The Loricrin-Like Protein (LLP) of Phytophthora infestans Is Required for Oospore Formation and Plant Infection

Abstract

Loricrin-like protein (LLP) is characterized by a high content of glycine residues and is a major component of plant cell wall. Here, we identified a Phytophthora infestans ortholog of plant LLP, named PiLLP. In P. infestans, PiLLP is strongly expressed in asexual and sexual developmental stages, including in sporangia, zoospores and germinating cysts, and during oospore formation, as well as in the early stages of infection and during hydrogen peroxide stress. Compared with the wild type, the PiLLP-silenced transformants were defective in oospore formation, had slower colony expansion rates, produced less sporangia with lower germination and zoospore-release rates, and were more sensitive to hydrogen peroxide. Moreover, Nile red staining, and PiLLP-red fluorescent protein fusions indicated that PiLLP is involved in oogonia formation. The silenced transformants also had severely diminished virulence levels that could be partially restored with diphenyleneiodium treatments. The analysis of catalase activity showed a decrease of catalase activity in silenced transformants. Thus, PiLLP is important for sexual and asexual reproduction, and is required for oxidative stress tolerance and plant infection.

Transcriptomic and proteomic analysis reveals wall-associated and glucan-degrading proteins with potential roles in Phytophthora infestans sexual spore development

“…Few studies have addressed molecular aspects of the development of sexual spores in oomycetes, in contrast to the more extensive literature on their asexual spores. Several genes influencing oospore formation have been identified in Phytophthora , but they also affect general growth and their impact on oosporogenesis may be secondary [ 61 – 63 ]. One exception comes from the oomycete Py .…”

A proper PiCAT2 level is critical for sporulation, sporangium function, and pathogenicity of Phytophthora infestans

“…The catalase activities of WT, control (CK, i.e., harbouring an empty pGFPN vector), and transformant strains were assayed as described by Guo et al (2017)…”

“…Published RNA‐sequencing data from Ah‐Fong et al () and microarray data from Haas et al () indicated that the PITG_15248 expression level is up‐regulated during asexual reproduction and in the late infection stage. A previous study proved that the silencing of PiLLP in P. infestans inhibits the formation of sporangia and decreases virulence as well as catalase activity (Guo et al , ). These findings suggest that catalase may be important for the asexual reproduction and pathogenesis of oomycetes.…”

“…Many factors, such as nutrient availability, humidity, oxygen levels, and pH, affect the formation of sporangia and the production of zoospores in Phytophthora species (Erwin and Ribeiro, 1996). Previous studies revealed that many genes, including those encoding cell cycle regulators, PiCdc14 (Ah-Fong and Judelson, 2003) and PcSDA1 (Zhu et al, 2016), G protein β and γ subunits (Latijnhouwers and Govers, 2003;van den Hoogen et al, 2018), Myb and MADS-box transcription factors (Xiang and Judelson, 2014;Leesutthiphonchai and Judelson, 2018), and the loricrin-like protein PiLLP (Guo et al, 2017), are associated with the sporulation and pathogenicity of Phytophthora species. However, whether catalase activity affects the sporulation and pathogenicity of Phytophthora species remains unclear.…”

Comparative Transcriptome Analysis Revealed Genes Regulated by Histone Acetylation and Genes Related to Sex Hormone Biosynthesis in Phytophthora infestans

“…The constructed recombinant plasmid was used for overexpressing PITG_10861. The 80787-94L strain was transformed as previously described (Judelson et al, 1991;Mcleod et al, 2008;Guo et al, 2017). All transformants were validated by measuring mycelial PITG_10861 transcript levels in a qRT-PCR assay with specific primers (Supplementary Table S1).…”