多形微眼藻在不同氮源条件下固碳途径的转录组解析及与其他微藻的比对

TRANSCRIPTOME ANALYSIS OF CARBON FIXATION PATHWAY OF MINUTOCELLUS POLYMORPHUS UNDER DIFFERENT NITROGEN SOURCE CONDITIONS AND THE COMPARISON WITH OTHER MICROALGAE

本研究通过转录组技术对不同氮源培养下的多形微眼藻(Minutocellus polymorphus)固碳途径进行分析。通过对转录本进行NR、NT、Swiss-Prot和KOG富集分类及GO、KEGG相关代谢途径和基因差异表达分析,构建了多形微眼藻固碳途径。研究发现该藻除具有C3固碳途径外,还具有较完整的C4固碳通路。在注释到的164个固碳相关编码基因中,有33个出现明显表达差异。根据基因的差异表达情况可以发现,在有机氮源中多形微眼藻C3固碳途径的核酮糖-1,5-二磷酸再生阶段和C4固碳途径的磷酸烯醇式丙酮酸再生阶段相关编码基因均有上调表达,C4固碳羧化阶段相关编码基因均有下调表达。研究对比了多形微眼藻与假微型海链藻(Thalassiosira pseudonana)、三角褐脂藻(Phaeodactylum tricornutum)和抑食金球藻(Aureococcus anophagefferens)固碳途径的异同点,发现多形微眼藻与抑食金球藻有相似的C4固碳途径,与三角褐脂藻有相似的C3固碳途径。进一步分析多形微眼藻碳氮代谢途径基因表达情况,发现两种代谢途径相互支撑,存在协同效应。研究结果可丰富微藻的固碳通路研究,也可为深入分析褐潮暴发原因提供依据。

The carbon assimilation pathways of Minutocellus polymorphus cultivated with different nitrogen sources were analyzed by RNA-seq.The transcripts were classified by NR,NT,Swiss-Prot and KOG enrichment and analyzed by GO,KEGG metabolic pathways and gene differential expression,through which the carbon assimilation pathways of M.polymorphus were constructed.It was found that there was a complete C4 carbon assimilation pathway in addition to the C3 pathway in M.polymorphus.Of the 164 carbon-fixing genes noted in the pathways,33 genes showed significantly different expression.The coding genes of M.polymorphus in the ribulose-1,5-diphosphate regeneration phase of C3 and the phosphoenolpyruvate regeneration phase of C4 carbon assimilation pathways were up-regulated,and the genes encoding carboxylation in C4 pathway were down-regulated in organic nitrogen cultivation.Moreover,it was compared for the similarities and differences of carbon assimilation pathways among M.polymorphus,Thalassiosira pseudonana,Phaeodactylum tricornutum and Aureococcus anophagefferens.It was found that there was a similar C4 carbon assimilation pathway between A.anophagefferens and M.Polymorphus,and a similar C3 carbon assimilation pathway between P.tricornutum and M.polymorphus.By analyzing the gene expressions of carbon and nitrogen assimilation pathways,it was indicated that these two metabolism pathways supported each other and there was a cooperative effect between them.The results can enrich the study of carbon assimilation pathways in microalgae and provide more information for analyzing the causes of brown tide outbreak.