EFFECT OF IN VITRO CULTURE CONDITIONS ON SOMACLONAL VARIATION IN COWPEA (VIGNA UNGUICULATA WALP.) USING RAPD MARKERS

We report a high frequency regeneration protocol in cowpea (Vigna unguiculata Walp. var. C 152) via somatic embryogenesis from 10-d-old primary leaf explants. A study was conducted to examine the effect of somaclonal variations in in vitro derived cowpea plants under field conditions. The regenerated plant-lets were successfully transferred to field after hardening in vitro and grown for collecting R-0, R-1 and R-2 seeds. The seeds of R-1 and R-2 generations were subsequently, grown under field conditions and their various biometrical traits were compared and evaluated with non-tissue cultured cowpea plants as check. There was no detectable somaclonal variation induced in R-0-R-2 in any of the biometrical traits. The results indicate that the inclusion of different plant growth promoters at specified concentrations and duration in our earlier tissue culture work did not induce any detectable mutation. The RAPD analysis also shows that there is no genetic variation among R-2 cowpea plants. The somatic embryogenesis protocol we report could thus be safely applied for high frequency true-to-type regeneration and transformations protocols without any somaclonal variation.