Functional characterization of a class III acid endochitinase from the traps of the carnivorous pitcher plant genus, Nepenthes

Carnivory in plants is an adaptation strategy to nutrient-poor environments and soils. Carnivorous plants obtain some additional mineral nutrients by trapping and digesting prey; the genus Nepenthes is helped by its specialized pitcher traps. To make the nutrients available, the caught prey needs to be digested, a process that requires the concerted activity of several hydrolytic enzymes. To identify and investigate the various enzymes involved in this process, fluid from Nepenthes traps has been analysed in detail. In this study, a novel type of Nepenthes endochitinase was identified in the digestion fluid of closed pitchers. The encoding endochitinase genes have been cloned from eight different Nepenthes species. Among these, the deduced amino acid sequence similarity was at least 94.9%. The corresponding cDNA from N. rafflesiana was heterologously expressed, and the purified protein, NrChit1, was biochemically characterized. The enzyme, classified as a class III acid endochitinase belonging to family 18 of the glycoside hydrolases, is secreted into the pitcher fluid very probably due to the presence of an N-terminal signal peptide. Transcriptome analyses using real-time PCR indicated that the presence of prey in the pitcher up-regulates the endochitinase gene not only in the glands, which are responsible for enzyme secretion, but at an even higher level, in the glands’ surrounding tissue. These results suggest that in the pitchers’ tissues, the endochitinase as well as other proteins from the pitcher fluid might fulfil a different, primary function as pathogenesis-related proteins

Plastome-wide rearrangements and gene losses in carnivorous Droseraceae

The plastid genomes of four related carnivorous plants (Drosera regia, Drosera erythrorhiza, Aldrovanda vesiculosa and Dionaea muscipula) were sequenced to examine changes potentially induced by the transition to carnivory. The plastid genomes of the Droseraceae show multiple rearrangements, gene losses and large expansions or contractions of the inverted repeat. All the ndh genes are lost or non-functional, as well as in some of the species, clpP1, ycf1, ycf2 and some tRNA genes. Uniquely amongst land plants, the trnK gene has no intron. Carnivory in the Droseraceae coincides with changes in plastid gene content similar to those induced by parasitism and mycoheterotrophy, suggesting parallel changes in chloroplast function due to the similar switch from autotrophy to (mixo-) heterotrophy. A molecular phylogeny of the taxa based on all shared plastid genes indicates that the ‘snap-traps’ of Aldrovanda and Dionaea have a common origin

SYSTEMATISCHE UNTERSUCHUNGEN AN MITTELEUROP\uc4ISCHEN POLYGALA-ARTEN

Volume: 20Start Page: 205End Page: 42

Bemerkungen zur Karyologie der Gattung Lysimachia L. Chromosomenzahlen und Evolution

Volume: 28Start Page: 297End Page: 31

Zyto- und chemotaxonomische Studien an Lysimachia nennorum L. und Lysimachla azorica H\uf6rnern, ex Hooker

Volume: 27Start Page: 33End Page: 4

A cytological study of the genus Nepenthes L. (Nepenthaceae)

Volume: 4Start Page: 169End Page: 17