Abstract:

In order to investigate the effects of ABA treatment on accumulation of the soluble proteins and dehydrins in leaves of ornamental crabapples under soil drought stress, we selected a drought resistance cultivar, Malus spp.cv. 'Royalty’ and a drought susceptible cultivar,Malus spp.cv. 'Red Splendor’ as plant materials, ABA solution or water (served as control) was sprayed on leaves of the plants subjected to soil drought. The relative water content (RWC), relative electricity conductivity (REC),soluble protein content(SPC), and the expression of soluble proteins and dehydrins in ornamental crabapples leaves were measured during the drought process. Our results indicated that for M. spp.cv. 'Royalty’ leaves, pretreated with ABA RWC increased significantly, REC and SPC decreased, while the indices in the ABA-pretreated M. spp.cv. 'Red Splendor’ leaves changed in the oppositely. SDS-PAGE analysis showed that ABA treatment resulted in the modification of molecule soluble proteins of 14.8, 18.0, 46.2, 50.9, 78.1 and 145.2 ku in 'Royalty’ leaves and 14.4, 18.0, 32.8, 46.2, 89.6 and 141.0 ku in 'Red Splendor’ leaves respectively. Immunoblotting results indicated that drought stress induced the expression of dehydrins 14.8 and 51.0 ku in 'Royalty’ leaves, and 14.4 and 32.8 ku in 'Red Splendor’ leaves respectively. Moreover, ABA treatment induced significantly these dehydrins accumulation of two cultivars leaves at 0 d of soil drought treatment, and inhibited the dehydrins accumulation of 14.8 ku and 51.0 ku in 'Royalty’ leaves and 14.4 ku in 'Red Splendor’ leaves in 7 d after soil drought treatment. In conclusion, ABA treatment was able to induce expression of dehydrins under non-drought conditions in leaves of ornamental crabapples.However, ABA inhibited accumulation of drough-induced dehydrins, when the plants were subjected to drought stress, which had a positive correlation with the drought resistance of different cultivars.

Key words: ornamental crabapples, ABA, drought stress, soluble proteins, dehydrin