In vitro selection of birch for tolerance to salinity stress

Abstract

In vitro modelling of stress is one of the promising avenues for plant breeding for tolerance to negative environmental factors. In this study we examined the effect of NaCl (0.5%) on callusogenesis and morphogenesis of stem explants of different birch genotypes: Betula pendula Roth, B. pendula Roth var. carelica (Mercklin) Hämet-Ahti, B. pendula f. ‘dalecarlica’ (L.f.) Schneid., B. pubescens Ehrh. In our experiments we used pre-selected microclones from our in vitro collection on NaCl (0.2-1.0%) selective media. The clones were contrasted by the degree of their sensitivity to salinity (so-called ‘stable’ and ‘sensitive’ microclones). With the use of stem callus cultures we identified informative, simple and reproducible indicators for the selection of salt-tolerant genotypes. Among these indicators were the frequency of callus formation and the viability of callus cultures, which were significantly higher in ‘stable’ group of microclones. Polyploid birch clones (2n=4x=56, 2n=3x=42) were more resistant to salination compared to diploid clones (2n=28). Our study has shown that the selection of salt-tolerant birch lines can be based on the plants’ genetic diversity presented in the collection (various species, varieties, hybrids, polyploids) and manifested in the process of in vitro cultivation, as well as in the cellular heterogeneity of callus cultures.