| Gracilariopsis lemaneiformis is a new large-scale cultivation of seaweed after Laminariajaponica，Porphyra yezoensis and Undaria pinnatifida. Because of its rich nutritional value andpotential economic value, in recent years it has been praised by the favour. In the paper, the hightemperature resistant varieties of981Gracilariopsis lemaneiformis were used as materials to studyon the effects of different concentration of salicylic acid on their growth under stress temperature.The antioxidant enzyme activity and MDA content, the osmotic regulation substances，phycobiliprotein，the features of chlorophyll fluorescence and HSP70gene were studied when thealgae grew under high temperature environment. To study the algae body’s physiological responsemechanism of Gracilariopsi lemaneiformis and the salicylic acid’s application prospect in thealgae breeding process under high temperature conditions.In this experiment, the variety of981Gracilariopsis lemaneiformis was used as material, set6concentration group of salicylic acid treatments that0，2.5，5.0，10.0，20.0and50.0μg/mL. Tocultivate the Gracilariopsis lemaneiformis under the normal temperature25℃and hightemperature33℃environment. Results show that exogenous salicylic acid can improve the growthrate of Gracilariopsis lemaneiformis under normal temperature.10.0μg/mL treatment group’sdaily relative growth rate increased26.3%more than the control group, and it can promote theaccumulation of mannitol and proline after salicylic acid treatment. The treatment group with10.0μg/mL had the best effects. The treatment improved SOD、POD enzyme activity and reduced theaccumulation of MDA. It also promoted the accumulation of Ca2+and K+ions in the algae’s bodyof Gracilariopsis lemaneiformis, increased the proportion of phycobiliprotein and enhanced thevarious index of chlorophyll fluorescence parameters, ΦPSⅡ index begin to increase in the fifthday after treatment. It increased9.6%compared with control group. Photochemical conversionefficiency Fv/Fo reached a maximum in the fifth day. It increased5.6%more than the controlgroup. The treatment group with salicylic acid added, their growth，enzymatic activity or membranelipids damage are better than those control group in a various degree under high temperatureenvironment, among which the treatment groups of5.0and10.0μg/mL of salicylic acid wereobviously better than the other treatment groups. And the treatment group of10.0μg/mL ofsalicylic acid showed the most obvious effect, the daily growth rate increased340%compared withthe control group. When the treatment was at the3rd days, each index of the treatment group of10.0μg/mL reached maximum value. The results showed that the Gracilariopsis lemaneiformis ‘schlorophyll fluorescence parameters Fv/Fm、ΦPSⅡ、qP and Fv/F0obviously decreased underhigh temperature stress. qP and ΦPSⅡ r eached the maximum after the treatment of adding10.0ug/ml salicylic acid, improved7.5%and25.7%more than the control group respectively.Moreover, the variation tendency of NPQ increased firstly and then declined with the hightemperature stress. Both the control group and treatment group achieved maximum at the sametime in the fifth day. The treatment group of salicylic acid improved22.5%more than the blankcontrol group.In this paper, the (HSP70) genes and PE genes of Gracilariopsis lemaneiformis were clonedto study the influence of the treatment of salicylic acid on the gene’s expression level. The resultsshowed that whether with the normal or high temperature’s treatment, the concentraton10.0μg/mlHSP70mRNA expression were obviously lower than other treatment groups（P<0.05）, only are40%and31.6%of the expression of the control group. Through the study of the phycoerythringenes of Gracilariopsis lemaneiformis, we found that adding salicylic acid had no positive effectson phycoerythrin, only when the treatment group with the low concentration2.5μg/ml,theexpression of the treatment group was higher than the control group. But under high temperaturestress,10.0，20.0，50.0μg/ml had the most obvious influence on the expression of thephycoerythrin genes. Among which the concentration group of10.0μg/ml had increased six timescompared with the control group. |
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