過去植物病理學研究，著重在病原菌接觸植物之條件下，探討植物的病徵、反應與抵抗機制，但對於病原菌產生的氣味對植物之影響則較少見。我們從野外土壤中純化出產氣桿菌(Enterobacter aerogenes)，其氣味能有效抑制菸草生長、降低葉綠素含量、促使細胞死亡並誘導過氧化物質累積。利用次世代定序技術分析菸草在Enterobacter aerogenes氣味下之轉錄圖譜，發現有1320條轉錄產物(transcripts)會受菌味處理而誘導表現，並參與在WRKY轉錄調控、粒線體電子傳遞鏈、Cytochrome P450解毒機制與鈣離子訊息傳遞等相關路徑。NbExo70為菸草中的胞吐複合體成員，其同樣會受Enterobacter aerogenes氣味處理而表現上提，若利用基因靜默技術壓低NbExo70表現量，將會降低菸草對Enterobacter aerogenes氣味的耐受性，並減緩菌味誘導的氧化物質累積現象。經由比較野生型與NbExo70靜默型菸草在Enterobacter aerogenes氣味下的轉錄圖譜，發現有162條NbExo70依賴型轉錄產物(transcripts)，其只在野生型菸草中會表現上提，過去研究得知粒線體電子傳遞鏈複合體1號的運作，能誘導植物累積過氧化物質，分析結果顯示，NbExo70依賴型轉錄產物(transcripts)有17條屬於粒線體電子傳遞鏈複合體1號中的成員。本研究結果可證明NbExo70參與Enterobacter aerogenes氣味下的反應機制，並透過直接或間接影響粒線體電子傳遞鏈複合體1的基因表現，來誘導過氧化物質累積。

Previous studies of plant pathology focusing on plant and pathogen direct surface-to-surface contact. However, the effects of volatile chemicals on plants are rare. In this stufy, we found volatiles of Enterobacter aerogenes significantly inhibited the growth, and decreased the content of chlorophyll in Nicotiana benthamiana. This volatiles also induced the cell death and H2O2 production. Transcriptome profiling revealed 1320 transcripts were significantly responsed to 12 hours exposure to E. aerogenes volatiles. These transcripts primary involved in WRKY transcriptional regulation, mitochondrial electron transport chain, cytochrome P450 in detoxification mechanism and calcium signaling pathway. NbExo70 is a member of exocytosis complex in N. benthamiana. This gene also was responsed to E. aerogenes volatiles. Using the gene silencing technique to knock down NbExo70 would reduce the tolerance and H2O2 production under E. aerogenes volatiles. We also compared the transcriptome profiles of wild-type and NbExo70 silencing tobacco under the E. aerogenes volatiles. We found 162 NbExo70-dependent transcripts were specifically induced in the wild-type tobacco plants. Seventeen out of 162 transcripts involved in mitochondrial electron transport chain complex I that could cause the accumulation of H2O2. In this study, we proposed that NbExo70 were involved in response to E. aerogenes volatiles. Moreover, NbExo70 might directly or indirectly affect gene expression of members in mitochondrial electron transport chain complex I to induce H2O2 production under the E. aerogenes volatiles.

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