In this study, effects on physiological and biochemical indexes of gametophytic blades of an low nitrogen and phosphorus tolerance line (9-Ⅳ ) of Porphyra haitanensis under low nitrogen and phosphorus stress were observed.They were grown in medium with low content of nitrogen and phosphorus for 0,2,4,6,8 and 10 days.Changes in three quality indexes were measured, including the contents of pigment,crude protein and free amino acids.Results showed that all the three quality indexes of P.haitanensis were significantly declined under low nitrogen and phosphorus stress.Furthermore, changes in physiology also were measured, including free radical content, H2O2, malondialdehyde (MDA)and proline levels, and the activities of superoxide dismutase, peroxidase, and catalase.These physiological indexes were all presented as dynamic changes in the stress days.Based on these data,the physiological changes within the 9-Ⅳ blades were as follows:low nitrogen and phosphorus stress→cell membranes were damaged by oxidation and MDA levels increased→cells received signals of excessive ROS→antioxidation and osmoregulation systems began to clean out excessive ROS→free radical levels declined.Our results laid a foundation for understanding the principle of low nitrogen and phosphorus tolerance in P.haitanensis, and provided some directions for future breeding.%以坛紫菜耐低氮(N)、磷(P)品系9号Ⅳ叶状体为材料,研究了低N、P胁迫不同时间水平对坛紫菜品质及自由基含量、过氧化氢(H2O2)含量、丙二醛(MDA)含量、超氧化物歧化酶(SOD)活性、过氧化物酶(POD)活性、过氧化氢酶(CAT)活性和游离脯氨酸(Pro)含量等生理指标的影响.结果表明,在低N、P胁迫条件下,作为坛紫菜品质重要指标的光合色素、粗蛋白和游离氨基酸含量均显著下降,而其余各项生理指标均随胁迫时间增加表现为动态变化的过程,由此推测耐低N、P型坛紫菜叶状体应答低N、P胁迫的生理过程为:低N、P胁迫→活性氧含量上升→细胞膜氧化受损,产生大量膜脂过氧化物→细胞感受到过量的活性氧信号→抗氧化系统和渗透压调节系统共同响应,清除活性氧→自由基含量下降.该实验结果为全面了解坛紫菜应答低N、P胁迫的生理机制奠定了基础,同时也为后续坛紫菜抗逆新品种的选育提供了理论指导.
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