Transcriptome Analysis Of Different Development Stages Of Pyropia Haitanensis

Pyropia haitanensis is an economically important marine crop in southern China.The algal P.haitanensis genome is small,the number of chromosomes is small,and the generation cycle is short,the entire life cycle can be completed under laboratory conditions and is a good material for genomics,molecular biology and genetic studies.Although many domestic and foreign laboratories have carried out relevant research on the growth and development of P.haitanensis,there is still a lack of systematic analysis of the whole growth and development of P.haitanensis.In this experiment,samples from different developmental stages of the wild pyropia strains "Beilanling",which preserved in the Lab of P.haitanensis of Jimei University were used as experimental materials.By analyzing the changes of transcriptome and expression profiles and physiological and biochemical indicators,the regulatory mechanism of P.haitanensis in its growth and development was explored.The main results are as follows:1.High-throughput sequencing was used to analyze the global transcriptome of P.haitanensis.Approximately 729 million 125 bp paired-end reads were generated using an Illumina HiSeq 2500.De novo assembly with paired-end information yielded 42,138 unigenes with an average length of 819 bp.Based on sequence similarity searches with known proteins,a total of 25,362(60.19%)genes were identified.2.Through the transcriptome sequencing analysis of 16 samples of P.haitanensis at different developmental stages,the molecular mechanism of different growth stages of P.haitanensis was preliminarily elucidated:①The process of Filamentous Algae form Double Spore,the phosphatidylinositol signaling system-related genes were significantly up-regulated,indicating that the phosphatidylinositol signaling system may be involved in the signal transduction process of algae during changes in the ambient temperature.Photosynthesis,antenna protein,cytochrome C,and phycobiliprotein all showed a trend of rising first and then decreasing,and the apparent synaptic rate of Double Spore was also significantly lower than that of Filamentous Algae,explain that a large amount of photosynthesis is needed during the formation of bisected spores to accumulate more substances for the differentiation of bisected spores and to prepare for the release of shell spores.②The process of the Double Spore release Conchospore and the Conchospore becoming the Thallus,meiosis occurs when Conchospore was divided into four,genes related to DNA repair in the stage of meiosis were significantly up-regulated during the Conchospore,demonstrate that the Conchospore may need to undergo a large number of folding repairs in the process of chromosome halving to ensure the smooth halving of chromosomes.The single cells of Conchospore need to deal with complex water environments,in this process,the proline synthase gene and ubiquitin-conjugating enzyme gene were significantly up-regulated during the period of Conchospore,it means that these genes play an important role in adaptation to the aquatic environment after the release of Conchospore.③The process of Thallus cells into germ cells and formation of zygote,genes related to DNA replication and Histone are significantly up-regulated at the germinal stage,and Actin and Tubulin genes shows the same trend,explain that these genes regulate DNA replication and chromatin remodeling during germ cell formation.In addition,Photosynthesis,Nitrogen metabolism,Carbon metabolism,Starch and Sucrose metabolism,Glycolysis,and Pentose Phosphate pathway related genes were down-regulated at the germinal stage.And the Antherid have a significantly lower level of apparent photosynthetic rate than the period of Thallus.It explanation that the Thallus by reducing photosynthetic and basal metabolic levels to reduce energy consumption during cell differentiation.In addition,the agar content of the Thallus was significantly higher than that of the Filamentous Algae,and the expression of genes associated with the agar synthesis of the Thallus was significantly higher than that of Filamentous Algae,indicating that the Thallus could utilize more galactose to synthesize agar is used for the formation of the cell wall of the P.haitanensis.④The process of Carpospores form Filamentous Algae,in this process,genes related to macromolecular HSPs,Auxin signal transduction,and Jasmonic acid signal transduction were up-regulated significantly,and the Photosynthetic genes shows the same trend.This shows that these genes play an important role in the morphogenesis of new Filamentous Algae and in improving the adaptability of fruit spores to the water environment.However,more conclusions need further experimental verification.