Rice (Oryza sativa) is sensitive to salt stresses and cannot survive under low salt conditions, such as 50 mM NaCl. In an attempt to improve salt tolerance of rice, we introduced katE, a catalase gene of Escherichia coli, into japonica rice cultivar, Nipponbare. The resultant transgenic rice plants constitutively expressing katE were able to grow for more than 14 days in the presence of 250 mM NaCl, and were able to form flower and produce seeds in the presence of 100 mM NaCl. Catalase activity in the transgenic rice plants was 1.5-to 2.5-fold higher than non-transgenic rice plants. Our results clearly indicate that simple genetic modification of rice to express E. coli-derived catalase can efficiently increase its tolerance against salt stresses. The transformant presented here is one of the most salt-tolerant rice plants created by molecular breeding so far.

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In an attempt to improve the salt tolerance of rice, we introduced katE, a catalase gene of Escherichia coli, into the indica rice cultivar Kasalath. Transformation was carried out using Agrobacterium tumefaciens strain EHA101 harboring a binary vector pIES6/Hm/katE which contains genes for catalase katE, hygromycine resistance gene HPT and kanamycin resistance gene NPTII in the T-DNA region. With the inclusion of acetosyringone, higher amount of transgenic cells and regenerated plants were obtained. Transformation was confirmed by PCR with katE and HPT primer. Transgenic plants at a very young stage (three -four days) were able to grow up to 15 days in 100 mM NaCl solution and seven days in 250 mM NaCl solution whereas control plants died within five days in 100 mM and seven days in 50 mM NaCl. Plants stressed for four weeks could survive for a long time and were able to flower. Different morphological characters varied in transgenic compared to control plants. Introduction of katE gene significantly improved the salt tolerance of the transgenic indica lines which could mature and set seed under stress.

Rice is one of the most important food crops in the world. It is greatly affected by various abiotic stresses. Among them, to improve the complex stress salinity we introduced a desired gene katE, a catalase gene of Escherichia coli, and reporter gene GUS into the indica rice cultivar Kasalath. Plant survival under different salt water concentration was checked. Transformation was carried out using Agrobacterium tumefaciens strain EHA101 harboring a binary vector pIES6/Hm/katE and pIG121/ Hm/ GUS which contains genes for catalase katE, GUS gene, hygromycine resistance gene HPT and kanamycine resistance gene NPTII in the T-DNA region. Transformation was confirmed by PCR with katE and GUS primer. Transgenic plants at very young stage (3 days) were able to grow up to 15 days in 100 mM NaCl solution and 7 days in 250 mM NaCl solution where as non transgenic plants could not survive even up top 5 days in 100 mM condition and 7 days in 250 mM NaCl concentration. Twenty eight days matured plants could survive and were able to form iflorescence. Here a single gene introduction significantly improved the salt tolerance of this crop rice. DOI: http://dx.doi.org/10.3329/bjpbg.v20i2.17029