Carnivorous Nutrition in Pitcher Plants (Nepenthes spp.) via an Unusual Complement of Endogenous Enzymes

Linda Lee, Ye Zhang, Brittany Ozar, Christoph W Sensen, David C Schriemer

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Plants belonging to the genus Nepenthes are carnivorous, using specialized pitfall traps called "pitchers" that attract, capture and digest insects as a primary source of nutrients. We have used RNA sequencing to generate a cDNA library from the Nepenthes pitchers, and applied it to mass spectrometry-based identification of the enzymes secreted into the pitcher fluid, using a non-specific digestion strategy superior to trypsin in this application. This first complete catalog of the pitcher fluid sub-proteome includes enzymes across a variety of functional classes. The most abundant proteins present in the secreted fluid are proteases, nucleases, peroxidases, chitinases, a phosphatase and a glucanase. Nitrogen recovery involves a particularly rich complement of proteases. In addition to the two expected aspartic proteases, we discovered three novel nepenthensins, two prolyl endopeptidases that we name neprosins, and a putative serine carboxypeptidase. Additional proteins identified are relevant to pathogen-defense and secretion mechanisms. The full complement of acid-stable enzymes discovered in this study suggests that carnivory in the genus Nepenthes can be sustained by plant-based mechanisms alone, and does not absolutely require bacterial symbiosis.

Original languageEnglish
JournalJournal of Proteome Research
Publication statusPublished - 20 Jul 2016

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