微生物在臺灣小毛氈苔的分布及其影響

Abstract

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Carnivorous plants secrete digestive fluid for nutrient acquisition. Although the fluid provides extreme conditions with low pH value and hydrolytic enzymes, several studies have found that the microbial community inside the mucilage plays an important role for prey digestion. Drosera spatulata is a carnivorous plant that secretes mucilage to stick to insects. Its leaves are covered with “tentacles” ending in glandular heads. These heads include glandular cells which produce sticky mucilage. Unlike pitcher plants containing digestive fluid inside modified foliar structures, the mucilage of D. spatulata is exposed to the environment. External influences are especially important in determining the distribution and abundance of microorganisms. In this study, we characterised the microbial communities of D. spatulata mucilage from northern Taiwan by using amplicon sequencing. To identify the relationship between D. spatulata and microorganisms, we inoculated microbes on D. spatulata and analyzed their gene expression. As the result, we found that the fungus Acrodontium crateriforme is the ecologically dominant species in D. spatulata mucilage. Based on the transcriptomes when encountering prey insects, we revealed a high degree of genetic co-option in each species during fungus-plant coexistence and digestion. Expression patterns of the holobiont during digestion further revealed synergistic effects in several gene families including fungal aspartic and sedolisin peptidases, which facilitate the digestion of sundew’s prey, as well as transporters and dose-dependent responses in plant genes involved in the jasmonate signalling pathway. This study shows that botanical carnivory is defined by multidimensional adaptations that correlate with interspecific interactions.