Analysis of the Oxidative Burst and Its Relevant Signaling Pathways in Leptosphaeria maculans—Brassica napus Pathosystem

Abstract

An oxidative burst is an early response of plants to various biotic/abiotic stresses. In plant-microbe interactions, the plant body can induce oxidative burst to activate various defense mechanisms to combat phytopathogens. A localized oxidative burst is also one of the typical behaviors during hypersensitive response (HR) caused by gene-for-gene interaction. In this study, the occurrence of oxidative burst and its signaling pathways was studied from different levels of disease severity (i.e., susceptible, intermediate, and resistant) in the B. napus–L. maculans pathosystem. Canola cotyledons with distinct levels of resistance exhibited differential regulation of the genes involved in reactive oxygen species (ROS) accumulation and responses. Histochemical assays were carried out to understand the patterns of H2O2 accumulation and cell death. Intermediate and resistant genotypes exhibited earlier accumulation of H2O2 and emergence of cell death around the inoculation origins. The observations also suggested that the cotyledons with stronger resistance were able to form a protective region of intensive oxidative bursts between the areas with and without hyphal intrusions to block further fungal advancement to the uninfected regions. The qPCR analysis suggested that different onset patterns of some marker genes in ROS accumulation/programmed cell death (PCD) such as RBOHD, MPK3 were associated with distinct levels of resistance from B. napus cultivars against L. maculans. The observations and datasets from this article indicated the distinct differences in ROS-related cellular behaviors and signaling between compatible and incompatible interactions.

Meiotic recombination in Leptosphaeria maculans favours the rise of transgressive isolates adapted to a nonhost species, Brassica carinata

“…In adapted interactions, contact between hyphae and stomates were observed, suggesting penetration of B. carinata stomates, as is the case for adapted isolates on B. napus . Yang and Fernando (2021) performed microscopic analyses between various isolates of L. maculans and different genotypes of B. napus, showing that an adapted interaction is associated with hyphal growth, colonization of intercellular spaces, and pycnidia formation, consistent with previous analyses (Hammond et al ., 1985; Li et al ., 2008). In contrast, neither pycnidia formation nor extensive necrosis was observed in the non-adapted interactions, as in an incompatible interaction.…”

Molecular Mechanisms of the Stripe Rust Interaction with Resistant and Susceptible Wheat Genotypes

“…Although the number of such genes was greater in the resistant plant background, three out of five stress-related genes upregulated in the susceptible host, PSTG_20181, PSTG_12250, and PSTG_10795, were also related to oxidative stress response. The oxidative burst is widely reported as a basal plant defense against pathogens [ 51 , 52 ]. It is one of the fastest and the most ubiquitous PAMP-recognition-triggered responses.…”

Knockout of mitogen-activated protein kinase 3 causes barley root resistance against Fusarium graminearum

“…The ROS generated and released during infection can affect both counterparts, the host and the microbe (Desmond et al ., 2008; Yang and Fernando, 2021). ROS are indispensable for the activation of plant defense responses as a signaling component (Lee et al ., 2020) or they can cause peroxidation of lipids, oxidation of proteins, damage to nucleic acids, enzyme inhibition, and activation of PCD pathway during hypersensitive response (Camagna and Takemoto, 2018), thus leading to the inhibition of biotrophic pathogens.…”