Gummy Stem Blight Resistance in Cucurbit Crops

Gummy stem blight (GSB) is a pervasive fungal disease affecting cucurbit species worldwide, caused by a complex of Stagonosporopsis (syn. Didymella) pathogens. The disease manifests as water-soaked leaf lesions, stem cankers exuding amber gummy droplets and fruit rot, leading to severe yield losses in cucumber, melon, watermelon and squash. Reliance on fungicides is increasingly challenged by the emergence of resistant pathogen strains and environmental concerns. Consequently, the development of genetic resistance in host crops has become a primary strategy for sustainable control. Recent efforts have focused on elucidating the molecular basis of resistance through quantitative trait locus (QTL) mapping, fine‐scale gene cloning and candidate gene validation, alongside genome and transcriptome analyses of both host and pathogen. These studies reveal that resistance often involves multiple loci, including NBS-LRR genes, receptor-like kinases and transcriptional regulators, which mediate early detection of infection and activation of defence networks. Marker‐assisted selection (MAS) and genomic selection approaches are now being deployed to combine resistance alleles, with the aim of delivering broad-spectrum, durable resistance in commercial cultivars.

Research from Nature Portfolio

A comprehensive genome assembly of Stagonosporopsis cucurbitacearum has provided a high-resolution map of the pathogen’s gene content, revealing nearly 1,000 secreted proteins and a rich complement of carbohydrate-active enzymes implicated in host cell wall degradation. Comparative transcriptome profiling before and after infection identified differentially expressed effector candidates, including small secreted proteins and ATP-binding cassette transporters, that likely orchestrate fungal colonisation and evasion of host defences. Integration of pathogenicity gene catalogues with host interaction databases has highlighted conserved virulence factors shared with related necrotrophic fungi. This resource establishes a foundation for reverse-genetics studies and guides the development of novel control measures targeting key pathogenicity determinants.

Gummy Stem Blight Resistance in Cucurbit Crops publication trend

The graph below shows the total number of articles in gummy stem blight resistance in cucurbit crops across all publications each year (not limited to Nature Index journals).

Technical terms

Quantitative Trait Locus (QTL): A region of the genome statistically linked to variation in a quantitative trait, such as resistance level.

Appressorium: A specialised fungal infection structure that adheres to and penetrates host surfaces.

Nucleotide-binding site leucine-rich repeat (NBS-LRR): A class of plant immune receptors that detect pathogen effectors and trigger defence responses.

Reactive oxygen species (ROS): Highly reactive molecules, including hydrogen peroxide, produced by plants as an early defence signal against pathogens.

References

1. Gummy stem blight: One disease, three pathogens. Molecular Plant Pathology (2023).
2. Genome-scale analyses and characteristics of putative pathogenicity genes of Stagonosporopsis cucurbitacearum, a pumpkin gummy stem blight fungus. Scientific Reports (2020).
3. Infection Biology of Stagonosporopsis cucurbitacearum in Watermelon and Defence Responses in the Host. Agriculture (2024).
4. Fine mapping a quantitative trait locus underlying seedling resistance to gummy stem blight using a residual heterozygous lines-derived strategy in cucumber. Frontiers in Plant Science (2022).