EMBRYO CLONING IN PENNISETUM GLAUCUM: PRODUCTION OF MULTIPLE PLANTLETS FROM IMMATURE ZYGOTIC EMBRYOS

摘要

Crop improvement through biotechnological interventions requires efficient in vitro culture systems. Embryos derived from intervarietal as well as interspecific hybridisations have been frequently used for initiating totipotent callus or cell culturesin diverse variety of crop plants Immature embryos are preferred explants for transformation experiments because of their inherent capacity for regeneration and the possibility to isolate several hundred homogeneous explants from single donor plant at the same time They have been widely used in maize, wheat and sorghum (Becker et al., 1994; Casas et al., 1993; Zimny et al., 1995) However, majority of the earlier reports of piant regeneration using immature embryos utilized an intermediate callus phaseFormation of caiius from zygotic embryos (including interspecific hybrids) with regeneration via somatic embryogenesis has been reported in diverse plant species (Williams and Maheswaran, 1986; Sharma et al., 1996), however, the reports on micropropagation of embryos in Pennisetum species are meagre. The available reports involved plant regeneration through somatic embryogenesis following an intervening caiius phase (Vasi! and Vasii, 1981; Botti and Vasil, 1983; Lambe et al., 1999, Oldach et al., 2001)For clona! multiplication, intervening callus phase may not be desirable as there is a likelihood of generation of off type plants through somaclonal mutations (Duncun, 1997; Mohan Jain, 2001), and thus, direct plant regeneration from explants is a preferred approach. In addition to organogenesis and somatic embryogenesis, a third mode for propagation is through multiple shoot formation without an intervening callus phase, referred to as 'embryo cloning' (Williams et al., 1987) Reports on embryo cloningthrough direct multiple shoot formation are limited. The available reports include that of zygotic embryos from Thfolium species (Maheswaran and Williams, 1986), almonds {Hisajima, 1982) and orchard grass (Batygina and Vasiiyeva, 1983). This communication present, a report on generation of multiple plantlets through embryo cloning from the immature zygotic embryos of pearl millet (Pennisetum glaucum).