Moss Pathogenesis-Related-10 Protein Enhances Resistance to Pythium irregulare in Physcomitrella patens and Arabidopsis thaliana

Abstract

Plants respond to pathogen infection by activating signaling pathways leading to the accumulation of proteins with diverse roles in defense. Here, we addressed the functional role of PpPR-10, a pathogenesis-related (PR)-10 gene, of the moss Physcomitrella patens, in response to biotic stress. PpPR-10 belongs to a multigene family and encodes a protein twice the usual size of PR-10 proteins due to the presence of two Bet v1 domains. Moss PR-10 genes are differentially regulated during development and inoculation with the fungal pathogen Botrytis cinerea. Specifically, PpPR-10 transcript levels increase significantly by treatments with elicitors of Pectobacterium carotovorum subsp. carotovorum, spores of B. cinerea, and the defense hormone salicylic acid. To characterize the role of PpPR-10 in plant defense against pathogens, we conducted overexpression analysis in P. patens and in Arabidopsis thaliana. We demonstrate that constitutive expression of PpPR-10 in moss tissues increased resistance against the oomycete Pythium irregulare. PpPR-10 overexpressing moss plants developed less symptoms and decreased mycelium growth than wild type plants. In addition, PpPR-10 overexpressing plants constitutively produced cell wall depositions in protonemal tissue. Ectopic expression of PpPR-10 in Arabidopsis resulted in increased resistance against P. irregulare as well, evidenced by smaller lesions and less cellular damage compared to wild type plants. These results indicate that PpPR-10 is functionally active in the defense against the pathogen P. irregulare, in both P. patens and Arabidopsis, two evolutionary distant plants. Thus, P. patens can serve as an interesting source of genes to improve resistance against pathogen infection in flowering plants.

On plant defense signaling networks and early land plant evolution

“…In P. patens , infection by oomycete and fungal pathogens leads to up-regulation of the usual suspects of angiosperm defense signaling: PAL, Dirigent ( DIR ), Chalcone synthase ( CHS) and Pathogen related ( PR ) genes, as well as genes involved in JA and JA-precursor biosynthesis, such as LOX, AOS and OPR [62,63,137]. This is, however, not surprising, since infections with B. cinerea or two Pythium pathogens lead to OPDA production [62,63].…”

Adaptation Mechanisms in the Evolution of Moss Defenses to Microbes

“…It was recently shown that chitin oligosaccharides induce the expression of P. patens chitinase, which inhibits the growth of the fungus Trichoderma viride , suggesting that this enzyme could play a role in moss defense (Kobaru et al, 2016). Moss lines overexpressing PpPR-10 are more resistant to P. irregulare infection and accumulate unknown cell wall polymers, probably reinforcing the cell walls and increasing resistance to pathogens (Castro et al, 2016). PpPR-10 binds cytokinin (Gonneau et al, 2001), however, the biological relevance of this binding capacity in plant defense against pathogens is currently unknown.…”

Association analysis and in-vitro anti-fungal assay reveal a role for the Pinus monticola PR10 gene (PmPR10-3.1) in quantitative resistance to white pine blister rust

“…Causal genes underlying plant QR have been characterized with molecular roles in initial perception of pathogens (NB-LRR and RLK), signal transduction, and downstream defense and host metabolism [38]. As one group of defense components, PR10s have been identi ed in a number of plant species from moss, gymnosperms, to higher angiosperm plants [16]. Differential expression of PR10 genes in responses to biotic and abiotic stressors implied their potential roles in plant immunity systems.…”