水稻幼苗响应褐飞虱和稻瘿蚊的转录组分析

Transcriptome analysis of rice seedlings responding to brown planthopper infestation and to gall midge infestation

【目的】筛选出同时响应褐飞虱和稻瘿蚊取食的基因,揭示水稻幼苗应对2种害虫时基因表达层面的差异,为后续挖掘广谱抗虫基因和解析水稻抗虫机制打下理论基础。【方法】以水稻品种9311为供试植物,分别对15日龄的水稻幼苗进行褐飞虱和稻瘿蚊接虫处理,观测幼苗表型,并通过转录组测序技术分别对褐飞虱接入后24 h和稻瘿蚊接入后7 d的水稻幼苗进行转录组测序。以水稻日本晴基因组作为参考基因组进行对比,利用FPKM法计算基因表达量,设定参数(|log_(2)FC|>1且P<0.05)筛选差异表达基因。结合基因差异表达分析和功能富集分析,研究水稻响应2种害虫的机制异同点。【结果】鉴定出响应褐飞虱取食的差异表达基因3963个,响应稻瘿蚊取食的差异表达基因1206个,有251个差异表达基因同时响应2种害虫,其中108个具有相同表达模式,143个具有相反表达模式。GO功能注释分析表明,褐飞虱取食显著影响植物体内细胞壁合成和缺水响应,而稻瘿蚊取食则对植物光合作用的影响更显著,具有相同表达模式的差异表达基因主要富集在光合作用、水杨酸合成、茉莉酸信号转导和伤害响应等生物学功能,而具有相反表达模式的差异表达基因仅富集在乙醛酸循环。KEGG信号通路富集分析表明,褐飞虱和稻瘿蚊取食均显著影响植物体内次生代谢物的合成,相同表达模式的差异表达基因富集到MAPK信号通路、植物激素信号转导通路及光合作用等6个通路,而相反表达模式的差异表达基因没有富集的通路。【结论】水稻应对褐飞虱和稻瘿蚊的基因表达调控存在相同点和不同之处,共响应2种害虫的调控通路可能在水稻抗虫过程中发挥重要作用。

【Objective】To screen out the functional genes that respond to both brown planthopper(BPH)infestation and rice gall midge(GM)infestation and reveal the difference of gene expression level in rice seedlings responding to the two pests,so as to provide theoretical basis for new broad-spectrum resistance and rice anti-insect mechanism.【Method】Rice 9311 was the tested rice variety.Fifteen-day-old seedlings were treated with BPH and GM respectively to observe seedling phenotypes and to sample for transcriptome which sequence was performed on rice seedlings that were collected 24 hours after BPH infestation and 7 days after GM infestation,respectively.Taking the genome of Nipponbare(MSU7)as a reference to align the sequences,the differentially expressed genes(DEGs)were screened by calculating the gene expression level in Fragments Per Kilobase per Million(FPKM),with(|log_(2)FC|≥1 and P≤0.05)as the parameter.Through gene differential expression analysis and functional enrichment analysis,the similarities and differences of rice response mechanisms to the two pests were identified.【Result】The results showed that 3963 genes were differentially expressed in BPH infestation and 1206 genes were differentially expressed in GM infestation.And 251 genes were found responsive to both pests,of which 108 genes with the same expression pattern and 143 genes with opposite expression patterns.GO enrichment analysis showed that:BPH infestation significantly influenced the cell wall biogenesis and the response to water deprivation in rice seedlings;seedlings of GM infestation enriched GO terms were mostly chloroplast or photosynthesis-related;the DEGs with the same expression patterns of two pest stresses were enriched to some biological processes such as photosynthesis,salicylic acid biosynthetic process,regulation of jasmonic acid mediated signaling pathway and response to wounding;whereas the DEGs with the opposite expression patterns of two pest stresses were enriched to glyoxylate cycle only.KEGG enrichment analysis indicated that:Both BPH infestation and GM infestationsignificantly affected the biosynthesis of secondary metabolites in seedlings;the DEGs with the same expression patterns in both treatments were enriched into six pathways mainly involved in MAPK signaling pathway,plant hormone signal transduction pathway,photosynthesis pathway;while no significant KEGG pathway was enriched in the DEGs with opposite expression patterns.【Conclusion】These results suggest that the common pathways in two pest infestations probably play an important role in rice resistance while similarities and differences exist in the regulations of gene expression between BPH infestation and GM infestation.