Molecular Genetics of Powdery Mildew Resistance in Cucurbits

Powdery mildew, caused predominantly by the obligate biotrophic fungi Podosphaera xanthii and Golovinomyces orontii, represents a major threat to cucurbit production worldwide, affecting cucumber, melon, squash, pumpkin, watermelon and related species. Molecular genetic studies have revealed that resistance often arises from both race-nonspecific quantitative trait loci and race-specific genes, such as loss-of-function alleles at Mildew Locus O (MLO) homologues. Broad-spectrum resistance also involves complex regulatory networks encompassing reactive oxygen species (ROS) signalling, salicylic acid (SA) and jasmonic acid (JA) pathways, flavonoid and phenylpropanoid biosynthesis, polyamine metabolism and cell-wall fortification. Genome-wide association studies and QTL mapping have identified resistance loci on multiple chromosomes in melon and cucumber, while introgression of major genes from wild relatives has yielded commercial cultivars with enhanced tolerance. Modern approaches including CRISPR/Cas9-mediated gene editing, transcriptome and proteome profiling, and marker-assisted selection are underpinning the dissection of resistance mechanisms and accelerating the deployment of resistant germplasm. Such interdisciplinary efforts have global significance for sustainable cucurbit agriculture and reduction in fungicide usage.

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Molecular Genetics of Powdery Mildew Resistance in Cucurbits publication trend

The graph below shows the total number of articles in molecular genetics of powdery mildew resistance in cucurbits across all publications each year (not limited to Nature Index journals).

Technical terms

Obligate biotroph: A pathogen that requires living host tissue to complete its life cycle.

MLO (Mildew Locus O) genes: A family of plant genes whose loss-of-function mutations confer broad-spectrum powdery mildew resistance.

Reactive oxygen species (ROS): Chemically reactive molecules derived from oxygen that play signalling roles in plant defence.

Phenylpropanoid pathway: A metabolic route generating lignin, flavonoids and other phenolic compounds involved in cell-wall reinforcement and defence.

Polyamines: Small aliphatic amines (e.g., putrescine, spermine) implicated in stress responses and defence regulation.

CRISPR/Cas9: A genome-editing technology used to generate targeted gene knockouts or modifications.

References

1. Nano-selenium enhances melon resistance to Podosphaera xanthii by enhancing the antioxidant capacity and promoting alterations in the polyamine, phenylpropanoid and hormone signaling pathways. Journal of Nanobiotechnology (2023).
2. CsMLO8/11 are required for full susceptibility of cucumber stem to powdery mildew and interact with CsCRK2 and CsRbohD. Horticulture Research (2023).
3. Status, Gaps and Perspectives of Powdery Mildew Resistance Research and Breeding in Cucurbits. Critical Reviews in Plant Sciences (2024).