Suja (2002) and Nirmal Babu et al. (2003) used RAPD profiles amplified by 11 operon primers as an index for estimating genetic fidelity of selected "variants" among micropropagated and callus-regenerated plants. They observed differences in RAPD profiles observed in some of the micropropagated plants that indicated micropropagation even without the callus phase induced variations in 9 of the 13 plants tested. Similar differences were noticed among 12 out of 15 callus-regenerated plants. In general, this indicates a high amount of variability among the selected micropropagated and callus-regenerated plants of ginger, and the majority of the morphological variants selected from earlier studies did show variations in RAPD profiles (see Figure 4.4b and c). Earlier studies by Rout et al. (1998) indicate that RAPD profiles did not indicate any polymorphism among the micropropagated plants. The observations of Suja (2002) and Nirmal Babu et al. (2003) differ with the earlier finding. The variability observed may be due to bigger population size used by the latter workers to detect the morphological variants first and confirmation of their genetic nature of variation using RAPD profiles subsequently. Other workers also reported somaclonal variation in ginger (Kulkarni et al., 1987; Samsudeen, 1996; Nirmal Babu, 1997), probably because of the genetic nature of ginger that has resulted in many varieties and cultivars even without sexual reproduction. However, the microrhizome-derived plants did show a high degree of genetic uniformity as expressed by RAPD profiles (see Figure 4.4d). Thus, the present study indicated that direct micropropagation of ginger results in somclonal variation; hence, propagation of ginger through microrhizome pathway significantly reduces this variation.
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