The Study Of Salt Tolerance Of ZmPIS Transgenic Cotton

Salt stress is an important abiotic stress that can significantly affect the growth and yield of plants. Saline-alkali land occupies a big proportion of the arable land resources in our country. Therefore, cultivating salt-tolerance plants become a hot topic that scholars concern on. In some extent, cotton is a salt-tolerance plant and it is known as "the pioneer crops of saline-alkali land". Cultivating higher salt-tolerance cotton will help to increase farmers’income, develop saline-alkali land and solve the problem of "contending soil between grain and cotton" and will be good for the sustainable development of agriculture.ZmPIS gene is cloned from maize, and it encodes the phosphatidyl inositol (PI) synthetase. PI is not only an important part of the plant cell membrane lipid but also it is the start substance of PI signaling pathway. This pathway is closely related to the Ca2+ cascade signaling pathway and the phosphatidic acid (PA) signaling pathway and it plays an important role in response to salt stress.This work tests the ZmPIS transgenic cottons’salt tolerance through the physiological and chemical experiment and the germination experiment and probes the probably mechanism of salt tolerance of transgenic cottons through RNA-seq.We use the Lu 1138 cotton (the control strain) and three ZmPIS transgenic cotton strains as the material of the physiological experiment. Tested the relative water content, the degree of ion leakage, the osmotic potential and the antioxidant enzymes activity and the content of proline of these samples that before salt treated and after 250mM salt solution treated 1 day,7 days,14 days and 21 days, founded that transgenic strains had higher relative water content, higher antioxidant enzyme activity. heigher soluble sugar content, higher proline content and lower membrane damage degree than the control material. The comparison of net photosynthetic rate and photosynthesis fluorescent parameters tells that the transgenic strains had higher photosynthetic than control strain.Through the germination rate experiment, in OmM salt solution treated tray, germination rate and seeding growth situation had no difference between different materials. In 50mM salt solution treated tray, the germination rate had few difference and the seeding growth situation had been affected. In 100mM salt solution treated tray, the germination rate and seeding growth situation had been affected seriously, but the situation of transgenic strains were better than control strain.The above results suggested that ZmPIS transgenic strains have higher salt tolerance than the control strain.Through the physical experiment and germination experiment, chose the best transgenic strain and control strain to do the RNA-seq analysis. By the RNA-seq analysis, we found that ZmPIS gene affected the expression of genes related to calmodulin and DGK activity in PI signaling pathway, and it also affected the expression of genes related to synthesis of fatty acid, besides, it changes the expression of genes related to amino acid synthesis and metabolism. In addition, the key enzyme gene of ABA synthesis is also influenced by the ZmPIS gene. Many other genes related to hormones’synthesis and metabolism process and signaling pathways are also changed. These changes may be the reason why transgenic plants have higher salt tolerance.