Abstract:In our study,MhGlu,a β-1,3-glucanases gene of Malus hupehensis was cloned from leaves of M.hupenhensis treated with NaCl,PEG-6000 and ABA at 4 ℃ by RT-PCR.A plant binary expression vector of MhGlu was constructed.The vector was transformed into tobacco through Agrobacterium-mediated method.PCR and RT-PCR results showed that four transgenic tobacco lines T6,T8,T11 and T18 were obtained.The function of MhGlu was further analyzed with the transgenic tobacco lines T6,T8 and wild type tobacco plants (WT).Results showed that:(1)The expression of the gene in M.hupehensis was monitored in a 48 h course after treated with NaCl,PEG-6000 and ABA at 4 ℃,respectively.Semi-quantitative RT-PCR revealed that expression of MhGlu was induced by NaCl,PEG-6000 and ABA at 4 ℃ treatment in both potted seedlings and seedlings cultured in vitro.Treated by NaCl and PEG-6000,the expression of MhGlu gene increased gradually over time;while ABA treatment at 4 ℃ up-regulated MhGlu 4 h post treatment,the expression decline at 12 h,then reached to maximum at 48 h.(2)Compared with the WT plants,several pathogenesis-related genes (PRs) in tobacco (NtPR1,NtPR2,and NtPR3) were up-regulated in tobacco plants with overexpression of MhGlu,detected by semi-quantitative RT-PCR.(3)Being infected with Botrytis cinerea,T6 and T8 lines of transgenic tobacco plants showed stronger tolerance to B.cinerea than nontransgenic plants.(4)Overexpression MhGlu appeared to improve the photosynthetic characteristics of transgenic tobacco.The net photosynthetic rate (Pn),the transpiration rate (Tr) and stomatal conductance (Gs) of transgenic plants were increased compared with that of controls,and the difference was significant.The Pn and Tr of T8 were significantly higher than that of T6,while the difference of Gs between T8 and T6 was not significant.Overall,the overexpression of MhGlu can induce the expression of PRs genes,active the protection mechanism with photosynthetic characteristics and enhance the resistance to B.cinerea of tobacco.