Transformation of DRO1, OsNAC5, OsEXPA8 genes in order to improve root architecture and drought tolerance in rice

Root architecture modification can increase grain yield and seed quality. These can be achieved by better anchorage of the plant in soil, more effective use of water and nutrients, and through biosynthesis of amino acids and hormones. These will result in more effective use of nutrients and drought tolerance. Considering drought stress in Iran, production of drought tolerant plants is important. In this study three genes involved in modification of root length, number, thickness and growth angle were cloned into a construct for Agrobacterium-mediated transformation of rice plant. Genes OsEXPA8, OsNAC5, and DROI from native cultivars of rice were cloned under the control of constitutive and root specific promoters; afterwards, they were placed in T-DNA region of Agrobacterium-mediated transformation binary vector. The resulted construct, pUhrN5ExDro, was transferred into Agrobacterium tumefactions strain EHA105 and used for transformation of immature embryo of rice cultivar Hashemi. Selective medium containing 50 mgl-1 hygromycin B was used for selection of transgenic plants. Construct specific and gene specific PCR confirmed three putative transgenic lines and one copy of transgene were detected in one of them using Real time-PCR. Inverse PCR revealed that T-DNA was integrated in chromosome 10 of this rice event. Comparison of the phenotype and root structure of the transgenic plants with the control in the Root Box and in the same growth conditions showed that transgenic plants displayed stronger root phenotype compared with non-transgenic ones. The resulting multi-genic construct can be used for other crops transformation in order to root structure modification and drought tolerance. It is hoped that the production of rice with modified root structure can increase drought tolerance in this important crop and reduce water consumption in rice cultivation.