含热带种质玉米自交系ZOL-1胚乳发育的转录组研究

Transcriptome analysis of endosperm development in tropical germplasm maize line ZOL-1

【目的】研究含热带种质玉米自交系胚乳发育分子机制及相关调控网络。【方法】通过高通量RNA-seq测序技术,对热带血缘玉米自交系ZOL-1在授粉后5、10、15、20、25、30 d 6个时期的胚乳转录组进行比较,得到的差异表达基因进行KEGG与GO功能注释,并对FPKM平均值大于1的基因进行时间序列分析。【结果】玉米自交系ZOL-1胚乳发育在授粉后25~30 d时籽粒长、宽、厚增长速率最快,增长率分别达到15.9%、16.1%和10.2%。经过转录组测序和同参考基因组比对,过滤后reads占比至少为83.99%,测序质量和组装效果均较好。按照连续比较系统方法,在10 d_VS_5 d、15 d_VS_10 d、20 d_VS_15 d、25 d_VS_20 d和30 d_VS_25 d分别检测到7129、5252、4254、775和312个差异表达基因。GO功能注释表明,差异表达基因主要分布于细胞分化过程、代谢过程、催化活性和细胞器等条目中。KEGG功能富集分析显示,差异表达基因主要富集在能量代谢、碳水化合物代谢、碳代谢、氨基酸代谢、信号转导等与胚乳发育相关的通路。通过对FPKM平均值大于1的基因进行时间序列分析,19554个基因共划分为10个Clusters,并在Cluster 7鉴定出8个淀粉合成酶相关基因,它们的表达量在授粉后15 d时开始显著提升,此后保持较高表达水平。【结论】玉米自交系胚乳发育可能主要受下调基因表达调控,在授粉后15 d前后胚乳的发育模式发生变化,转录组有重新编程的迹象,同时挖掘到玉米淀粉生物合成相关基因8个,有利于研究胚乳发育的分子调控机理。

【Objective】The present paper aims to investigate the molecular mechanisms and associated regulatory networks involved in endosperm development for the tropical maize inbred line.【Method】The study employed high-throughput RNA-Seq sequencing technology to compare the endosperm transcriptome of the tropical inbred maize line ZOL-1 at six stages after pollination,including 5(day after pollination),10,15,20,25 and 30 days.Differentially expressed genes were annotated with KEGG and GO functions,and time-series analysis was conducted on genes with an average FPKM value greater than 1.【Result】The endosperm development of the maize inbred line ZOL-1 exhibited the fastest growth rate in grain length,width,and thickness at 25-30 days after pollination,with growth rates reaching 15.9%,16.1%and 10.2%,respectively.Following transcriptome sequencing and comparison with the reference genome,the percentage of filtered reads was at least 83.99%,indicating good sequencing quality and assembly.A total of 7129,5252,4254,775 and 312 differentially expressed genes were identified between 10 d_VS_5 d,15 d_VS_10 d,20 d_VS_15 d,25 d_VS_20 d and 30 d_VS_25 d,based on the sequential comparison system approach.GO functional annotation indicated that the differentially expressed genes were mainly involved in cell differentiation process,metabolic process,catalytic activity and organelles.KEGG functional enrichment analysis revealed that differentially expressed genes were mainly enriched in pathways related to energy metabolism,carbohydrate metabolism,carbon metabolism,amino acid metabolism,signal transduction,and other processes associated with endosperm development.Through time-series analysis of genes with an FPKM mean greater than 1,19554 genes were classified into 10 clusters.In Cluster 7,eight starch synthase-related genes were identified,showing a significant increase in expression starting at the 15-day period and maintaining a high expression level thereafter.【Conclusion】The regulation of endosperm development in maize self-incompatible lines appears to be primarily governed by the expression of down-regulated genes.The developmental pattern of the endosperm undergoes a significant change before and after 15 days,indicating a transcriptome reprogramming.Additionally,the study identifies eight genes associated with maize starch biosynthesis,providing valuable insights into the molecular regulatory mechanisms of endosperm development.