Physiological Responses of Rice Seedling (Oryza sativa L.) to Salt-stress Cultured under in vitro Photomixotrophic and Photoautotrophic Systems

摘要

Physiological responses of crop species to salt-stress in conventional in vitro culture may be found some errors due to sucrose as a main carbon source, causing to erratic data. Seven-day-old in vitro seedlings were aseptically transferred to cultureunder photoautotrophic and photomixotrophic systems for 13 days, subsequently adjusted to 0 and 342 mM NaCl. The pigment degradation of seedlings grown in 342 mM NaCl was positively related to NPR reduction in both the photoautotrophic (r=0.84) and the photomixotrophic system (r=0.95). This resulted in low growth, as measured by leaf expansion, shoot height, root length, fresh weight and dry weight. Moreover, the NPR reduction of seedlings cultured with 342 mM NaCl was positively related to the low survival percentage for both the photoautotrophic (r=0.96) and the photomixotrophic system (r=0.98). Moreover, the phenotypic responses of photoautotrophic seedlings to salt-stress expressed a more realistic phenotype than the photomixotrophic system. Besides, the phenotypic expression of seedlings cultured under photoautotrophic system responded more sensitively to salt-stress than those photomixotrophic system. Therefore, study of the phenotypic responses of seedlings to salt-stress would make use of thephotoautotrophic system. This system should be a novel process for phenotypic expression of in vitro to salt stress.