The Protein Composition of the Digestive Fluid from the Venus Flytrap Sheds Light on Prey Digestion Mechanisms

Abstract

The Venus flytrap (Dionaea muscipula) is one of the most well-known carnivorous plants because of its unique ability to capture small animals, usually insects or spiders, through a unique snap-trapping mechanism. The animals are subsequently killed and digested so that the plants can assimilate nutrients, as they grow in mineral-deficient soils. We deep sequenced the cDNA from Dionaea traps to obtain transcript libraries, which were used in the mass spectrometry-based identification of the proteins secreted during digestion. The identified proteins consisted of peroxidases, nucleases, phosphatases, phospholipases, a glucanase, chitinases, and proteolytic enzymes, including four cysteine proteases, two aspartic proteases, and a serine carboxypeptidase. The majority of the most abundant proteins were categorized as pathogenesis-related proteins, suggesting that the plant's digestive system evolved from defense-related processes. This indepth characterization of a highly specialized secreted fluid from a carnivorous plant provides new information about the plant's prey digestion mechanism and the evolutionary processes driving its defense pathways and nutrient acquisition. Molecular & Cellular

Long-read sequencing uncovers the adaptive topography of a carnivorous plant genome

“…Several other significantly enriched GOs are associated with this gene family. Cysteine proteases have been identified as major functional components of Venus flytrap (Dionaea muscipula) digestive fluid (72), reported in three D. muscipula transcriptomes (70,73,74), and structurally annotated for both Cape sundew (Drosera capensis) draft genome sequences (75,76) and D. muscipula (77). We found tandem clusters of homologous proteaseencoding genes in the U. gibba genome that had demonstrably undergone tandem duplication both before and after the most recent WGD event in U. gibba's evolutionary history (Fig.…”

“…Interestingly, a second class of chitinases, the class IV enzymes, was also highlighted as an expanded gene family under the GO category "cell wall," but none of these five genes showed trap-enhanced expression. Class IV chitinases are defense response proteins that represent a second family of chitinase (GH family 19) involved in plant carnivory (70,71). Finally, four genes encoding β-galactosidases (known from Nepenthes pitcher fluid) (57) appeared under the same GO category but did not have trap-enhanced expression in U. gibba.…”

Genome of the pitcher plant Cephalotus reveals genetic changes associated with carnivory

“…Previous studies on several digestive enzymes of Nepenthes spp., Drosera spp., Dionaea muscipula and Cephalotus indicate that pathogenesis-related proteins were co-opted for digestive function as well as for preventing microbial colonization of digestive fluid (refs [16][17][18][19] and refs in Supplementary Table 24). To further investigate the origin and evolution of digestive enzymes of Cephalotus and three other distantly related carnivorous plants (Drosera adelae, N. alata and Sarracenia purpurea), we sequenced fragments of digestive fluid proteins and identified 35 corresponding genes (Fig.…”

Evaluating the adaptive evolutionary convergence of carnivorous plant taxa through functional genomics

“…Phosphatase, aspartic peptidase, and cysteine peptidase, as catabolic enzymes found localized to the digestive fluids of other carnivorous taxa (Schulze et al, 2012;Rotloff et al, 2016), most likely have roles in direct digestive function. Ammonium tranpmembrane tranpport, while required in some amount by all plants, may be more vital for Utricularia, which must extract the concentrated nitrogenous products of digestion from an aquatic environment.…”