The Changes Of Floridoside Content And The Expression Of Stress Resistance Related Genes In Pyropia Haitanensis(Rhodophyta) Under Heat Stress

A facile method based on liquid chromatography coupled with triple quadrupole mass spectrometry has beenestablished to analyze floridoside and isofloridoside in the red algae. Correlation coefficients of the calibrationcurves were lager than0.9993, indicated good linearity. The detection limits and of floridoside and isofloridosidewere0.05and0.20ng/mL, respectively. The quantification limits floridoside and isofloridoside were0.10and0.40ng/mL, respectively. The recoveries varied from75.7%to76.8%. And the relative standard deviations ofinter-day and intra-day precision were lower than8.5%(n=5).Floridoside and isofloridoside contents in the seven red algae (Gloiopeltis furcata (Postels&Ruprecht) J.Agardh, Pyropia haitanensis, Caulacanthus okamurai Yamada, Gelidium divarica-tum Martens,Gymnogongrus flabelliformis Harvey, Grateloupia filicina (J.V. Lamouroux) C. Agardh and Champiaparvula (C. Agardh) Harvey) which were inhabited in the different tidal level in intertidal zone were investigatedby this method. It was showed that the contents of floridoside related to tidal level. The lower the inhabit level inintertidal zone was, the less contents of floridoside the algae had, while the isofloridoside could be found only inGloiopeltis furcata (Postels&Ruprecht) J. Agardh and Pyropia haitanensis.The results of floridoside and isofloridoside contents in Pyropia haitanensis showed that the floridosidecontent of the same cultivar was about0.61-0.66mg/g, which was relatively stable and has no relationship with thecultivated field (P>0.05); however the isofloridoside content was ranged from6.14mg/g to7.31mg/g, which wassignificantly different from the culture location(P<0.05). The floridoside contents were declined from the group I(conchocelis), the group II (thalli of45days), the group III (thalli of75days) to the group IV (thalli of135days).The contents of floridoside in the conchocelis and the young group were great significantly higher than those ofthe latter two stages (P<0.01). But the highest isofloridoside content was observed in group II.The thalli of P. haitanensis were heat-schocked at35℃for30min. The contents of floridoside andisofloridoside of thalli were observed right after heat shock, and recovered in the normal cultivation temperaturefor1h and3h. The results showed that the content of floridoside was decreased under heat shock and thengradually picked up to nearly two times compared with the control group when it was released from the heatshock(P<0.01). The changes of isofloridoside contents were unsignificant during this process (P>0.05). Thechange capacity of floridoside content of different growth stages were decreased significantly from group III、group IV、group II to group I (P<0.01). And the change capacity of floridoside content of high temperatureresistant cultivars ShenFu NO.1(V group,45day) were significantly higher than that of Me-05cultivars (groupII)after heat shock (P<0.05). The changes of isofloridoside contents were not significant in these groups (P>0.05).The expression of the stress resistance related genes were detected by realtime-quantitative polymerase chainreaction (RT-qPCR). After heat-schocked, the expression of the genes (Phnhol and Phgpdh) which related to themetabolism of floridoside were increased significantly, which consistented with the changes of floridosidecontents in the recovery process. And the expression of molecular chaperones (hsp70)and free radical scavengingenzyme genes(Mn-sod, rboh) were also significantly increased. The results suggest that: The floridoside content of the same cultivar is relatively stable and has norelationship with the cultivated field. The floridoside as a kind of osmolyte and active oxygen scavenging systeminvolved in the process of heat shock and the restore metabolism. The content and regulation capability offloridoside may lead to different heat resistance in seaweed, the higher the content and change ability is, the betterresistance is. The role of isofloridoside is still unclear which needing further study.