不同花色木棉转录组功能注释与分析

Functional annotation and analysis of transcriptome of Bombax ceiba with different flower colors

【目的】木棉是我国南方地区重要的观赏植物,研究不同时期花蕾和花朵的花瓣基因表达差异,揭示花色变异的遗传调控机制,为建立花色定向育种技术提供科学依据。【方法】以木棉不同发育时期深红色花和黄色花的花瓣为研究对象,利用Illumina HiSeqTM 4000开展转录组测序;分别采用DESeq2和Kyoto Encyclopedia of Genes and Genomes(KEGG)数据库进行差异表达基因鉴定和通路富集分析。【结果】测序共获得75190个单基因,4772个单基因能被公共数据库注释;基因功能富集分析显示,基因主要富集在基本功能预测、信号转导机制和转录后修饰、蛋白折叠、分子伴侣等通路。共获得不同时期差异表达基因10397个,显著富集在29个生物学通路,主要包括光合作用、代谢和植物激素信号转导通路等。其中,参与苯丙烷生物合成通路的差异表达基因有72个,参与类胡萝卜素、黄酮类生物合成通路和苯丙氨酸代谢通路的差异表达基因分别为25个,这些通路和基因均与花青素的生物合成相关;另有4个差异表达基因显著富集在甜菜碱的生物合成通路中。qRT-PCR数据验证了转录组数据的可靠性。【结论】(1)光合作用、代谢、植物激素信号转导、黄酮类生物合成、苯丙烷生物合成、苯丙氨酸代谢及能量代谢等通路相关基因可能参与花瓣的发育过程。(2)黄酮类生物合成通路相关基因在深红色花发育的花蕾中期与花朵期显著高表达,可能是花色呈现红色的主要原因。(3)类胡萝卜素生物合成通路的关键合成酶基因的部分家族成员在黄色花发育的花蕾期和花蕾中期显著高表达,可能是导致花色呈现黄色的主要原因。

[Objective]Bombax ceiba is an important ornamental plant in southern China.The aim of this study on the gene expression differences of flower buds and flowers in different stages was to reveal the genetic regulation mechanism of flower color variation,and provide a scientific basis for the establishment of flower color directional breeding technology.[Method]Taking the petals of dark-red-line and yellowline flowers of B.ceiba at different developmental stages as materials,and the Illumina HiSeqTM 4000 was used for transcriptome sequencing.DESeq2 and Kyoto Encyclopedia of Genes and Genomes(KEGG)databases were used to identify differentially expressed genes(DEGs)and enrichment pathways.[Result]A total of 75190 unique genes were obtained by sequencing,and 4772 single genes could be annotated by public databases.Gene function enrichment analysis showed that genes were mainly enriched in basic function prediction,signal transduction mechanism and post transcriptional modification,protein folding,molecular chaperone and other pathways,etc.A total of 10397 DEGs at different periods were obtained,which were significantly enriched in 29 biological pathways,mainly including photosynthesis,metabolic and plant hormone signal transduction pathways.Among them,there were 72 DEGs involved in the phenylpropanoid biosynthesis pathway,and 25 DEGs involved in carotenoid biosynthesis,flavonoid biosynthesis,phenylalanine metabolism,respectively.These pathways and genes were all related to the biosynthesis of anthocyanins.Another 4 DEGs were significantly enriched in the betalain biosynthesis.The results of qRT-PCR data verified the reliability of the transcriptome data.[Conclusion](1)The genes related to photosynthesis,metabolic pathways,plant hormone signal transduction pathways,flavonoid biosynthesis pathways,phenylpropane biosynthesis pathways and energy metabolism pathways may be involved in the development of petals.(2)The genes involved in flavonoid biosynthesis pathway are significantly highly expressed in the middle stage and bloom stage of dark-red line,which may be the main reason for the dark-red flower color.(3)Some family members of the key synthase genes of the carotenoid biosynthesis pathway are highly expressed in the bud and middle stage of yellow-flower line,which may be the main reason for the yellow flower color.