No abstract

Alternaria brassicae is an important necrotrophic pathogen that infects the Brassicaceae family. A. brassicae, like other necrotrophs, also secretes various proteinaceous effectors and metabolites that cause cell death to establish itself in the host. However, there has been no systematic study of A. brassicae effectors and their roles in pathogenesis. The availability of the genome sequence of A. brassicae in public domain has enabled the search for effectors and their functional characterization. Nep1-like proteins (NLPs) are a superfamily of proteins that induce necrosis and ethylene biosynthesis. They have been reported from a variety of microbes including bacteria, fungi, and oomycetes. In this study, we identified two NLPs from A. brassicae viz. AbrNLP1 and AbrNLP2 and functionally characterized them. Although both AbrNLPs were found to be secretory in nature, they localized differentially inside the plant. AbrNLP2 was found to induce necrosis in both host and non-host species, while AbrNLP1 could not induce necrosis in both species. Additionally, AbrNLP2 was shown to induce pathogen-associated molecular pattern (PAMP)-triggered immunity in both host and non-host species. Overall, our study indicates that AbrNLPs are functionally and spatially (subcellular location) distinct and may play different but important roles during the pathogenesis of A. brassicae.

Codon usage bias is a ubiquitous phenomenon occurring at both, interspecies and intraspecies level in different organisms. P. knowlesi, whose natural host is long-tailed Macaque monkeys, has recently started infecting humans as well. The genome as well as coding sequence data of P. knowlesi is used to understand their codon usage pattern in the light of other human infecting Plasmodium species: P. vivax and P. falciparum. The different codon usage indicators: GC content, relative synonymous codon usage, effective number of codon and codon adaptation index are studied to analyze codon usage in the Plasmodium species. The codon usage pattern is found to be less conserved in studied Plasmodium species, and changes species to species at the genus level. The codon usage pattern of P. knowlesi shows similarity to P. vivax as compared to P. falciparum. The ENC vs. GC3 study indicates that compositional constraints and translation selection is the decisive forces responsible for shaping their codon usage. The studies Plasmodium species shows a higher usage of A/T ending optimal codons. This favors the codon bias in P. knowlesi and P. vivax is due to high selection pressure and in P. falciparum, the compositional mutational pressure is a dominant force. In a nutshell, our finding suggests that the more or less similar codon usage pattern of P. knowlesi and P. vivax may suggest the similar host invasion and immune evasion strategies for disease establishment.

No abstract

Alternaria brassicae is an important necrotrophic pathogen that infects the Brassicaceae family. A. brassicae, like other necrotrophs also secretes various proteinaceous effectors and metabolites that cause cell death to establish itself in the host. However, there has been no systematic study of A. brassicae effectors and their roles in pathogenesis. The availability of the genome sequence of A. brassicae has enabled the search for effectors and their functional characterisation. Nep1-like proteins are a superfamily of proteins that induce necrosis and ethylene biosynthesis. They have been reported from a variety of microbes including bacteria, fungi, and oomycetes. In this study, we identified two NLPs from A. brassicae viz. AbrNLP1 and AbrNLP2 and functionally characterised them. Although both AbrNLPs were found to be secretory in nature, they localised differentially inside the plant. AbrNLP2 was found to induce necrosis in both host and nonhost species, while AbrNLP1 could not induce necrosis in both species. Additionally, AbrNLP2 was shown to induce pathogen-associated molecular pattern (PAMP)-triggered immunity in both host and nonhost species. Overall, our study indicates that AbrNLPs are functionally and spatially (subcellular location) distinct and may play different but important roles during the pathogenesis of A. brassicae.