磷镉交互作用对普通小球藻(Chlorella vulgaris)的毒性效应

Toxic Effect of Phosphate and Cadmium Interaction on Chlorella vulgaris

外源磷供应能够显著影响痕量元素对微藻的毒性作用,提高磷浓度能够降低金属元素对藻类的毒性。为研究磷镉交互作用对普通小球藻(Chlorella vulgaris)的毒性作用。本研究以小球藻K-01为研究对象,分别对低磷(LP)、中磷(MP)和高磷(HP) 3种条件下培养的小球藻做镉胁迫(10 mg/L Cd^(2+))和正常条件(0 mg/L Cd^(2+))处理。结果表明,经过镉处理的小球藻其生物量、叶绿素含量较正常组均显著下降,且随着磷浓度的增高,下降的趋势减弱。镉处理组中小球藻的相对脂含量增加,随着磷浓度的增加,相对脂含量不断上升。在此基础上选择低磷(LP)和高磷(HP)条件下的培养的小球藻做镉胁迫(10 mg/L Cd^(2+))和正常条件(0 mg/L Cd^(2+))处理,每组3个生物学重复,收集培养4 d后的样品进行转录组测序,以无镉处理为对照,LP培养条件下镉处理组和无镉组差异表达基因有442个,上调的有332个,下调的有120个。HP组中镉处理组和无镉组有效差异表达基因有397个,上调的有235个,下调的有162个。KEGG pathway富集分析各列出20条pathway,这些差异基因富集的通路主要包括脂肪酸合成和不饱和脂肪酸的生物合成、糖异生和糖酵解、光合作用等代谢途径等。同时对转录因子进行功能分析,发现了来自21个家族的177个转录因子,主要包括C3H家族、C2C2和C2H2家族、MYB家族、AP2/ERF家族以及CAMTA家族。本研究对磷镉交互作用对普通小球藻的毒性作用进行分析,并通过转录组发现了与镉胁迫相关的代谢通路及转录因子,为阐明小球藻耐镉机制提供参考。

Exogenous phosphorus supply can significantly affect the toxicity of trace elements to microalgae,and increasing phosphorus concentration can reduce the toxicity of metal elements to algae.In order to study the toxic effect of the interaction of phosphoate and cadmium on Chlorella vulgaris.Chlorella vulgaris K-01 was used as the research object.It was cultured under three phosphorus concentrations,low phosphorus(LP),medium phosphorus(MP)and high phosphorus(HP)conditions.with cadmium stress(10 mg)and normal conditions(0 mg/L Cd^(2+))respectively.Compared with the normal group,the biomass and chlorophyll content of cadmium-treat group decreased significantly,and with the increase of phosphorus concentration,the decreasing trend weakened.The lipid content in Chlorella vulgaris increased under cadmium stress,and with the increase of phosphorus concentration,the lipid content continued to rise.On this basis,Chlorella vulgaris cultivated under LP and HP with and without cadmium stress for 4 days respectively were selected to conduct transcriptome sequencing,each group containing three biological repetitions.Under LP with cadmium treatment,there were 442 differentially expressed genes,332 were up-regulated and 120 were downregulated compared to LP without cadmium treatment.In the HP group,397 genes were differentially expressed between cadmium and cadmium-free treatment,in which 235 genes were up-regulated,and 162 genes were down-regulated.KEGG pathway enrichment analysis listed 20 pathways each.These differential gene enrichment pathways mainly include fatty acid synthesis and unsaturated fatty acid biosynthesis,gluconeogenesis and glycolysis,photosynthesis and other metabolic pathways.At the same time,analysis of transcription factors found 21 families of transcription factors,mainly including C3H family,C2C2 and C2H2 family,MYB family,AP2/ERF family and CAMTA family.In this paper,the toxic effect of the interaction of phosphorus and cadmium on Chlorella vulgaris was studied,the metabolic pathways and transcription factors related to cadmium stress were discovered by transcriptome analysis which provided a reference for elucidating the cadmium tolerance mechanism of Chlorella vulgaris.