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Schematic model explaining the possible mechanism of CsMLO8-induced PM susceptibility in cucumber. credit: horticultural research (2023). DOI: 10.1093/hour/uhad295
A team from the Cucurbitaceous Vegetable Genetics and Breeding Division at the Institute of Vegetable and Floriculture Research (IVF, CAAS) has made important advances in the molecular mechanisms of powdery mildew (PM) resistance in cucumbers.
The paper is horticultural researchTitled “CsMLO8/11 is required for full susceptibility of cucumber stems to powdery mildew and interacts with CsCRK2 and CsRbohD.”
PM is one of the most devastating diseases threatening cucumber production worldwide. Efficient breeding of new PM-resistant cultivars requires a solid understanding of the molecular mechanisms of PM resistance in cucumber.
Using genome-wide association studies (GWAS), researchers detected a genetic locus, pm-s5.1, that was significantly correlated with PM resistance in cucumber stems. A 1,449 bp insertion into the pm-s5.1 locus in the CsMLO8 coding region enhances stem PM resistance.
Both CsMLO8 and CsMLO11 knockout mutants generated by CRISPR/Cas9 showed improved PM resistance in the stem, hypocotyl, and leaf, and the double mutant mlo8mlo11 showed even stronger resistance.
The researchers found higher accumulation of reactive oxygen species (ROS) in the stems of these mutants.
Protein interaction assays suggested that CsMLO8 and CsMLO11 could physically interact with CsRbohD and CsCRK2, respectively. Furthermore, we showed that CsMLO8 and CsCRK2 competitively interact with the C-terminus of CsRbohD, influencing ROS production via the CsCRK2-CsRbohD module during PM defense.
These findings provide new insights into the understanding of CsMLO proteins during PM defense responses.
For more information:
Shaoyun Dong et al., CsMLO8/11 is required for full susceptibility of cucumber stems to powdery mildew and interacts with CsCRK2 and CsRbohD. horticultural research (2023). DOI: 10.1093/hour/uhad295