AOBPreview originally published online on July 30, 2007
Annals of Botany 2007 100(3):527-536; doi:10.1093/aob/mcm145
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Carnivorous Syndrome in Asian Pitcher Plants of the Genus Nepenthes
*ováDepartment of Plant Physiology, Faculty of Natural Sciences, Comenius University, Mlynská dolina B-2, SK-84215 Bratislava, Slovak Republic
* For correspondence. E.mail pavlovic{at}fns.uniba.sk
Received: 12 March 2007 Returned for revision: 18 April 2007 Accepted: 23 May 2007 Published electronically: 30 July 2007
Background and Aims: Pitcher plants Nepenthes alata and N. mirabilis are carnivorous species with leaves composed of a photosynthetic part (lamina) and a pitcher trap. This characteristic permitted direct physiological and anatomical comparison between these two distinct parts of the leaves to determine those features involved in the ‘carnivorous syndrome’, which include low net photosynthetic assimilation rate (AN) and low photosynthetic nitrogen use efficiency (PNUE).
Methods: Photosynthetic rate (AN) and respiration rate (Rd) were measured gasometrically, chlorophyll concentration was determined spectrophotometrically and nitrogen concentration was determined using a CHN elemental analyser in lamina and trap separately. Anatomy of N. alata was observed using light, fluorescence and transmission electron microscopy. AN, foliar nitrogen and chlorophyll concentration were also compared with values for other carnivorous plant species (genera Sarracenia, Drosera) that combine both autotrophic and carnivorous functions into the same physical organ.
Key Results: It was found that the AN in Nepenthes lamina was low and PNUE was only slightly higher or similar in comparison with other carnivorous plants. It was not observed that the pitcher had a higher Rd than the lamina, but AN in the pitcher was significantly lower than in the lamina. Nepenthes possesses a cluster of characters that could result in reduced photosynthesis in the pitcher and be responsible for carnivorous function of the leaf: replacement of chlorophyll-containing cells with digestive glands, low chlorophyll and nitrogen concentration, compact mesophyll with a small portion of intercellular spaces, absence of palisade parenchyma and low stomatal density.
Conclusion: Low photosynthetic capacity, nitrogen efficiency, chlorophyll and nitrogen concentration of Nepenthes pitchers was found, together with a set of features that characterized the carnivorous syndrome. Dual use of leaves for photosynthesis and nutrient gain can decrease photosynthetic efficiency in carnivorous plants in general.
Key words: chlorophyll concentration, cost/benefit analysis, Drosera capensis, leaf anatomy, leaf nitrogen concentration, Nepenthes alata, Nepenthes mirabilis, pitcher plant, photosynthetic rate, respiration rate, Sarracenia psittacina, stomatal density
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  O. O. Osunkoya, S. D. Daud, and F. L. Wimmer Longevity, Lignin Content and Construction Cost of the Assimilatory Organs of Nepenthes Species Ann. Bot., August 28, 2008; (2008) mcn162v1. [Abstract] [Full Text] [PDF]
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