The root pathogen Aphanomyces euteiches secretes modular proteases in pea apoplast during host infection

Abstract

To successfully colonize the host, phytopathogens have developed a large repertoire of components to both combat the host plant defense mechanisms and to survive in adverse environmental conditions. Microbial proteases are predicted to be crucial components of these systems. In the present work, we aimed to identify active secreted proteases from the oomycete Aphanomyces euteiches, which causes root rot diseases on legumes. Genome mining and expression analysis highlighted an overrepresentation of microbial tandemly repeated proteases, which are upregulated during host infection. Activity Based Protein Profiling and mass spectrometry (ABPP-MS) on apoplastic fluids isolated from pea roots infected by the pathogen led to the identification of 35 active extracellular microbial proteases, which represents around 30% of the genes expressed encoding serine and cysteine proteases during infection. Notably, eight of the detected active secreted proteases carry an additional C-terminal domain. This study reveals novel active modular extracellular eukaryotic proteases as potential pathogenicity factors in Aphanomyces genus.

Transcriptomic analysis identifies candidate genes for Aphanomyces root rot disease resistance in pea

“…JA signaling has been associated with plant defense to necrotrophic pathogens [ 41 , 42 ]. Aphanomyces euteiches undergoes a shift from a biotrophic to a necrotrophic lifestyle in later stages of infection [ 10 ]. In soybean roots, higher levels of JA were observed at later time points after inoculation with the oomycete Phytophthora sojae [ 43 ].…”

“…In the first six days of infection, the biotrophic phase, the pathogen colonizes the cortex root tissue of the host plant. The necrotrophic growth phase is initiated by the invasion of the stele and vascular tissues, leading to the typical browning of the roots and premature plant death [ 9 , 10 ]. The cycle ends with the production of sexual oospores in declining host tissues [ 11 ].…”

The Exceptionally Large Genomes of the Fabeae Tribe: Comparative Genomics and Applications in Abiotic and Biotic Stress Studies

“…After the publication of the first pea genome [13], several studies on legume biotic stresses have been favored by the availability of a pea reference genome. Genetic and genomic studies on legume fungal diseases have been performed in aerial fungal diseases, such as powdery mildew [61][62][63], white mold [69], rust [71,72], ascochyta blight [93,94], and also in root diseases, like fusarium wilt and root rot [76,77,95] and Aphanomyces root rot (caused by oomycetes) [79][80][81]. In these studies, the Caméor pea genome was used for SNP calling, location of SNP physical positions, identification of candidate genes underlying QTLs, and syntenic studies aiming at genetic linkage maps validation and location of ortholog genes of interest by comparative mapping.…”

“…Proteomic studies also used pea cv. Caméor genome for identification of proteases secreted by the root pathogen Aphanomyces euteiches during pea infection, using comparison of MS/MS spectral against the reference genome [80,96].…”