Genomic Analysis And Metabolic Response Of Pigments And Lipids Under Different Photoplasm Of Chaetoceros Muellerii

Chaetoceros mulleri is a marine diatom with short growth cycle and strong environmental adaptability.Fucoxanthin(Fx)is a characteristic pigment of diatoms,which has good physiological functions.At present,its biosynthetic pathway is not clear.In this paper,based on the genome and transcriptome sequencing of C.mulleri,we studied the difference of Fx and lipid induction of C.mulleri with different light quality,in order to artificially regulate and improve the synthetic efficiency of the product in C.mulleri.The main research contents and results of this paper are as follows:Identification and analysis of Fx and oil of C.mulleri.Purification and morphological identification of Chaetocerata preserved in laboratory.The genome of C.mulleri was extracted and used as a template for 18 S r DNA sequence amplification,identification and clustering.Combined with the morphological information under various microscopes,the alga was identified as C.mulleri.Flow cytometry estimated the genome size of the alga to be about 55.4M.At the 8th day of culture,green,red,white and blue light treatment group per litre algae fluid Fx content were 32.37 mg,33.77 mg,27.37 mg,17.25 mg,the white,red,blue,green treatment group per litre algae fluid containing oil were 16.96 mg,16.11 mg,15.8mg,15.21 mg,DHA,EPA cumulant relationship is: Blue>White>Green>Red.C.mulleri genome sequencing and assembly using the Illumina sequencing platform sequencing and about 9.5Gb of data quality after filtration,genome coverage of about 265×.K-mer method to estimate C.mulleri genome size is about 33.9 to37.6Mb,heterozygosity is 1.04-1.1%.Using Pac Bio Sequel gained 10.1 Gb DNA sequencing data of C.mulleri,coverage of about 302×.The total length of the genome was 35.8Mb,the scaffold N50 was 1,238 kb,and the GC content was 41.34%.C.mulleri genome annotation using marker process for gene prediction and RNA structure prediction,a total of 10055 protein-coding genes,gene encoding length of about 1,937 bp on average,gene accumulative total length of 19,474,704 bp,accounting for 54.39% of the whole genome.C.mulleri genome data in NR,Swiss-Prot,GO,egg NOG and KEGG database have commented on the number of genes is 1542,accounting for 15.34% of the total number of protein-coding genes.The number of genes with at least one database annotation is 7906,accounting for78.63% of the total number of protein-coding genes.Through Repeat Master annotation,a total of 18503 scattered repeats and 6358 tandem repeats were obtained.In addition,84 t RNAs,42 r RNAs and 2 sn RNAs were also observed.Seventeen transcription factor families including HSF heat shock protein families,C2H2,b ZIP,C3 H,MYB et.al were identified in the nuclear genome of C.mulleri.C.mulleri chloroplast(cp)genome assembly comments get size of 116,415 bp does not contain introns,round double-stranded DNA molecule structure,containing a size of 61,902 bp of LSC,39,361 bp of SSC and two identical IRs of size 7,576 bp.The chloroplast genome contains 30 t RNA,66 CDS,16 r RNA.The key enzyme of carbon metabolism,the large and small subunit of ribulose bisphosphate carboxylase,are annotated in the cp genome.The essential enzymes of C3,C4,and CAM metabolism are in the genome of C.mulleri.However,the mechanism of carbon metabolizes remains unknown.It contains transporter of nitrate,ammonium,urea and amino acid,but lacks of transporter of nitrite,polyamine,oligopeptide,balanced nucleoside and cyanate lyase.The algae did not annotate LPP,but could annotate high affinity phosphate transporter,low affinity phosphate transporter,sodium dependent phosphate transporter,inorganic phosphate transporter and other proteins needed for phosphorus metabolism,so it could utilize inorganic phosphorus and organic phosphorus.The results show that the most enzymes in the metabolism of Fx in the hypothesis can be annotated by C.mulleri,extremely for neoxanthine synthase(NXS,which has not been reported in other diatoms),not for ?-carotene hydroxylase.Transcriptome analysis of C.mulleri under different light quality conditions.RNA-Seq sequencing of C.mulleri under different light quality conditions was carried out by Illumina Hiseq technology.Based on TPM method,16 modules were obtained by analyzing the expression of metabolic genes in white,red,blue and green light quality.Three modules were identified to be highly related to lipid and pigment metabolism,involving 605 candidate genes.The hub gene in the module was annotated and two transcription factors were found to belong to the HSF heat shock protein family.In this study,we analyzed the nuclear and chloroplast genomes of Chaetoceros muelleri,analyzed the pathways of carbon fixation,nitrogen metabolism and phosphorus metabolism,and provided basic data for the subsequent transformation of C.mulleri and the exploration of diatom evolution.Light quality transcriptome analysis revealed the expression regulatory network of some genes related to fucoidin biosynthesis pathway,which laid a foundation for understanding the fucoidin biosynthesis pathway and its regulatory mechanism.