Analysis of variation in tissue culture response and identification of indica rice genotypes for transformation

Abstract

Genetic variation for in vitro response of 22 elite indica rice cultivars along with Taipei-309, a japonica model variety for tissue culture studies, was investigated. Sequential growth stages of in vitro seed culture for example (i) callus induction and regeneration (ii) calli with green regions (iii) calli with only shoots (iv) calli with both roots and shoots (v) calli with roots only and (vi) plants per unit culture, were measured and analyzed by Duncan's multiple range test. The varieties were clustered into groups by taking into account all the in vitro growth stage parameters. Clustering of indica varieties by three methods viz., canonical analysis, joint score method and non hierarchical euclidean cluster analysis resulted in identification of 2,3 and 4 varieties respectively, in the same genetic cluster with Taipei-309. The analysis based on mean and standard deviation of joint scores for all the traits was shown to be superior to other two methods. Regeneration rather than callus induction was the limiting parameter in most of the varieties. The number of plants regenerated per unit culture and percent calli giving shoots was critical for any genotype before taking up transformation. The indica varieties Vibhava and Seshu were identified as close to Taipei-309 through genetic clustering and therefore should prove to be very suitable for transformation studies.