Study On Genetic Breeding And Functional Gene In Bangiaceae

Seaweed,which has high nutritional value,has been widely applied in biopharmaceutics,industry and other fields,and the market demand for seaweed is increasing.It has led to the growing scale of aquaculture and the continuous optimization of breeding technology in China.In this study,we explored genetic background and physiological response mechanism under stress resistance by molecular cloning,marker and low salt stress using Pyropia yezoensis and Bangia as experimental material.It aims at enriching the germplasm resources of the northern seaweed and reducing the risk of seaweed aquaculture.New strain of “Huangyou No.1”,obained by selective breeding of the wild germplasm from the farming ropes of Tuoji Island,were cultivated in Nantong,Rizhao and Tuoji Island,respectively.The biochemical components(phycobiliprotein,chlorophyll a,carotenoid and soluble protein)were analyzed in “Huangyou No.1” from different farming areas together with its parent,the control strain of Pyropia yezoensis in Rizhao,the wild Pyropia from the shore of Tuoji Island and its cultivated offsprings.The results of the biochemical content of “Huangyou No.1” cultivated in the Rizhao was generally higher than the other cultivars and their wild germplasm,and the quality of seaweed cultivated in the Nantong was the lowest.The results show that the biochemical compositions of the “Huangyou No.1” in different sea areas were superior to that of its wild parents and “Huangyou No.1” is more applicable for cultivation in the sea area of Rizhao.Based on the sequence of rbc L gene(about 1200 bp),there were about 1.1%variation occurring in the population of the wild Pyropia growing on farming rope,compared to the other populations,and all the other 6 populations had completely same rbc L gene sequence.According to genetic diversity analysis of CO ? gene sequence(about 680 bp),only two cultivars(“Huang You 1”and Breeding 2)of Nantong had 2 bp difference,and the others were completely consistent.And according the AFLP result,totally,249 loci were obtained,of which 248 were polymorphic with a polymorphism rate of 99.6%,using seven primer pairs.The intra-population polymorphism rates ofpopulations Wild 1 and Wild 2 were the highest(47.39% and 59.44%,respectively),while they were relatively low(20.88–24.5%)in the cultivated populations.The genetic distances between the breeding Pyropia populations cultivated in the same aquaculture farm were low.Specifically,the F2 offspring of “Huangyou No.1” and control cultivar,cultivated using the “never-drying” protocol,were genetically distant from the other populations,including that from the same seedlings,yet cultivated using the“periodic-drying” protocol.The never-drying cultivation protocol had a high likelihood of influencing genetic diversity of Pyropia yezoensis.The PM H+-ATPase gene PMHA1 was cloned with RACE PCR.After sequences fragment assembly,the full c DNA of PMHA1 gene was obtained,the length of which was 3368 bp.It contained an open reading frame(ORF)of 3129 bp,encoding a1042-amino-acid polypeptide with a molecular weight of 106.51 k D and flanked by 131 bp on its 5' untranslated regions(UTR)and 108 bp on its 3' UTR.There were 77 phosphorylation sites at the PM H+-ATPase of Bangia with complex distribution.It was speculated that more phosphorylation sites could more rapidly prompt enzyme activity to adapt to external stress,which has a high sensitivity.The cluster analysis of Bangia and the other 13 plant species based on the PM H+-ATPase gene showed that there was a certain similarity among the fourteen species,but the diversity was also significant.In order to further research the function of PM H+-ATPase of marine plant in the stress response mechanism,the relative expression of the PM H+-ATPase gene PMHA1 of Bangia under different degrees of low salt stress was detected by q RT-PCR in this research.The result showed that the expression increased with the reduction of sea water,and increased first and then decreased with same treatment time.According to the results,in order to resist the environmental stress,the PMHA1 gene expression of Bangia could be up-regulated to maintain the chemical potential gradient inside and outside the cell,which make the algae to adapt to adversity as soon as possible.However,the physiological response mechanism will be damaged and unable to continue self-regulation beyond the ability to resist stress.