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

【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(|log₂ 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 photosynthesisrelated;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.