Transcriptome Analysis Of Fucoxanthin And Fatty Acid Synthesis Induced By Blue Light In Isochrysis Globosa

Isochrysis galbana is a marine microalgae with a short growth cycle and no cell wall.It is rich in fucoxanthin and a variety of unsaturated fatty acids.It is a rare and valuable algae resource and is widely used in medical and health care.Energy production,aquaculture and other fields.Fucoxanthin has antioxidant capacity;DHA,also known as "brain gold",promotes brain development,has anti-cancer,prevent cardiovascular diseases and other functions.By studying the effects of different light quality cultures on Isochrysis fucoxanthin and fatty acid content,blue light-induced Isochrysis fucoxanthin and fatty acid synthesis transcriptome and the gene family of key regulatory factors in the synthesis of active substances,we can further Improve the application value of algae strains and contribute to industrialization.The main research contents and results of this paper are as follows:1.Explore the effects of different light quality(white light,green light,blue light,blue light plus green light)and different time(3,5,7,9 days)cultivation on the growth of Isochrysis galbana,fucoxanthin and fatty acid content.Compared with white light conditions,the cell density of the green light group was higher in the first 3 days;the growth status of the blue light group was almost the same as that of the white light group;the growth status of blue-green mixed light was not as good as that of the white light group,that is,short-term green light stimulation was beneficial to the growth of algae cells.Blue and green mixed light will inhibit the growth of algae cells.After green light treatment,the fucoxanthin content in the system,unit dry weight,and unit cell was significantly higher than that of the white light group;after blue light treatment,the fucoxanthin content was lower than that of the white light group;after blue-green mixed light treatment later,the content of fucoxanthin was higher than that of the white light group,that is,green light and blue-green mixed light were beneficial to the accumulation of fucoxanthin content,while blue light inhibited the accumulation of fucoxanthin.Through the study of different light quality on the fatty acid metabolism accumulation of Isochrysis galbana,it was found that the fatty acid content of the green light culture to the 5th day was significantly higher than that of the white light group.Taken together,green light significantly promotes the accumulation of isochrysis fucoxanthin and fatty acids.2.Exploring the transcriptome of blue light-induced Isochrysis galbana to synthesize fucoxanthin and fatty acids.After RNA is extracted from the sample,it is sequenced based on the Illumina platform.The number of genes expressed in 24 samples totaled 290,257,and the number of expressed genes was more than 11,000.The difference analysis between the white light group and the blue light group on the 9th day showed that 641 genes were effectively differentially expressed,of which 320 were up-regulated and 321 were down-regulated.KEGG enrichment was performed on the differential genes between the white light group and the blue light group on the 9th day.The genes annotated to predict the down-regulation of the unsaturated fatty acid metabolic pathway are FAD2,HADD,SCD,HSD17B4,HSD17B12;the genes that are annotated to the carotenoid metabolic pathway are predicted to be down-regulated Genes include Crt B,PDS,Z-ISO,ZDS,LCYB,ZEP,VDE,combined with differentially expressed genes,we predicted the key regulatory genes of fucoxanthin and fatty acid synthesis pathway.At the same time,the content of fucoxanthin and fatty acid in a single cell was lower than that of the control group,further indicating that blue light induction would inhibit the accumulation of fucoxanthin and fatty acid content.Through WGCNA analysis,the gene modules related to Fucoxanthin,lipid,and DHA were determined.At the same time,the core gene interaction network was visualized and the core genes involved in the regulation of fucoxanthin and fatty acid synthesis were predicted.Differentially expressed genes(IZ002759,IZ014151,IZ001838)were selected for fluorescence quantitative PCR verification,and the results were consistent with the predictions.3.Using the genomic data of Isochrysis galbana constructed by our laboratory,60 MYB gene family members,22 FAD gene family members,12 were screened and identified through the hummer program and the Pfam database(Pfam numbers PF00249,PF00487,PF00067)A member of the CYPs gene family.The physicochemical properties,secondary and tertiary structures,transmembrane domains,signal peptides,subcellular structure localization,chromosomal localization and collinearity of the proteins encoded by these genomic group members were analyzed,and it was found that their physical and chemical properties were quite different.Most of the MYB gene family members are unstable hydrophilic proteins,of which only IZ001203 and IZ003517 are transmembrane proteins,while the FAD and CYPs gene family members are mostly stable hydrophilic proteins;the MYB gene family members are distributed on 9 chromosomes.The two genes IZ004469 and IZ004470 are adjacent to each other on the chromosome,forming obvious gene clusters.FAD and CYPs gene family members are distributed on 9 and 6chromosomes,respectively.The secondary structure is mainly composed of ?-helix,extended chain and random coil structure.According to the homology of protein amino acid sequence,the phylogenetic tree of Isochrysis galbana,Chlamydomonas reinhardtii and Phaeodactylum tricornutum was constructed,and the members of Isochrysis galbana MYB,FAD and CYPs gene family were classified.The cis-acting elements in the promoters of Isochrysis galbana MYB,FAD,and CYPs gene families have the most light response elements,and there are also many response elements related to plant growth hormone and abiotic stress response elements.