CNR转录因子在番茄果实成熟过程中的功能

Function of Transcription Factor CNR in the Ripening Process of Tomato Fruit

SPL转录因子在植物中广泛存在并参与植物生长、发育和成熟过程,CNR是SPL转录因子家族中的一个成员,其作用机制尚不清楚。通过RNA-seq、qRT-PCR和染色质免疫共沉淀技术(ChIP)确定转录因子CNR直接作用的新的靶基因,旨在揭示番茄果实成熟过程中CNR的转录调控网络。通过RNA-seq筛选出野生型AC和突变体Cnr番茄果实中有10223个差异表达基因,这些基因涉及番茄果实生长和发育的许多方面。qRT-PCR验证的结果和转录组测序数据一致,发现甘露聚糖-1,4-β-甘露糖苷酶基因、亚油酸9S-脂氧合酶基因、果胶酯酶基因、八氢番茄红素合成酶基因、1-氨基环丙烷-1-羧酸合成酶基因、乙烯响应因子基因、多聚半乳糖醛酸酶基因和果胶裂解酶基因在AC和Cnr番茄果实中的表达量有显著差异。同时,在这些基因的启动子区域发现了转录因子CNR的结合位点GTAC基序,揭示CNR可能直接调控这些基因的转录,最后通过ChIP分析进一步验证了这个假设。转录因子CNR新靶基因涉及脂代谢、细胞壁、番茄红素合成和乙烯生物合成途径,CNR通过这些途径在番茄果实成熟过程中起作用。

SPL transcription factors are widely existing in plants and are involved in plant growth,development and maturation.CNR is a member of SPL transcription factor family,and its mechanism of action is still unclear.The novel target genes of CNR were determined by RNA-seq,qRT-PCR and chromatin immunoprecipitation(ChIP)assay,which is aimed to uncover the transcriptional regulatory network of CNR during the ripening process of tomato fruit.About 10,223 differentially expressed genes between wild type AC and mutant cnr were achieved by RNA-seq,and these genes were involved in many aspects of tomato fruit growth and development.The results of qTR-PCR were basically consistent with transcriptome sequenced data.Particularly there were significantly large differential expression levels of gene Mannan endo-1,4-beta-mannosidase,Linoleate 9S-lipoxygenase,Pectinesterase,Phytoene synthase,1-aminocyclopropane-1-carboxylate synthase,Ethylene response factor,Polygalacturonase and Pectate lyase between AC and cnr.In addition,GTAC motif,a CNR-binding site,was found in the promoter regions of these genes,suggesting that CNR possibly directly regulated their transcriptions,and this supposition was further verified by ChIP analysis.Functional annotations of CNR target genes uncovered the specific role of CNR during the ripening process of tomato fruit via the pathways of lipid metabolism,cell wall,lycopene synthesis and ethylene biosynthesis.