Over-ekspresi gen OsDREB1A guna perbaikan toleransi cekaman kekeringan pada padi

Abstract

Drought is a major factor that influence the growth and productivity of rice. Drought tolerant rice varieties are needed to increase rice production. Development of improved rice varieties can be done through classical breeding and genetic transformation. The research objective was to obtain rice plants containing the construct 35S::OsDREB1A. Agrobacterium tumefaciens mediated transformation of rice cv. Nipponbare using OsDREB1A gene under the control of CAMV 35 promoter produced 81 putative transgenic rice plants (T0) positively containing the transgene based on PCR analysis. The plant height, panicle number, panicle length, and the grain number of transgenic plants were in general lower than the Nipponbare wild type. T1 seeds from selected genotypes were screened for hygromycine resistence, and rice seedlings were evaluated for tolerance to drought stress in the glasshouse, based on the standard evaluation system for rice (IRRI 1996). Five independent transgenic rice plants were identified to be tolerant to drought stress. Molecular characterization using Southern hybridization showed that these plants had 2- 4 copies of transgene. Physiological analysis showed that the drought avoidance is the possible mechanism of adaptation to drought of the transgenic plants. The drought tolerant transgenic plants were crossed to Indonesian elite rice cultivars (Ciherang, Batutegi, Code, and Konawe). Glasshouse evaluation showed that F1 transgenic plants derived from cultivars Batutegi, Code, and Konawe were more tolerant to drought than their wild-type counterparts. F1 transgenic plants were backcrossed into corresponding elit rice cultivars, and PCR analysis showed that those plants contained the transgene. These results showed that 35S::OsDREB1A could be transferred and inherited to elite rice genotipes through crossing. The new drought tolerant germplasms generated in this research can be useful materials for breeding program for improvement of drought tolerance on rice in Indonesia.