutum as female. The backcrosses using the triploid (F1), as female and tetraploid hirsutum as males was not successful, the reciprocal yielded few seeds. Of 432 F1 plants treated with colchicine, only 2 plants each in the crosses viz., Surabhi×G. raimondii and MCU 9×G. armourianum were polyploidised. The colchiploids C1 (Surabhi×G. raimondii) showed larger leaves, flowers, petal size, petal spot, thick leaves, anther density and increased pollen fertility, whereas C1 (MCU 9×G. armourianum) showed stunted growth, hard stem and thick leaves. Leaf hairiness, leaf texture and leaf shape of the BC1 plants [C1 (Surabhi×G. raimondii)×Surabhi] resembled its donor parent. This indicates that the hairiness, which is an important character conferring jassid resistance, has descended from the wild parent G. raimondii. The BC1 plants of C1 (MCU 9×G. armourianum) had leathery leaves and deterring citronella like odour contributing to jassid resistance is derived from the wild species G. armourianum. The result of cytological investigations also supported the crossability behaviour as a close homology between chromosomes of G. armourianum, G. raimondii and G. hirsutum. In the present study, greater homology observed between A and D genomes aids in production of desirable recombinants despite minor cytological disturbances, as there are successful boll setting and viable seed production. Hence, these species with D genome can be used successfully in gene transfer if fertilization barriers are overcome by novel techniques.