Primary Study On Osmoregulatory System Of Pyropia Haitanensis Under High Temperature And Dehydration Stress

Pyropia haitanensis is an important economic macroalgae in southern coast of China.In recent years,rotten germlings caused by the high temperature and the germplasm degeneration have become major problems for cultivation of P.haitanensis.Therefore,it’s very important to study the response mechanisms of P.haitanensis to abiotic stresses and breed new varieties.Choosing the Z-61 strain as materials,this study cloned the whole sequence of genes encoding the enzymes related with osmotic adjustment,analysed the effect of osmoregulatory system response to high temperature and dehydration stress by gene expression and metabolome methods to provide theoretical basis for breeding new varieties and genetic engineering of P.haitanensis.The main results are as follows:1.Gas chromatography/mass spectrometry technique was used to analyse the metabolome of P.haitanensis under high temperature and dehydration stress.The results showed that metabolites in cells changed differently with the high temperature stress and dehydration stress.the contents of amino acids such as proline,asparagine and serine accumulated,sugars such as trehalose and D-arabitol,polyols such as glycerol were significantly increased under abiotic stresses.2.The contents of proline,glycerol and trehalose under high temperature and dehydration stresses were measured by using gas chromatography technology.The results showed that three substances were significantly increased under abiotic stresses.It can deduced that the proline,glycerol and trehalose are important osmotic matters of P.haitanensis.3.Seven genes encoding the enzymes related with osmotic adjustment were cloned by using the rapid amplification of cDNA ends(RACE)technology or direct PCR.They were named PhTPS1,PhTPS2-1,PhTPS2-2,PhGPDH1,PhGPDH2,PhOAT and PhCDH.The full-length cDNAs of the 10 genes comprised 3616,4264,3733,1496,1953,2011 and 1936 nucleotides.And the cDNAs encoded proteins of 1153,1347,1107,386,510,498 and 613 amino acids.4.The expression pattern of each gene under high temperature(29 ℃)and dehydration stress was analysed by using real-time quantification PCR technology.It showed that most genes upregulated under dehydration stress,but they did not actively response to high temperature stress.These results suggest that osmoregulatory system of P.haitanensis must play important roles in dehydration tolerance.5.The contents of proline,glycerol and trehalose under high temperature and dehydration stresses are in accordance with the expression patterns of genes.Thus,it can deduced that the cloned genes have a connection with the osmoregulatory system of P.haitanensis,participated in the synthesis of osmotic matters.These results present new genes which have important functions in abiotic stress and will create a foundation for a breeding profile for P.haitanensis in relation to stress tolerance.