Ectopic Overexpression Of Rice OsAQP Improve Abiotic Stress Resistance In Arabiopsis

Water channel protein is the rapidly translocation channel that widely exist in plant and animal cells.The research has showed that Water channel protein has the function including promoting plant growth and development,cell proliferation,pollen development,seed germination,abiotic stress responses,hormone response and so on.We had cloned aquaporin from the rice seedling,named OsAQP and the semi-quantitative RT-PCR analysis showed that OsAQP might be associated with rice abiotic stress response,which function was not yet clear.In this study,the real-time quantitative PCR method was performed to detect the influence that two kinds of abiotic stress responses and seven kinds of plant hormones had on OsAQP gene in rice seedlings.The results showed that drought and high salt could induce to increase the quantity of OsAQP gene expression and its expression patterns were different.The result that simulated drought treatment detected revealed that the gene existing in the root part is significantly higher than that existing in aerial parts.The expression levels of genes had reached a maximum and equaled 12.87 times before treating and after drought treatment 5 h,about and maintained 9.6-10.6 times after treating 10 h and 24 h.Though the expression level of gene on the ground had raised,the amplitude was small.The expression level of gene was no more than three times compared with the level at the time that treating about 0.5 h,5 h,10 h and 24 h.The peak of the treatment appeared at the time after treating over 0.5 h and the increase rate just arrived 2.39 times.The result that the salt treatment was similar with the result that treated by the drought stress.The peak of gene expression level in the root appeared in the 5 h and 10 h,which up-regulated about 9.68 times and still remained 6.7 times after 24 h.Meanwhile the expression level of gene on the ground changed not significantly compared with in the root.Though the expression level of gene raised,the peak expression level of gene just raised 3.15 times after treating 10 h.In order to understand the relationship between OsAQP response gene and a variety of hormones,we used 6-BA,MeJA,ABA,BR,IAA,GA,MeJA7 kinds of hormones to treat the rice seedlings and detected the express characteristics.The result showed that the gene expression level both up-regulated in root and on the ground and showed the different expression regulation.Similar with the abiotic stress processing result,the change in the root is significant while is not obvious on the ground.The treatment with MeJA in root made OsAQP expression up-regulated the most,equaling 21.08 times to treatment before.Though the gene expression level on the ground also had raised,the amplitude was small,the treatment with GA makes the maximum rise in gene expression on the ground,up-regulated about 5.84 times.The treatment with BR on the ground had little influence,equaled about 1.05 times to treatment before.The result showed that the expression level of gene OsAQP was influenced by the various hormones of 6-BA,MeJA,ABA,BR,IAA,GA,MeJA,the drought and high salt.In order to study the relationship between OsAQP gene and the abiotic stress,recombinant DNA technology was constructed the overexpression vector pCAMBIA1302-OsAQP-GFP which was controlled by CaMV 35 s promoter.The coexpression vector was migrated to Arabidopsis and screened the homozygous transgenic arabidopsis thaliana plants.We used the transgenic arabidopsis to detected the influence that made by the treatment with drought and salt stress on seed germination and seedling growth.We found that the germination time of transgenic arabidopsis seeds obviously was earlier than wild type about 1 or 2 days in a simulated drought(300 mM mannitol)and high salt stress(200 Mm NaCl)conditions,which illustrated that the over expression of OsAQP gene can improve the tolerance of the germination time of transgenic arabidopsis to drought and salt stress.When the concentration of mannitol and NaCl concentration reached 400 mM and 250 mM respectively,the wild type and transgenic arabidopsis didn't sprout,suggesting that the over expression of the OsAQP gene can improve seed germination in arabidopsis during drought and high salt tolerance.To observe the growth of plants under the condition of high salt and drought condition,the results showed that transgenic arabidopsis grew better and the root was more longer than the wild type at the time when cultured by 15 days.Detection the contents of MDA in the leaf,we found that there had little difference between the two materials.The content of MDA between transgenic Arabidopsis had a significant difference and lower than the wild type after the treatment by high salt and drought,which showed that the over expression of OsAQP gene can improve the tolerance of transgenic Arabidopsis to high salt and drought condition.To study the function of OsAQP gene in the growth of rice,recombinant DNA technology was constructed controlled by corn plant of ubiquitin promoter overexpression vector pCAMBIA1390–Ubq– OsAQP to study the genetic and transformation of rice and screen 10 the T0 generation plants.The agronomic characters analysis showed that there was significant different between thousand seed weight and plant height about plant having the over expression OsAQP gene.There was no significant difference in spike length,effective tiller number,primary branch number,total grain number,grain number,seed setting rate and the total number of tillers.This study examined the influence that the drought,high salt,and ABA,JA,SA,MeJA,IAA,BR and GA on OsAQP gene expression.In the meantime,we used biotechnology to identify the gene function to abiotic stress.We found that that the over expression of OsAQP gene can improve the tolerance of transgenic Arabidopsis to high salt and drought condition,Then we construct the rice which had the over expression of OsAQP gene and finish the screen of T0 generation rice,which laid the foundation for further studying the function that OsAQP gene in the growth rice and improve the potention that the tolerance that the rice to non-biological stress.