不同生长阶段的坛紫菜对琼胶寡糖激发的响应差异研究

Study on the different responses of different growth stages of Pyropia haitanensis to agaro-oligosaccharides

为研究不同生长阶段的坛紫菜对琼胶寡糖激发子的抗性响应差异,选择生长期为50、60、80、110和140 d的坛紫菜叶状体以及自由丝状体,检测在琼胶寡糖刺激后各生长阶段坛紫菜的H_2O_2释放,相关防御基因(Phhsp70、Phrboh、Phsod、Phlox)的表达,以及挥发性物质的变化。结果显示,丝状体H_2O_2的释放量显著高于叶状体,100μg/m L琼胶寡糖可诱导不同时期坛紫菜的H_2O_2爆发。丝状体响应琼胶寡糖刺激后,4个防御相关基因出现显著上调,而叶状体各生长阶段的基因上调幅度较小,各基因变化趋势不同。挥发性物质的种类及含量在不同生长阶段不同,但C8类物质较多。经寡糖处理后,80 d叶状体和丝状体时期的挥发性物质增加的种类较多。研究表明,不同生长阶段的坛紫菜对琼胶寡糖刺激的响应能力和方式不同,以丝状体的响应最强烈。

Oligosaccharides could induce physiological responses of algae to defend attacks from pathogens. This study was designed to research the different responses of different growth stages of Pyropia haitanensis to agaro- oligosaccharide elicitor. Six growth stages including 50, 60, 80, 110 and 140 days P. haitanensis thallus and free- living conchocelis were selected to detect the release of hydrogen peroxide （H202） by （p-hydroxyphenyl） acetic acid fluorometric method, expression of defense related genes （Phhsp70, Phrboh, Phsod, Phlox） by real-time quantitative RT-PCR, and volatiles changes by GC-MS after being elicited with agaro-oligosaccharides. The results showed that, without treatment with agaro-oligosaccharides, free-living conchocelis contains significantly higher levels of hydrogen peroxide and fatty-derived oligosaccharides can induce the quick outbreak of H202 volatiles than those of the thallus. 100 μg/mL agaro- of different growth stages ofP. haitanensis, and thallus responded faster than conchocelis. Four defense-related genes were significantly up-regulated in conchocelis, such as Phlox was up-regulated 166.06±56.52 folds, while the genes of thallus at different growth stages exhibited a slight extent of up-regulation, moreover, the changes of these genes had variation trend at different stages. The composition and contents of volatile substances varied with different growth stages, but the 8-carbon volatiles predominated, such as 2-octenal, 5-octen-l-ol, 2-octen-l-ol and 1-octen-3-ol, etc. By using PCA method, the profiles of volatiles of thallus and conchocelis could be separated clearly, indicating an obvious difference in the profiles of volatiles between them. After being stimulated with agaro-oligosaccharides, some new volatiles in 80 d thallus and conchocelis were generated, and some 8-carbon volatiles were increased significantly. Overall, these results indicated that the different growth stages of P. haitanensis had different response modes to agaro- oligosaccharides, in which conchocelis responded most intensively.