Improving Drought Resistance by Introduction of the Proline Synthesis Gene P5CSA into Inbred Rice Lines as a New Genetic Resource for Breeding Programs

Abstract

This research was aimed to identifying the P5CS gene involved in the drought stress mechanism in upland rice lines which is candidate as new genetic resource for breeding programs. The plant material consisted of 19 breed lines: Salumpikit and IR20 varieties, drought-tolerant and sensitive, respectively. The experiment consisted of 4 stages, including the evaluation of drought stress with 20% PEG 6000 (-0.58 MPa) in the germination and nursery phases, the vegetative phase, and the expression analysis of the P5CS gene. The results showed that the PEG inhibited the growth of roots, shoots, and the ratio of roots to shoot in the germination and nursery phases of all the tested lines, while the Salumpikit and IR20 varieties were confirmed as drought resistant and sensitive, respectively. The proline content under drought stress was significantly different in the lines tested, while Salumpikit and IR20 were confirmed to have high and low proline content, respectively. The proline content in several lines, such as G4, G6, G8, G10, G12, G13, G14, G15, and G17, exceeded the content in the Salumpikit variety. The P5CS gene was amplified in PCR analysis and expressed in the consistency of proline. It was found that the lines of G4, G6, G8, G13, and G17 showed tolerance to drought stress, had high STI values, and showed recovery ability and proline content. These lines have the potential to be released as candidates for new varieties. In addition, these lines have great potential as a new genetic source for upland rice breeding programs.