Genetic Analysis ofcallusinitiation inGossypium tomentosumandGossypium darwinii

Wild cotton species can contribute a valuable gene pool for the genetic improvement of cultivated tetraploid cultivars. But the obstacle is the reproductive isolation of different species. Somatic embryogenesis offers a temporary status for genetic manipulation such as somatic hybridization. The present studies aimed at optimizing the conditions for regeneration of wild species of cotton. Callus were successfully induced from hypocotyls ofGossypium tomentosum(C1genome) andGossypium darwinii(D5genome) on MSB5(MS salts and B5vitamins) medium supplemented with 0.01mg/L 2, 4-D (2, 4-dichlorophenoxyacetic acid), 0.01mg/L KT (kinetin), 0.01mg/L IAA (3-indoleacetlc acid) and 0.60mg/L 2, 4-D, 0.25mg/L KT, respectively. Plant growth regulators (PGRs) combinations, adding high inorganic salt stress, and carbohydrate were used to induce embryogenic callus from nonembryogenic callus. Embryogenic cultures were induced from the two cotton species. Based on studying the effect of PGRs, nitrogen sources, molysite, CuSO4and pH value on somatic embryogenesis (SE), we obtained somatic embryogenesis in theG. tomentosumon the medium with 0.1 mg/L 2, 4-D, 0.1 mg/L KT while deprivation of KNO3. The result gives out new exploration on somatic embryogenesis in cotton to create new germplasm sources.

Collinearity Analysis of Allotetraploid Gossypium Tomentosum and Gossypium Darwinii

G. tomentosum and G. darwinii are wild allotetraploid cotton species, characterized with many excellent traits including finer fiber fineness, drought tolerance, Fusarium wilt and Verticillium wilt resistance. Based on construction of F2 linkage groups of G. hirsutum ?? G. tomentosum and G. hirsutum × G. darwinii, two genetic linkage maps were compared. As a result we found a total of 7 inversion fragments on chr02, chr05, chr08, chr12, chr14, chr16 and chr25, 3 translocation fragments on chr05, chr14 and chr26. Further comparing the inversion and translocation fragments, we noticed four of seven markers orientation of G. tomentosum consistent with G. hirsutum or G. raimondii, one of seven inversion markers orientation of G. darwinii consistent with G. hirsutum；meanwhile one of three translocation marker orientation of G. tomentosum consistent with G. raimondii. The result indicate，compare G. darwinii, G. tomentosum has closer genetic relationship to G. hirsutum. This study will play an important role in understanding the genome structure of G. tomentosum and G. darwinii, and open the doors for further in-depth genome research such as fine mapping, tagging genes of interest from wild relatives and evolutionary study.