Ploidy stability of Oryza sativa. L cv IR64 transformed with the moth bean P5CS gene with significant tolerance against drought and salinity


Abstract: Rice is one of the world's most important crops. Thus, it is necessary to improve it by genetic transformation. IR64 is a high-yielding and disease-resistant variety, but it is sensitive to abiotic stresses, mainly salinity and drought. Therefore, an efficient transformation system is a prerequisite for transforming this indica rice with a stress-tolerant gene, the potent osmolyte proline-coding P5CS gene of Vigna aconitifolia. Successful transgene integration was confirmed by polymerase chain reaction (PCR) and Southern blot analysis. A Mendelian pattern of transgene inheritance was also observed in the progeny plants. The individual transformants expressed significant tolerance over wild-type control plants, as exhibited by NaCl tolerance, lipid peroxidation levels, and total chlorophyll content. Percentage of germination, height, and weight of the plantlet at 400 mM mannitol stress was 60%, 8.1 cm, and 92.5 mg, respectively. Total chlorophyll retention and malondialdehyde content at 200 mM NaCl stress was 65.3% and 8.2 n mol g-1 FW, respectively. These results revealed the abiotic stress tolerance conferred by $\Delta$1-pyrroline-5-carboxylate synthetase. Additionally, flow cytometry analysis confirmed the absence of somaclonal variation. Hence, an efficient genetic transformation can be accomplished in other indica rice cultivars by using this protocol.

Keywords: IR64, drought, P5CS, Agrobacterium transformation

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