PlMAPK10, a Mitogen-Activated Protein Kinase (MAPK) in Peronophythora litchii, Is Required for Mycelial Growth, Sporulation, Laccase Activity, and Plant Infection

Abstract

Mitogen-activated protein kinase (MAPK) pathways are ubiquitous and evolutionarily conserved signal transduction modules directing cellular respond to a diverse array of stimuli, in the eukaryotic organisms. In this study, PlMAPK10 was identified to encode a MAPK in Peronophythora litchii, the oomycete pathogen causing litchi downy blight disease. PlMAPK10, containing a specific and highly conserved dual phosphorylation lip sequence SEY (Serine-Glutamic-Tyrosine), represents a novel group of MAPKs as previously reported. Transcriptional profiling showed that PlMAPK10 expression was up-regulated in zoospore and cyst stages. To elucidate its function, the PlMAPK10 gene was silenced by stable transformation. PlMAPK10 silence did not impair oospore production, sporangium germination, zoospore encyst, or cyst germination but hindered hyphal growth, sporulation, pathogenicity, likely due to altering laccase activity. Over all, our results indicated that a MAPK encoded by PlMAPK10 gene in P. litchii is important for pathogenic development.

An RXLR effector PlAvh142 from Peronophythora litchii triggers plant cell death and contributes to virulence

“…As a hemibiotrophic pathogen, P. litchii undergoes biotrophic and necrotrophic phases during infection. However, fewer studies have been conducted on the functions of P. litchii genes, hence there is scarcity of information about its pathogenesis and the litchi-P. litchii interaction mechanisms (Jiang et al, , 2018Kong et al, 2019). The identification and/or investigation of RXLR effectors in P. litchii lags behind that for other Phytophthora and downy mildew species, with only bioinformatics prediction of 245 putative RXLR effector genes (Ye et al, 2016).…”

The Mitogen-Activated Protein Kinase PlMAPK2 Is Involved in Zoosporogenesis and Pathogenicity of Peronophythoralitchii

“…However, the function of MAPKs in development and pathogenicity of oomycetes are rarely known. In oomycetes, PsMAPK1, PsSAK1, PsMPK7 and MAPK10 showed various functions in vegetative growth, zoospore viability, stress tolerance, detoxification of reactive oxygen species, cyst germination, sexual reproduction, laccase activity and pathogenicity [10][11][12][13]. In this study, we identified the PlMAPK2 and found that its orthologs in oomycete are functional unknown MAPKs.…”

“…We further examined the transcriptional levels of 8 laccase-encoding genes found that 3 of them, Pl104952, Pl106183 and Pl111417, were dramatically down-reg in PlMAPK2 mutants, while Pl103272 and Pl106923 were slightly up-regulat In fungi, laccases participate in the oxidation of antibiotics such as flavonoids and phytoalexins and contribute to the virulence of pathogen [17]. In oomycetes, the laccase activity is also associated with the plant infection [5,10,18]. Here we tested the laccase activity of PlMAPK2 mutants and found that these mutants showed decreased laccase activity (Figure 7A).…”

“…MAPK cascades participate in the response to diverse stresses, developmental processes and infection of fungi and oomycetes [9,10]. In P. sojae, PsMAPK1 is involved in vegetative growth, zoosporogenesis and virulence [11].…”

“…PsMPK7 is required for stress tolerance, detoxification of reactive oxygen species (ROS), cyst germination, sexual reproduction and pathogenicity [13]. Silencing of P. litchii MAPK10 led to defects in mycelial growth, sporulation, laccase activity and plant infection [10]. These studies demonstrated that MAPK signaling is critical for development and pathogenicity of plant pathogenic oomycete; however, the MAPK pathways in oomycetes remain largely unknown.…”