Plant susceptible responses: the underestimated side of plant–pathogen interactions

Abstract

Plant susceptibility to pathogens is usually considered from the perspective of the loss of resistance. However, susceptibility cannot be equated with plant passivity since active host cooperation may be required for the pathogen to propagate and cause disease. This cooperation consists of the induction of reactions called susceptible responses that transform a plant from an autonomous biological unit into a component of a pathosystem. Induced susceptibility is scarcely discussed in the literature (at least compared to induced resistance) although this phenomenon has a fundamental impact on plant–pathogen interactions and disease progression. This review aims to summarize current knowledge on plant susceptible responses and their regulation. We highlight two main categories of susceptible responses according to their consequences and indicate the relevance of susceptible response‐related studies to agricultural practice. We hope that this review will generate interest in this underestimated aspect of plant–pathogen interactions.

Gene expression and phytohormone levels in the asymptomatic and symptomatic phases of infection in potato tubers inoculated with Dickeya solani

“…The induced host pectinases may promote cell wall remodeling [ 62 ], which may increase the amount of defense-activating pectic fragments to amplify the DAMP response. On the other hand, plant pectinases and cell-wall modification have been suggested to be susceptibility responses that are induced by virulent plant pathogens to promote symptoms in their susceptible host plant [ 63 ].…”

“…The function of sugar transporters may be important for the plant’s ability to mount an efficient defense, or it may be related to the ability of the bacteria to modulate sugar efflux of their host for their own benefit [ 67 ]. Redistribution of sugars and changes in the transport of water and nutrients have been identified as susceptibility responses affected by pathogens to create a suitable environment for pathogenesis [ 63 ].…”

Structure-Functional Characteristics of the Svx Protein—The Virulence Factor of the Phytopathogenic Bacterium Pectobacterium atrosepticum

“…Moreover, some extensins (designated as LRX), containing an additional N-terminal domain composed of leucine-rich repeats (LRR), are considered important sensors that trace the state of PCW and transmit the signals via partner proteins [56,57]. Thus, breaking down or modifying extensins may not only weaken PCW but also influence the signaling processes of the host plant, leading to the repression of defense reactions or the induction of susceptible responses [58].…”

Seed Transmission of Pathogens: Non-Canonical Immune Response in Arabidopsis Germinating Seeds Compared to Early Seedlings against the Necrotrophic Fungus Alternaria brassicicola

“…Therefore, the GO analysis of the DEGs provide evidence that A. brassicicola seed infection caused increased expression of genes described to contribute to defense pathways, and on the other hand reduced the expression of genes involved in metabolic activity, growth and photosynthesis. Beyond the noted absence of inducing the JA pathway in germinating seeds, the identified responding pathways (Figure 2A), such as the induction of response to wounding and to catabolic process in seedlings and the repression of starch metabolism and cell wall biogenesis (Figure 2B) suggested that A. brassicicola in part would hijack the seed and seedling response to facilitate its colonization [43].…”