CsWRKY10 mediates defence responses to Botrytis cinerea infection in Cucumis sativus

Role of Methyl thiobutyrate to Botrytis cinerea on cucumber

Introduction

Botrytis cinerea is a major agricultural pathogen that causes significant economic Q7 losses worldwide, affecting various crops, including cucumbers. Developing environmentally sustainable control strategies for this pathogen is crucial. Methyl thiobutyrate (MTB), a small organic molecule identified in the volatile organic compounds (VOCs) of biocontrol bacteria, has demonstrated potential in inhibiting B. cinerea both in vitro and in vivo.

Methods

In this study, the efficacy of MTB against cucumber gray mold disease was examined by assessing the in vitro and in vivo activities of MTB against B. cinerea and analyzing the transcriptomic data from MTB-treated cucumber leaves infected with B. cinerea.

Results and discussion

This study shows that a 2 mg/mL solution of MTB inhibits B. cinerea growth by 98.6% in vitro. In vivo, MTB effectively reduces B. cinerea infection in cucumbers, alleviates necrotic damage in leaf tissues, and significantly reduces disease severity. Transcriptomic analysis reveals that MTB activates the plant immune responses by modulating key MAPK cascade signaling genes and upregulating basal defense genes, including chitinase, pectinase, and lignin biosynthesis genes. Furthermore, MTB influences the signaling pathways of salicylic acid (SA), jasmonic acid (JA), and ethylene (ET), resulting in the upregulation of genes such as peroxidase (POD), phenylalanine ammonia-lyase (PAL), lipoxygenase (LOX), and ethyleneresponsive transcription factors (ERFs). These results demonstrate the potential of MTB as an effective biocontrol agent against B. cinerea and provide valuable insights into its underlying mechanisms of action.

Nano-selenium foliar intervention-induced resistance of cucumber to Botrytis cinerea by activating jasmonic acid biosynthesis and regulating phenolic acid and cucurbitacin

PURPOSE AND METHODS

Botrytis cinerea is the primary disease affecting cucumber production. It can be managed by applying pesticides and cultivating disease-resistant cucumber strains. However, challenges, such as drug resistance in pathogenic bacteria and changes in physiological strains, are obstacles in the effective management of B. cinerea. Nano-selenium (Nano-Se) has potential in enhancing crop resistance to biological stress, but the exact mechanism for boosting disease resistance remains unclear. Here, we used metabolomics and transcriptomics to examine how Nano-Se, as an immune activator, induces plant resistance.

RESULT

Compared with the control group, the application of 10.0 mg/L Nano-Se on the cucumber plant's leaf surface resulted in increased levels of chlorophyll, catalase (10.2%), glutathione (326.6%), glutathione peroxidase (52.2%), cucurbitacin (41.40%), and metabolites associated with the phenylpropane synthesis pathway, as well as the total antioxidant capacity (21.3%). Additionally, the expression levels of jasmonic acid (14.8 times) and related synthetic genes, namely LOX (264.1%), LOX4 (224.1%), and AOC2 (309.2%), were up-regulated. A transcription analysis revealed that the CsaV3_4G002860 gene was up-regulated in the KEGG enrichment pathway in response to B. cinerea infection following the 10.0 mg/L Nano-Se treatment.

DISCUSSION

In conclusion, the activation of the phenylpropane biosynthesis and branched-chain fatty acid pathways by Nano-Se promotes the accumulation of jasmonic acid and cucurbitacin in cucumber plants. This enhancement enables the plants to exhibit resistance against B. cinerea infections. Additionally, this study identified a potential candidate gene for cucumber resistance to B. cinerea induced by Nano-Se, thereby laying a theoretical foundation for further research in this area. © 2023 Society of Chemical Industry.

Engineering plant immune circuit: walking to the bright future with a novel toolbox

Plant pathogens destroy crops and cause severe yield losses, leading to an insufficient food supply to sustain the human population. Apart from relying on natural plant immune systems to combat biological agents or waiting for the appropriate evolutionary steps to occur over time, researchers are currently seeking new breakthrough methods to boost disease resistance in plants through genetic engineering. Here, we summarize the past two decades of research in disease resistance engineering against an assortment of pathogens through modifying the plant immune components (internal and external) with several biotechnological techniques. We also discuss potential strategies and provide perspectives on engineering plant immune systems for enhanced pathogen resistance and plant fitness.

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

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 postharvest 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.