NaCl impact on somaclonal variation exhibited by tissue culture-derived fertile plants of rice (Oryza sativa L.)

In order to analyse the effects of NaCl added to in vitro culture media on subsequent somaclonal variation exhibited by regenerated plants (R-0) and their R-1 and R-2 progenies, four procedures of in vitro selection differing in the stage of stress imposition were applied to mature embryo-derived calli obtained from three rice cultivars. Somaclonal variation was quantified at maturity for seven yield-related parameters on fertile plants cultivated in the absence of-salt. For most parameters, R-0, R-1 and R-2 plants performed less than the initial cultivar but their variability also strongly increased and maximal values were often recorded on tissue culture-derived plants. Somaclonal variation depended on genotype, morphological parameter analysed, NaCl dose and stage of stress imposition. Exposure to NaCl during proliferation phase decreased the extent of somaclonal variation in R-0 comparatively to plane regenerated from non-stressed calli, but it was still higher than somaclonal variation observed when NaCl was added to regeneration medium. Subsequent evolution of somaclonal variation in R-1 and R-2 populations suggested that NaCl added to proliferation medium mainly restricted the physiological component of somaclonal variation while such a trend was not observed when NaCl was added to regeneration or rooting media.