Genes for carnivory : a comparative study on the local duplication of papain-like cysteine proteases in carnivorous plants

• Main Author: Tan, Qiao Wen
• Other Authors: Victor Anthony Albert
• Format: Final Year Project
• Language: English
• Published: 2018
• Subjects: DRNTU::Science::Biological sciences::Evolution
• Online Access: http://hdl.handle.net/10356/74104
• Institution: Nanyang Technological University

Mechanisms for carnivory in carnivorous plants have been proposed to arise from defence related mechanisms and several genes have been identified from proteomic analyses thus far. Carnivory confers the advantage of utilising prey as an additional nitrogen source in nutrient poor environments. Thus, the presence of protein degrading enzymes such as papain-like cysteine proteases (PLCPs) in trap fluids is not surprising. With the genomes of Drosera capensis and Drosera regia sequenced recently, a maximum likelihood phylogenetic analysis of 444 PLCPs from 16 taxa reveals multiple taxa-specific gene expansion in the PAP/SAG12 subfamily of PLCPs. A Droseraceae-specific expansion of PAP/SAG12 genes including 4 previously identified trap proteins suggests that the adoption of PLCPs for carnivory may have occurred in the last common ancestor of D. capensis and D. regia or earlier. Convergent evolution for rapid upregulation and expression of genes in this subclade can also be hypothesized from the recent tandem duplications that occurred independently in D. capensis and D. regia. Through the comparison of Drosera PLCPs with carnivorous plants Utricularia gibba and Cephalotus follicularis, molecular mechanisms adopted for carnivory appear to be, at least in part, convergent in the former (which likely uses PLCPs) and an alternative mechanism (aspartic proteases) seems to be more probable in the latter.