Overexpressing a novel RING-H2 finger protein gene, OsRHP1, enhances drought and salt tolerance in rice (Oryza sativa L.)

RING (really interesting new gene) zinc-finger proteins have important regulatory roles in the development of a variety of organisms. In the present report, a full length cDNA encoding a novel RING-H2 finger protein from rice, designated as OsRHP1, was isolated and characterized. OsRHP1 encodes a small protein (167 amino acids) with two N-terminal trans-membrane domains and a canonical RING-H2 zinc-finger motif located at the C-terminus. Ten putative homologs of OsRHP1 harboring one canonical RING-H2 finger domain exhibit in other plant species. In our work, OsRHP1 was expressed ubiquitously in various tissues, but its transcript is accumulated more in mature leaf. Compared with wild-type (WT) rice plants, transgenic plants overexpressing OsRHP1 exhibited more tolerance to drought and salt stress. Meanwhile, the transgenic T2 lines showed a significant increase of endogenous ABA content in normal condition. When subjected to drought and salt stress, much stronger accumulation of ABA was detected compared with WT. Furthermore, a significant increase of transcriptional expression, of five ABA biosynthesis or ABA-mediated response genes, OsNCED, OsZEP, OsAAO, OsABI5, OsABF2, OsLEA3-1 were observed in the transgenic plants under drought and salt stress condition. These results demonstrate that overexpression of OsRHP1 substantially enhances drought and salt tolerance through increased ABA level and enhanced ABA-mediated stress response.