实验海洋生物学重点实验室知识库

Abstract
Porphyra yezoensis (P. yezoensis ) is one of the most important economically marine algae. In recent years, the quality of the P. yesoensis is reduced, which greatly affects the development of seaweed industry. The cultivation of best quality algae with stress resistance becomes the urgent need. Germplasm resource of high quality is the key point of breeding stress resistance species. However, the research on the breeding of marine algae started late, and the basic research of it is weak. At present, there is no physiological and molecular markers to screen the excellent germplasm resources. Therefore, it is important to find the key position of P. yesoensis in response to abiotic stress and develop the molecular markers. In this study, we focused on resistant breeding of P. yezoensis. More attentions were paid to determine the key position of resistance characteristics under salt stress in P. yezoensis and develop SSR markers for resistance characteristics of quantitative trait loci. In addition, the genetic diversity was extended by artificial mutation, all of which laid the foundation for the quantitative trait loci of the resistance traits. These results mainly include the follows:
 (1) The photosynthetic (PS) responses of P. yezoensis blades under salt stress were studied. Our results showed that when the effective photochemical quantum yield of PSII almost decreased to zero under high salt stress, while YI still had a relative high activity rate. PSII is therefore more sensitive to salt stress than PSI. These results demonstrated that under severe salt stress (120‰ salinity), the electro source of PSI was derived from a source other than PSII, and that stromal reductants probably supported the operation of cycle electron flow around PSI. Under salt stress, the starch content decreased and the soluble sugar levels increased. The G6PDH and 6PGDH (EC 1.1.1.44) activities increased, but the GAPDH activity decreased. Furthermore, the NADPH content increased, and NADH decreased, which suggested that soluble sugar entered the oxidative pentose phosphate pathway (OPPP). All these results suggested that NADPH from OPPP increases the cyclic electron flow around PSI in high intertidal macroalgae under severe salt stress.