Responses to osmotic and NaCl stress of wheat varieties differing in drought and salt tolerance in callus cultures

Abstract

Callus cultures of four varieties of wheat ( Triticum aestivum L.) were maintained on media containing 0, 0.5 and 0.7 M mannitol as osmotic condition, and six varieties were grown on media containing 0, 0.1, 0.2 and 0.34 M NaCl as saline condition. To reveal genotype-dependent adaptive responses, growth, total N, total P, and changes in the internal Na + and K + concentrations were determined. Under osmotic stress, the calli derived from the drought tolerant varieties, Plainsman and Saberbeg showed less reduced growth as compared to the sensitive varieties, Cappelle Desprez and Chinese Spring. Furthermore, low levels of total N and P, and high initial intracellular K + concentration were recorded in the calli of the resistant varieties. In contrast, the sensitive varieties elicited increased N and P levels, as well as low initial intracellular K + concentrations. Under salinity at 0.1 M NaCl, Plainsman, Caribo and the salt tolerant Sakha-8 maintained their growth rate, while an inhibition was observed in Cappelle Desprez, Chinese Spring and Regina. Total N and P levels were similar to that under osmotic stress. Plainsman maintained low and constant levels, while a slight increase was recorded in the drought and the salt sensitive Regina. Cappelle Desprez and Regina excluded Na + , whereas the rest of the varieties accumulated it. Only Sakha-8 and Caribo elicited enhanced intracellular K + concentration with increasing salinity, while in the other varieties it remained unchanged or decreased. Patterns of changes in water status, as shown by the fresh weight to dry weight ratio, were also characteristic for the genotypes. It is concluded that the growth parameters, total N, P, and changes in Na + and K + concentrations can be considered as factors of adaptive value under osmotic and/or salt stress conditions. Results suggest that callus cultures may give genotype dependent responses under osmotic and salt stress conditions.