Methodology Identification of 18 genes encoding necrosis-inducing proteins from the plant pathogen Phytophthora capsici (Pythiaceae: Oomycetes)

Abstract

ABSTRACT. Phytophthora capsici is an aggressive plant pathogen that affects solanaceous and cucurbitaceous hosts. Necrosis-inducing Phytophthora proteins (NPPs) are a group of secreted toxins found particularly in oomycetes. Several NPPs from Phytophthora species trigger plant cell death and activate host defense gene expression. We isolated 18 P. capsici NPP genes, of which 12 were active during hypha growth from a Phytophthora stain isolated from pepper (Capsicum annuum) plants in China. The 18 predicted proteins had a sequence homology of 46.26%. The 18 Pcnpp sequences had a conserved GHRHDWE motif and fell into two groups. Eleven sequences in group 1 had two conserved cysteine residues, whereas the other seven sequences in group 2 lacked these two cysteine residues. A phylogenetic tree was constructed on the basis of the alignment of the predicted protein sequences of 52 selected NPP genes from oomycetes, fungi and bacteria from Genbank. The tree did not rigorously follow the taxonomic classification of the species; all the NPPs from oomycetes formed their own clusters, while fungal sequences were grouped into Identification of genes enconding NPP from P. capsici two separate clades, indicating that based on NPPs, we can separate oomycetes from fungi and bacteria, and that expansion of the NPP family was a feature of Phytophthora evolution.

RNA-Seq Reveals Infection-Related Gene Expression Changes in Phytophthora capsici

“…has been noted in whole-genome analyses and the size of the NLP family in P. infestans (n  = 27), P. sojae (n  =  39), and Phytophthora ramorum (n  =  59) has been estimated through annotation [17], [18]. Recently, 18 putative NLP genes have been cloned from P. capsici strain SD33 [77]. However, the exact number of functional or ‘real’ genes encoding NLPs in P. capsici is yet to be determined and their exact functional roles in P. capsici virulence remain to be elucidated.…”

Characterization of necrosis-inducing NLP proteins in Phytophthora capsici

“…Eighteen NLP-encoding genes (GenBank accession numbers HM543167 to HM543184) were identified from P. capsici SD33, RT-PCR detected expression for all but seven [51], of which 11 were selected for further functional analysis during P. capsici interactions with plants (Table 1). …”

Purification of p47f, a Necrosis‐Inducing Protein Fraction from the Secretome of Phytophthora capsici

“…The extracellular group includes secreted effectors such as well‐known protease inhibitors, cysteine proteases, subtilisin‐like proteases and aspartic proteases, which act on targets located in the extracellular space (Kamoun ; van der Hoorn and Kamoun ), as well as the 18 recently described necrosis‐inducing Phytophthora proteins (PcNpp) and the nine pectin methylesterases (Pme) identified in P. capsici strain SD33 (Feng et al. ; Li et al. ).…”

“…It has been proposed that secreted necrosis‐promoting proteins (NPPs) in P. capsici contribute to the transition from biotrophy to necrotrophy; twelve PcNpp genes are expressed in P. capsici during infection, but their functional roles in the virulence of the oomycete remain unclear (Feng et al. ). Additionally, pectin methylesterase ( PcPme ) genes are also expressed during infection, and it has been shown that the exposure of plant tissue to PcPme proteins results in collapsing of the tissue and cell death (Lamour et al.…”