2001 SAKHANOKHO Induction of Highly Embryogenic Calli.pdf

Induction of Highly Embryogenic Calli and Plant Regeneration in Upland (Gossypium hirsutum L.) and Pima (Gossypium barbadense L.) Cottons Hamidou F. Sakhanokho, Allan Zipf,* Kanniah Rajasekaran, Sukumar Saha, and Govind C. Sharma ABSTRACT generation of commercial transgenic cottons, which are obtained by backcrossing a transgenic Coker plant toTo accomplish our objective of broadening the number of regenera- an elite cultivar. Identification of additional regenerableble cotton lines, we developed a protocol capable of producing plants commercial cultivars of cotton would be highly benefi-through somatic embryogenesis of diverse cotton species. Callus was initiated from hypocotyl and cotyledon explants on a callus initiation cial to accelerating the development of transgenic Up- medium [CIM; modified MS with 1 mg L
1 kinetin and 2 mg L
1 land cottons. naphthaleneacetic acid (NAA)]. Friable embryogenic callus was peri- Pima (G. barbadense L.) cottons are becoming popu- odically selected and transferred onto callus selection/maintenance lar in the U.S. cotton market because of their superior medium (CS/MM) [modified MS with 0.1 mg L
1 kinetin and 0.5 mg fiber quality and fineness. There have been some pub- L
1 NAA]. The selected callus was then transferred into a liquid lished attempts at regenerating Pima cotton through embryo initiation medium (EIM) (modified MS medium in which tissue culture, but all the successful reports that we areNH4NO3 was removed and KNO3 amount doubled) followed by trans- currently aware of deal with shoot apex regenerationfer to solid embryo maturation media EMMS2 (0.5 mg L
1 NAA  0.05 (Gould et al., 1991). Application of shoot apex regenera-mg L
1 kinetin). The liquid step not only decreased the culturing time tion is often limited in transformation research becausebut also increased the number of embryos per gram of cultured tissue. it sometimes produces undesirable chimeric tissues.Germinating somatic embryos were placed on MS medium wit