The Negative Regulator Of ABA Responses, OsRACK1, Is Invovlved In Response To The Abiotic Stress In Oryza Sativa

The scaffold protein RACK1(Receptor for Activating C Kinase1) regulated different signal transduction pathyways ranging from cell division to environmental stress responses by interacting with diverse proteins.The protein sequence of RACK1was highly conserved in eukaryotes. RACK1A in Arabidopsis mediated hormonal responses and had a regulatory role in multiple developmental processes.It was proved that rack1α mutant had strong drought tolerance. Arobidopsis RACK1was defined as a negative regulator of ABA responses. In this study, we focused on the function of RACK1in the response to drought and salt stress by measuring plant physiology and microbiology methods. Over-expressing plants of RACK1, interference plants of RACK1and control were choosed.The main results were as followed:1.Significant differences in morphology and drought tolerance were observed among different genotypes investigated. Apperant differences in plant height、panicle length and the width of graints were observed between wild type and transgenic plants. Over-expressing plants of RACK] is hypersensitive to drought. The tolerance of interference plants of RACK1has the same as the control.Great differences were also detected in water loss of detached leaves among wild type and transgenic plants. Over-expressing plants of RACK] has high water loss rates than the control. The water loss rates of interference plants of RACK1have the same as the control.2. Exogenous ABA had effects on ABA marker gene in transgenic and wild type plants.The results of Real-time PCR analysis showed that there were significant differences in LEA family expression under ABA treatments between different genotypes. The expression of over-expressing plants of RACK] had less than wild type.3. ABA marker gene was effected by the treatment of20%PEG in transgenic and wild type plants. The results of Real-time PCR analysis showed that there were significant differences in LEA family expression under drought stress treatments between different genotypes. The expression of over-expressing plants of RACK1had less than wild type.4. Salt stress had effects on ABA marker gene in transgenic and wild type plants. The results of Real-time PCR analysis showed that there were significant differences in LEA family expression under salt treatments between different genotypes. The expression of over-expressing plants of RACK1had higher than the wild type.5. The leaf ABA contents of wild type and transgenic rices were increased qucickly and significantly under treatments of20%PEG. During drying period, the accumulation of ABA in over-expressing plants of RACK1was significantly lower than wild type.These results suggested that RACK1was invovled in the accumulation of ABA.6. The leaf ABA contents of wild type and transgenic rices are increased qucickly and significantly under treatments of200mM NaCl. The accumulation of ABA in over-expressing plants of RACK1was significantly lower than wild type.These results suggested that RACK1was invovled in the accumulation of ABA.According to the above results, it was suggested that OsRACKl negatively regulated the drought-resistence of rice plants. OsRACK1was invovled in ABA signaling pathway and was a negative regulator of ABA responses.