The Characterization And Function Analyses Of Rice ERF Protein OsERF109

Rice is an important food crop and its water consumption accounts for70%of agricultural wateruse in China, however, China is a country which is of water-shortage--the per capita fresh waterresources is less than a quarter of that in the world and China is a rainless and uneven-rainfull contry,even in rainfall-rich southern provinces, seasonal droughts occur frequently. Thus, drought stress causedby water scarcity is an important limiting factor affecting rice high yield and stable production,improving the drought tolerance of rice is an important topic that needs to be solved. Through long-termresearches, we find that making full use of biotechnology and identifying the stress-tolerant generesources for the stress-tolerant rice varieties have become an important way to solve the problem, so itis significantly important to identify drought stress related genes and to study the molecular mechanismsin drought stress response.Plants form a stress defense system in the long process of evolution. In abiotic stress, regulationof plants could occur in multiple levels including chromatin, transcription and post-transcription. Ofthem, regulation of transcription factors in transcriptional level plays a significant role. AP2/ERFtranscription factor is known to be unique in plant. Increasing investigations have revealed thatmembers of AP2/ERF family are involved in drought reponse in multiple molecular pathways. In thepresent research,12up-regulated ERF genes in reponse to drought were identified, according to ricegenome-wide genechip analyses. We choosed one of the genes named OsERF109to make analyses ofcharacterization and function. The result showed that OsERF109is induced by drought, NaCl, ABA andACC. The OsERF109is expressed in leaf, root and sheath in the tissue expression analyses, showing thehighest in leaf, next in root and the lowest in the sheath. OsERF109is of self-activation, suggesting it isa transcriptional activator through transactivation in yeast. Transgenic plants overexpressing OsERF109(OE) resulted in deduced tolerance to drought stress while the OsERF109RNA interfering transgeniclines (RI) conferred enhanced tolerance to drought stress in rice seedling, indicating that OsERF109involved negatively in the drought response. The experiment of water loss rate of isolated leavesshowed that water loss rate in OE lines were lower than control, in contrast, higher in the RI thancontrol, indicating that OsERF109maybe regulate drought tolerance throught water loss. Expression ofdrought-related genes showed that OsERF109had impact on OsPIP genes. Moreover, overexpression ofOsERF109decreased the expression of ethylene biosynthesis genes and proline biosynthesis gene.Overexpression of OsERF109up-regulated the expression of negative factors OsAP2-39and OsERF3.