Genetic Analysis And Relative Gene Cloning For Salt Tolerance In Rice

Salt stress damages the functions of plasma membrane and induces stoma-closing, photosynthesis-decreasing, over energy-consuming and unbalance of inorganic ion absorbing in plants. Plant salt tolerance was genetically controlled by mixed inheritance mode with major plus polygenes. Many salt-inducible genes have been cloned, and there are some hypotheses on molecular mechanisms of salt-stress tolerance, such as osmotic adjustment, salt-resistence, compartmentation, regulated potassium transport system, regulated water channel and converted photosynthesis pathway. Some salt-inducible genes have been transformed into plants, and it was evidenced that exogenous gene can enforce the ability to tolerate salt stress.Rice is grown widely in the world with moderate sensitivity to salinity. The most effective approach to improve rice salt tolerance is breeding salt tolerance varieties. In order to breed salt tolerance cultivars genetic analysis and relative gene cloning for salt tolerance in rice must be studied. A recombinant inbred lines(RILs) population of 248 lines derived from a cross of Jiucaiqing(japonica)/IR26(indica) by the single seed descent method was used to conduct genetic analysis and relative gene cloning for salt tolerance in rice. The main results are followings:1. Genetic analysis for salt tolerance in rice seedlingsThe salinity tolerance rating, relative plant height, relative dry weight of shoot, relative dry weight of root and Na~+/K~+ of root were evaluated under 0.5% and 0.7% NaCl stress, then genetic analysis of these traits were identified. Jiucaiqing and IR26 with various salt tolerance were identified under two NaCl concentrations, the salt tolerance of Jiucaiqing is better than IR26. The genetic analysis results showed that salinity tolerance rating, relative plant height, relative dry weight of shoot and relative dry weight of root, Na~+/K~+ of root were genetically controlled by genetic mode of two inhibiting effect major genes(B-l-9), two complementary effect major genes plus polygenes (E-1-7) , two linkage additive effect major genes plus polygenes (E-2-6) , three additive epistasis major genes plus...