Transcriptome analysis of Camellia oleifera in response to different light intensities

【Objective】To analyze the molecular regulatory network of Camellia oleifera in response to changes in light intensity environment,and provide a basis for the construction of high-light-efficiency metabolic network and the mining of key genes in Camellia oleifera,this study analyzed the transcriptome sequencing of C. oleifera in response to different light intensities.【Method】 The photosynthetic physiological indexes of C. oleifera leaves were determined under different light intensities. And transcriptome sequencing was performed using high-throughput sequencing technology, and the differentially expressed genes(DEGs)in the pathways related to photosynthesis,primary metabolism,secondary metabolism and hormone synthesis were discovered and their expression characteristics were analyzed.【Result】 With the decrease of light intensity,the net photosynthetic rate,stomatal conductance and carbon content of C. oleifera leaves decreased,while the intercellular CO₂ concentration,chlorophyll a,chlorophyll b and nitrogen contents increased. GO function annotation results showed that C. oleifera adapted to low light intensity environment by up-regulating the expression of DEGs related to biological process,cellular component and molecular function. Mapman metabolic pathway enrichment analysis showed that the C. oleifera up-regulated DEGs expression in light-harvesting complex,electron transport protein,carbohydrate decomposition and nitrogen metabolism pathways,and down-regulated DEGs expression in photorespiration and tricarboxylic acid cycle pathways to cope with the deficiency of carbon assimilation ability. With the decreasing of light intensity,the DEGs in abscisic acid(ABA),brassinolide(BR),auxin(IAA),jasmonic acid(JA) and gibberellin(GA)synthesis pathways were up-regulated,while the DEGs in mitogen(CTK)decomposition pathway were down-regulated. And the DEGs in flavonoids, phenylpropanoids, phenols, terpenoids, alkaloids and other secondary metabolic pathways were down-regulated. A total of 1372 transcription factors were identified,among which the largest number of family members were bHLH and ERF with 115 and 100 members,respectively.【Conclusion】The photosynthetic carbon assimilation ability of C. oleifera decreases with the decrease of light intensity. C. oleifera responds to low light intensity environment by up-regulating DEGs expression in light-harvesting complex,electron transport protein, carbohydrate decomposition,nitrogen metabolism and various types of hormone synthesis,and down-regulating DEGs expression in respiration and secondary metabolism,and regulating two major transcription factors,bHLH and ERF,at molecular level.