A physiological evaluation of the enhanced osmotic stress tolerance of an asymmetric somatic hybrid introgression line SR3 between bread wheat and couch grass

Abstract

The cultivar, Shanrong No.3 (SR3) is the product of an asymmetric somatic hybrid between the bread wheat (Triticum aestivum L. cv. Jinan 177) and couch grass (Thinopyrum ponticum). After seedlings of SR3 and Jinan 177 were hydroponically subjected to osmotic stress, the accumulation of proline and sugars, the activities of a number of antioxidant enzymes and the relative expression levels of LEA and DHN-like genes in roots and leaves were examined. Leaf water potential and relative water content were also determined. SR3 leaves were more effective in accumulating proline and soluble sugar than those of Jinan 177, and their osmotic potential was significantly reduced in response to the applied osmotic stress. The mean increase in the activities of SOD, POD and APX in the stressed root and leaf of SR3 were higher than those of Jinan 177, as were the relative expression of two LEA genes and two DHN genes. Overall, SR3 achieved enhanced stress tolerance via an improvement in its osmoregulation, an increase in its enzymatic antioxidant activity and an enhancement in its cellular protection.

Key words: Somatic hybrid, introgression, cultivar-Shanrong No.3, water stress, osmolytes, antioxidant enzymes, semi quantitative RT-PCR.