There is a decrease in the land available for rice cultivation due to the rapid conversion to urban uses. Subsequently, acid soil could be an alternative land cultivating rice, but will require the use of aluminum (Al)-tolerant rice varieties. This Al tolerance trait is genetically controlled, and there is a need to discover more genes needed to develop Al-tolerant rice. Therefore, the objective of this study was to clone and characterize a novel Al tolerance gene isolated from a local cultivar of Indonesian rice. The gene cloning was conducted based on the rye/rice microsynteny relationship. In addition, the root growth and gene expression analyses were performed to verify the role of the gene on Al tolerance in gene-silenced rice and in overexpressed transgenic tobacco. The results showed an Al tolerance candidate gene, OsGERLP, was successfully cloned from rice cv. Hawara Bunar, with its gene encoding a protein similar to a bacterial ribosomal L32 protein. Additionally, the analysis showed that low gene expression caused the gene-silenced rice to be sensitive to Al, while high expression induced the Al tolerance in transgenic tobacco. Furthermore, it was discovered that the gene expression level in both plants was in line with the lower expression of the OsFRDL4 gene in the silenced rice and the high expression of the MATE gene in transgenic tobacco also with the higher citrate secretion from transgenic tobacco roots. In conclusion, the OsGERLP gene could act as a regulator for other Al tolerance genes, with the potential to develop Al-tolerant rice varieties.
Keywords: Aluminum tolerance; Citrate; Gene silencing; Transcription factor.
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