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

Abstract

Catalase is present in prokaryotic and eukaryotic organisms and is important for the protective effects of the antioxidant system against free radicals. Many studies have confirmed that catalase is required for the growth, development, and pathogenesis of bacteria, plants, animals, and fungi. However, there has been relatively little research on the catalases in oomycetes, which form an important group of fungus‐like eukaryotes that produce zoosporangia. In this study, we detected two Phytophthora infestans genes encoding catalases, but only PiCAT2 exhibited catalase activity in the sporulation stage and was highly produced during asexual reproduction and in the late infection stage. Compared with the wild‐type strain, the PiCAT2‐silenced P. infestans transformants were more sensitive to abiotic stress, were less pathogenic, and had a lower colony expansion rate and lower PiMPK7, PiVPS1, and PiGPG1 expression levels. In contrast, the PiCAT2‐overexpressed transformants were slightly less sensitive to abiotic stress. Interestingly, increasing and decreasing PiCAT2 expression from the normal level inhibited sporulation, germination, and infectivity, and down‐regulated PiCdc14 expression, but up‐regulated PiSDA1 expression. These results suggest that PiCAT2 is required for P. infestans mycelial growth, asexual reproduction, abiotic stress tolerance, and pathogenicity. However, a proper PiCAT2 level is critical for the formation and normal function of sporangia. Furthermore, PiCAT2 affects P. infestans sporangial formation and function, pathogenicity, and abiotic stress tolerance by regulating the expression of cell cycle‐related genes (PiCdc14 and PiSDA1) and MAPK pathway genes. Our findings provide new insights into catalase functions in eukaryotic pathogens.

Iturin A Extracted From Bacillus subtilis WL-2 Affects Phytophthora infestans via Cell Structure Disruption, Oxidative Stress, and Energy Supply Dysfunction

“…Finally, after coincubation at 20 • C for five days, the inhibitory rates were determined the same above. Marginal P. infestans mycelium disks inhibited by Iturin A (different concentrations) at 20 • C for five days were transferred onto fresh R solid medium (without Iturin A solutions) to recover growth, and an uninhibited mycelium disk was treated as a control (Wang et al, 2020). All the plates were incubated at 20 • C for seven days, and the mycelium relative recovery growth rates were calculated according to the formula below:…”

“…In addition, P. infestans mycelium inhibited by Iturin A (different concentrations) at 20 • C for twelve days was collected with ice-cold sterile water and oscillated to obtain sporangia solution (1 × 10 7 CFU/mL) (Bruisson et al, 2019;Wang et al, 2020). Then, the inhibited sporangia were recovered to release zoospores at 4 • C for 3 h and maintained at 25 • C in the dark for 5 h to complete sporangium direct germination (Hunziker et al, 2015;Bruisson et al, 2019).…”

A Thermotolerant Marine Bacillus amyloliquefaciens S185 Producing Iturin A5 for Antifungal Activity against Fusarium oxysporum f. sp. cubense

“…Optical and fluorescent microscopy revealed morphological alterations in conidia and significant deformities in F. graminearum hyphae treated with iturin A [ 67 ]. Wang et al observed Phytophthora infestans mycelia was damaged and had a rough and swollen shape after iturin A treatment [ 68 ]. Similarly to previous findings, we also observed the major changes and deformations of Foc hyphae after treatment with iturin-A5 produced by S185 ( Figure 8 ).…”

Epigenetic insight into regulatory role of chromatin covalent modifications in lifecycle and virulence of Phytophthora

“…Thus, the authors postulated that Gcn5 has a role in oxidative stress adaptation probably linked to the scavenging of host‐derived ROS (required to evade plant immunity and the development of infection) (Zhao et al ., 2015). The mechanisms to scavenge host‐derived ROS in Phytophthora involve the activity of catalases (Wang et al ., 2020b) and the loricrin‐like protein (LLP) (Guo et al ., 2017). Therefore, it would be interesting to compare the expression and activity of Gcn5 with those of catalases and LLP to better understand how Phytophthora evades host immune responses under epigenetic regulation.…”