Multiple shoots induction in wild cotton (Gossypium bickii) through organogenesis and the analysis of genetic homogeneity of the regenerated plants

Abstract

Fertile plants were regenerated via organogenesis from cultures of Gossypium bickii Prokhanov cotyledonary nodes devoid of cotyledons. Cotyledonary nodes from 7-day-old seedlings yielded the maximum number of shoots (9.12 shoots per explant) using MSB medium [MS medium (Murashige & Skoog 1962) and B5 (Gamborg et al. 1968) vitamins] supplemented with the combination of 4 mg/L BAP (N6-benzyladinine) and 0.1 mg/L TDZ (thidiazouron), and the subculture was made on a medium containing 2 mg/L BAP. Elongation of multiple shoots was obtained on MSB medium containing 0.05 mg/L GA3 (gibberellic acid). For rooting, a modified half-strength MS medium was utilized. Some regenerants were transferred to a greenhouse, and most of them were morphologically normal and fertile. Histological studies revealed that proliferating buds originated directly from the superficial layers of the explants. Flow cytometric analyses and chromosome counting suggested that the regenerants and their offsprings were diploid. DNA content of regenerants and their offsprings was homogeneous and similar to that of seed-derived plants with unchanged chromosome number (2n = 26). Random amplified polymorphic DNA (RAPD) analysis confirmed the genetic homogeneity of the regenerants and their offsprings with the diploid parent.