Preliminary Analysis Of The Mechanism About UV-B Absorbing Compounds Of Pyropia Haitanensis Under Adversity Stress

Pyropia haitanensis is an important economic macroalgae at the southern coast of China.Recently,the aquaculture of P.haitanensis facing serious problems,such as,deteriorated germplasms and high temperature induced thallus decomposition.Thus,study the mechanisms of stress tolerance of P.haitanensis could promote the breeding of new varieties with advantageous traits.In this study,wild strain and high temperature resistant strain Z-61 of P.haitanensis were selected as materials.Firstly,the contents of UV-B absorbing compounds were investiaged under different stressors(high temperature,water loss and highlights);Second,full length sequences of genes involved in the synthesis of UV-B absorbing compounds have been cloned;Third,deep analysis were performed to analyzed gene expression under different stresses and between different phases of life cycle.This study was to provide the basic materials for the researches of breeding and genetic engineering of P.haitanensis.The main results are as follows:1.Contents of UV-B absorbing compounds responsed differently to 3 stressors,high temperature,dehydration and high light;the contents of phycocyanin did not significantly change by high temperature and dehydration stressors,but decreased significantly by high light,while as MAAs,one kind of UV-B absorbing compounds,significantly increased by various stressors.Furthermore,different stages of life cycle exhibit significant difference on the contents of phycocyanin and MAAs,higher in thallus relative to that of conchocelis.2.PCR and RACE amplification methods were conducted in present study,two enzyme genes involved in synthetize MAAs were cloned and named PharoB-1 and PharoB-2.PharoB-1 gene contains two encoding structure domains,aroB and o-mt;Besides,two genes encoding the enzymes of agar synthesis had been cloned,named as Phglugp and Phgalt.3.The gene expression levels under high temperature,dehydration and high light stressors were analyzed using real-time quantification PCR technology.Genes related to MAAs synthesis were upregulated under high temperature,dehydration and high light conditions;As for genes related with agar synthesis,the expressions were raised by high temperature and dehydration,but down-regulated by high light.These results suggested that different stressors have specific pathways to influence primary metabolic targets of P.haitanensis,such as,UV-B absorbing compounds,agar,phycocyanin,etc.In addition,the gene expression levels of UV-B absorting compounds synthesis were consistent with physiological performance.That maybe relate to the different habitats and merabolism situations of life phases of P.haitanensis...