Can the drought tolerance traits of Ae. biuncialis manifest even in the wheat genetic background?

Abstract

The physiological responses to water stress induced by PEG were investigated in Aegilops biuncialis (Vis.) genotypes which differ in the annual rainfall of their habitat (1050, 550 and 225 mm/year) and in Triticum aestivum (L.) wheat genotypes differing in drought tolerance, in order to find Ae. biuncialis accessions suitable for improving wheat drought tolerance through intergeneric crossing. A decrease in the osmotic pressure of the nutrient solution from –0.027 MPa to –1.8 MPa resulted in intense water loss, a low extent of stomatal closure and a decrease in the intercellular CO2 concentration (Ci) in Aegilops genotypes originating from dry habitats, while in wheat genotypes high osmotic stress induced increased stomatal closure, resulting in a low level of water loss and high Ci. Nevertheless, under saturating light at normal atmospheric CO2 level, the rate of CO2 assimilation was higher for the Aegilops accessions under strong osmotic stress than for the wheats. Moreover, in the wheat genotypes, CO2 assimilation exhibited less or no O2 sensitivity. These physiological responses were manifested in changes in the growth rate and biomass production, since Aegilops (Ae550, Ae225) genotypes retain a higher growth rate (especially in the roots), biomass production and yield formation after drought stress than wheat. On the basis of the results it seems that Aegilops genotypes originating from a dry habitat have better drought tolerance than wheat, making them good candidates for improving the drought tolerance of wheat through intergeneric crossing.