BACKGROUND AND AIMS: Carnivorous plants can enhance photosynthetic efficiency in response to prey nutrient uptake, but the underlying mechanisms of increased photosynthesis are largely unknown. Here we investigated photosynthesis in the pitcher plant Nepenthes × ventrata in response to different prey-derived and root mineral nutrition to reveal photosynthetic constrains. METHODS: Nutrient-stressed plants were irrigated with full inorganic solution or fed with four different insects: wasps, ants, beetles or flies. Full dissection of photosynthetic traits was achieved by means of gas exchange, chlorophyll fluorescence and immunodetection of photosynthesis-related proteins. Leaf biochemical and anatomical parameters together with mineral composition, nitrogen and carbon isotopic discrimination of leaves and insects were also analysed. KEY RESULTS: Mesophyll diffusion was the major photosynthetic limitation for nutrient-stressed Nepenthes × ventrata, while biochemistry was the major photosynthetic limitation after nutrient application. The better nutrient status of insect-fed and root-fertilized treatments increased chlorophyll, pigment-protein complexes and Rubisco content. As a result, both photochemical and carboxylation potential were enhanced, increasing carbon assimilation. Different nutrient application affected growth, and root-fertilized treatment led to the investment of more biomass in leaves instead of pitchers. CONCLUSIONS: The study resolved a 35-year-old hypothesis that carnivorous plants increase photosynthetic assimilation via the investment of prey-derived nitrogen in the photosynthetic apparatus. The equilibrium between biochemical and mesophyll limitations of photosynthesis is strongly affected by the nutrient treatment.

• Klíčová slova
• Nepenthes, CO2 assimilation, Carnivorous, Rubisco, mesophyll conductance, mineral nutrition, nutrient stress, photosynthesis,
• MeSH
• chlorofyl MeSH
• fotosyntéza * MeSH
• listy rostlin MeSH
• masožravci * MeSH
• organické látky MeSH
• oxid uhličitý MeSH
• živiny MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• chlorofyl MeSH
• nepenthe MeSH Prohlížeč
• organické látky MeSH
• oxid uhličitý MeSH

Nepenthes regulates enzyme activities by sensing stimuli from the insect prey. Protein is the best inductor mimicking the presence of an insect prey. Carnivorous plants of the genus Nepenthes have evolved passive pitcher traps for prey capture. In this study, we investigated the ability of chemical signals from a prey (chitin, protein, and ammonium) to induce transcription and synthesis of digestive enzymes in Nepenthes × Mixta. We used real-time PCR and specific antibodies generated against the aspartic proteases nepenthesins, and type III and type IV chitinases to investigate the induction of digestive enzyme synthesis in response to different chemical stimuli from the prey. Transcription of nepenthesins was strongly induced by ammonium, protein and live prey; chitin induced transcription only very slightly. This is in accordance with the amount of released enzyme and proteolytic activity in the digestive fluid. Although transcription of type III chitinase was induced by all investigated stimuli, a significant accumulation of the enzyme in the digestive fluid was found mainly after protein and live prey addition. Protein and live prey were also the best inducers for accumulation of type IV chitinase in the digestive fluid. Although ammonium strongly induced transcription of all investigated genes probably through membrane depolarization, strong acidification of the digestive fluid affected stability and abundance of both chitinases in the digestive fluid. The study showed that the proteins are universal inductors of enzyme activities in carnivorous pitcher plants best mimicking the presence of insect prey. This is not surprising, because proteins are a much valuable source of nitrogen, superior to chitin. Extensive vesicular activity was observed in prey-activated glands.

• Klíčová slova
• Carnivorous plant, Chitin, Chitinase, Enzyme, Nepenthesin, Pitcher plant, Protease,
• MeSH
• Caryophyllales enzymologie   fyziologie   ultrastruktura   MeSH
• chitin metabolismus   MeSH
• chlorid amonný farmakologie   MeSH
• enzymy genetika   metabolismus   MeSH
• koncentrace vodíkových iontů MeSH
• masožravci MeSH
• membránové potenciály MeSH
• regulace genové exprese u rostlin * MeSH
• rostlinné proteiny genetika   metabolismus   MeSH
• sérový albumin hovězí metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• chitin MeSH
• chlorid amonný MeSH
• enzymy MeSH
• rostlinné proteiny MeSH
• sérový albumin hovězí MeSH