Molecular mechanisms underlying multi-level defense responses of horticultural crops to fungal pathogens

Abstract

The horticultural industry helps to enrich and improve the human diet while contributing to growth of the agricultural economy. However, fungal diseases of horticultural crops frequently occur during pre- and post-harvest periods, reducing yields and crop quality and causing huge economic losses and wasted food. Outcomes of fungal diseases depend on both horticultural plant defense responses and fungal pathogenicity. Plant defense responses are highly sophisticated and are generally divided into preformed and induced defense responses. Preformed defense responses include both physical barriers and phytochemicals, which are the first line of protection. Induced defense responses, which include innate immunity (pattern-triggered immunity and effector-triggered immunity), local defense responses, and systemic defense signaling, are triggered to counterstrike fungal pathogens. Therefore, to develop regulatory strategies for horticultural plant resistance, a comprehensive understanding of defense responses and their underlying mechanisms is critical. Recently, integrated multi-omics analyses, CRISPR-Cas9-based gene editing, high-throughput sequencing, and data mining have greatly contributed to identification and functional determination of novel phytochemicals, regulatory factors, and signaling molecules and their signaling pathways in plant resistance. In this review, research progress on defense responses of horticultural crops to fungal pathogens and novel regulatory strategies to regulate induction of plant resistance are summarized, and then, the problems, challenges, and future research directions are examined.

Biotic stress-induced changes in root exudation confer plant stress tolerance by altering rhizospheric microbial community

“…The molecular mechanisms involved in the regulation of SA and JA crosstalk are not yet very clear. However, according to the studies, NONEXPRESSER OF PATHOGENESIS-RELATED GENES1 (NPR1) acts as a key regulator in SA-induced defence gene expression during the attack of a biotrophic insect, while the SCF COI1 complex helps in the degradation of jasmonate-ZIM domain (JAZ), allowing the activation of JA-mediated defence-related genes (Xu et al, 2022). For example, potato plants infested with herbivores having varied feeding behaviour induce JA signalling during the infestation by necrotrophic insects, while SA signalling is induced in plants during the attack of biotrophic insects (Bari and Jones, 2009;Malacrinò et al, 2021).…”

In Silico Characterization of the Secretome of the Fungal Pathogen Thielaviopsis punctulata, the Causal Agent of Date Palm Black Scorch Disease

“…Effector proteins in the pathogen that are recognized by specific R proteins in the host are called avirulence proteins (Avr) [ 13 ]. The interaction between an R protein and its cognate Avr protein leads to a disease resistance response, often a so-called hypersensitive response (HR), a programmed cell death at the site of infection site by which further growth of the pathogen in the plant is restrained [ 14 , 15 , 16 ]. In response to this, pathogens may overcome ETI by loss-of-function of the avirulence protein or by employing new virulence factors.…”

Arbuscular mycorrhizal fungi enhance disease resistance of Salvia miltiorrhiza to Fusarium wilt

“…AMF induced plant defense response plays an important role in plant disease resistance ( Jung et al., 2012 ). The defense responses of plants can be pre-axisting and induced ( Xu et al., 2022 ). Plant physical structures and phytochemicals provide basic defense against fungal pathogens ( Robert-Seilaniantz et al., 2011 ; Bellincampi et al., 2014 ; Ziv et al., 2018 ).…”