Patterns of molecular evolution in pathogenesis-related proteins

Abstract

The genes encoding 13 classes of pathogenesis-related (PR) proteins were examined for positive selection using maximum-likelihood (ML) models of codon substitution. The study involved 194 sequences from 54 species belonging to 37 genera. Although the sizes of the sequences examined varied from 237 bp for PR12 to 1,110 bp for PR7, most classes (9 out of 13) contained sequences made up of more than 400 nucleotides. Signs of positive selection were obtained for sites in PR proteins 4, 6, 8, 9 and 15 using an ML-based Bayesian method and likelihood ratio tests. These results confirm the importance of positive selection in proteins related to defense mechanisms already observed in a wide array of organisms

Carbohydrate, phenolic and antioxidant level in relation to chlorophyll a content in oilseed winter rape (Brassica napus L.) inoculated with Leptosphaeria maculans

“…The decrease in chlorophyll content evoked by pathogenic fungi was also observed by other authors (Rasmussen and Sheffer 1988;Moriondo et al 2005;Mandal et al 2009a;Zhao et al 2011). Table 4 Changes in the content ([mg g -1 (DW)]) of chlorophyll a (Chla), chlorophyll b (Chlb), total chlorophyll (Chla+b) and carotenoids (Crts) observed 7 and 14 days after the inoculation (I) with L. maculans spores in the leaves of studied cultivars Apart from ROS, other significant predictors of hostpathogen interaction are pathogenesis related (PR) proteins (Scherer et al 2005). Enhanced activity of chitinase and β-1,3-glucanase (Table 1) observed in this experiment 7 and 14 days after the inoculation with L. maculans spores is probably a manifestation of the systemic plant response to the infection, and not a sign of the fungal pathogen growth in the plant cells.…”

Differential expression of genes identified from Poncirus trifoliata tissue inoculated with CTV through EST analysis and in silico hybridization

“…Another overexpressed gene in the presence of the CTV was the peroxidase encoding prxr1. Peroxidase prxr1 is considered a PR9 peroxidase that probably strengthens plant cell walls by catalyzing lignin deposition in reaction to microbial attacks (Scherer et al, 2005).…”

Patterns of molecular evolution and predicted function in thaumatin-like proteins of Populus trichocarpa

“…Many pathogen recognition genes, such as plant R-genes, have been reported to undergo positive selection (McDowell et al 1998;Meyers et al 1998;Wang et al 1998;Bergelson et al 2001;Ford 2001;Mondragón-Palomino et al 2002). Some plant PR proteins that kill or resist pathogens directly, such as chitinases I (Bishop et al 2000;Scherer et al 2005), chitinases II, chitinases III, proteinaseinhibitor, peroxidase, and oxalate oxidase (Scherer et al 2005), have been reported to undergo positive selection. However, negative selection has been detected in other PR proteins, such as b-1,3-glucanase, defensin, lipid-transfer protein, and some TLPs (28 sequences in 15 different species) (Scherer et al 2005).…”