A RADISH (RAPHANUS SATIVUS L.) E3 UBIQUITIN LIGASE GENE RHA2b ENHANCES SEED DORMANCY AND TOLERANCE TO PREHARVEST SPROUTING IN TRANSGENIC WHEAT (TRITICUM AESTIVUM L.)

The RHA2b gene from radish encodes a transcription factor that is involved in abscisic acid (ABA) signal transduction and is associated with seed dormancy and preharvest sprouting.RsRHA2b gene may have the function to improve dormancy and tolerance to PHS in transgenic wheat.The RsRHA2b gene was cloned and transferred into Zhengmai 9023 via Agrobacterium-mediated stem apex transformation.The results of RT-PCR and southern blot indicated that the RsRHA2b gene was integrated into the genomes of the wheat transformants.Seed dormancy and PHS tolerance was significantly enhanced in transgenic plants that stably expressed RsRHA2b.In addition, in the presence of 0.5 µmol/L ABA and 5 µmol/L ABA, a significant reduction in weight was found between the transgenic wheat plants and the non-transgenic Zhengmai 9023 plants.Furthermore, the expression of genes involved in RHA2b-mediated ABA signal transduction, such as ABI5, FUS3 and MAL, significantly increased at the second leaf stage in ABA-treated transgenic wheat plants.These results show that RsRHA2b improves dormancy and preharvest sprouting tolerance in transgenic wheat.