Mohammad Ali Sheikh Beig Goharrizi, Atta Dejahang, Koroush Vahdati, Masoud Tohidfar, Ali Izadi Darbandi, Carrillo Nestor and Mohammad-Reza Hajirezaei
DDepartment of Genetic and Biotechnology, Russian Timiryazev State Agrarian University, Moscow, Russia
Walnut somatic embryos were transformed with two strains of Agrobacterium tumefaciens, LBA4404 and C58 respectively harboring pBI121 with Gus and neomycin phosphotransferase (nptII) genes and p6u-ubi-FVTI plasmids containing the fld gene and hpt gene as reporter and selectable markers, Also the transgenic and non-transgenic somatic embryos of Persian walnut were exposed to four salinity levels (0, 50, 100 and 200 mM NaCl) and four different levels of osmotic stress (0, 1.5, 5 and 10% PEG) treatments. After 20 days, number of survived, secondary and cotyledonary somatic embryos, as well as fresh and dry weights of embryos were evaluated. In addition, the transgenic and non-transgenic plantlets were subjected to 200 mM NaCl. In both experiments, the main effects of fld- transformation and stress treatments on evaluated parameters were significant. Transgenic somatic embryos showed no significant differences in measured parameters at 0 and 200 mM NaCl and 0 and 1.5% PEG as compared to non-transgenic ones. Significant differences in measured parameters of transgenic vs. non-transgenic somatic embryos were observed at 50 and 100 mM NaCl and 5 and 10% PEG. With medium supplemented with 200 mM NaCl non-transgenic plantlets showed complete necrosis and died after 10 days, while transgenic lines continued their growth until 45 days. Our results show clearly that over-expression of fld partially increased stress tolerance in fld transformant lines of walnut and that expression of this specific cyanobacterial protein constitute a powerful tool to improve plant fitness towards environmental adversities.
Keywords: Somatic embryo, transformation flavodoxin gene, walnut gene transformation, Salinity and osmotic stress tolerance in walnut.