Comparative Quantitative Proteomic Studies Of Pyropia Haitanensis In Response To High Temperature Stress

Pyropia haitanensis is one of the most economically important mariculture crops in south China.In recent years,high temperatures associated with global warming,have markedly affected the cultivation of P.haitanensis and reduced its yield and quality.In order to keep normal development of P.haitanensis cultivation,several new strains of P.haitanensis exhibiting high temperature tolerance and high growth rates have been selected.These strains have been widely cultivated in South China,and their traits of high temperature tolerance have been validated by field cultivation.To understand the mechanism of high temperature tolerance,the technologies of chlorophyll fluorescence measurement and iTRAQ of proteomics were used to analyze the photosynthesis and expression patterns of proteins in a high-temperature tolerant strain of P.haitanensis,and the main results are as follows:1.The modulated chlorophyll fluorometer（DIVING PAM）was used to measure the photosynthesis efficiency of P.haitanensis thallus under different dark-adaption time,different light intensity and different time interval of photosynthetic induction curve.The results showed that the photosynthetic values were best performance when the parameters were setting as:dark-adaptation time is 15 min,PAR is 100μmol·m^-2·s^-1 and time interval is 30 s.The results also showed that the photosynthesis efficiency is the most stable between 10:30 and 16:30 in daytime,so this period is the appropriate time to measure photosynthesis efficiency.2.DIVING PAM were used to compare the photosynthetic efficiency of a high temperature–tolerance strain Z-61 and a wild-type strain under 29℃with different time points（0 h,3 h,6 h,12 h and 24 h,48 h,96 h,144 h）.The results show that the photosynthesis efficiency of Z-61downregulated more slowly and much less than the wild-type strain under high temperature stress;the ability of photoprotection of Z-61 also can recover to the normal level after the long times high temperature stress,but the wild-type strain can not recover;and the time limit of high temperature tolerance of Z-61 was 48 h,but the wild-type strain was 24 h.These results suggested that Z-61 strain have more stronger high temperature tolerance than the wild-type strain.3.iTRAQ technology was used to compare the proteomics of Z-61 under different times（0h,3 h,6 h,12 h,24 h,48 h,96 h,144 h）of high temperature stress,and 283 differentially expressed proteins were found.The result of functional categories showed that the Z-61 strain can accumulate chaperone proteins and antioxidant proteins to reduce the damage of high temperature stress,and resist high temperature stress by inhibiting photosynthesis and other nonessential metabolic processes,thereby maintaining physiological balance during stress.4.The results of chlorophyll fluorescence measurement and iTRAQ of proteomics showed that the Z-61 strain has more power ability to response to high temperature strss by accumulating chaperone proteins and antioxidant proteins which can keep the physiological balance of cell.