Cherry leaf spot, caused by Blumeriella jaapii, is one of the most widespread and economically damaging diseases of sour and sweet cherries. The disease leads to early leaf drop, reduces photosynthesis and yield, and compromises tree health over multiple growing seasons. Conventional management relies heavily on fungicide applications, which face increasing regulatory restrictions and environmental concerns. While partial resistance has been observed across some cherry varieties, the underlying genetic mechanisms have been poorly understood, largely due to the complex polyploid nature of the sour cherry genome. Based on these challenges, there is a need to conduct deeper research to clarify the genetic control of disease resistance.
Researchers from the Julius Kühn Institute have published (DOI: 10.1093/hr/uhaf035) new findings in Horticulture Research on May 1, 2025, revealing distinct genetic regions in sour cherry that control resistance and susceptibility to cherry leaf spot. Using a high-density SNP array and field disease evaluations in a biparental population, the team identified two key QTLs located on Chromosome 1 that influence response to infection. The study clarifies how resistance is inherited and provides breeders with molecular markers to support targeted selection of resistant cultivars.
The team established an F1 population from a cross between a highly susceptible cultivar (‘Schattenmorelle’) and a more tolerant cultivar (‘Pc 2’). Both parents and 202 progeny individuals were genotyped using the RosBREED 6+9K SNP array and SSR markers. Disease severity was then evaluated in both controlled inoculation trials and natural field infection across two growing seasons.
Two major QTLs located on the Prunus fruticosa subgenome of Chromosome 1 were consistently detected across years. The first QTL (named CLSR 1f) was associated with reduced disease severity and originated from the tolerant parent ‘Pc 2’. The second QTL (CLSS 1f) was linked to increased susceptibility and derived from ‘Schattenmorelle’. Together, the loci explained a substantial proportion of phenotypic variation, confirming a two-gene resistance model. Importantly, this resistance mechanism was found to be independent of the previously known QTL CLSR G4 derived from Prunus canescens, revealing that sour cherry carries its own distinct resistance source. Within the mapped regions, researchers also identified clusters of candidate genes encoding NLR and receptor-like proteins, indicating that immune signaling pathways may drive resistance.
“Our findings provide a clearer genetic explanation for why some sour cherry lines remain healthy while others suffer severe defoliation, even when they share similar ancestry,” the research team stated. “By distinguishing resistance and susceptibility loci, breeders now have precise molecular targets to guide parent selection and accelerate the development of new cultivars. Importantly, this research also broadens our understanding of plant immunity within polyploid fruit crops, where complex genome structures often mask key genetic mechanisms.”
This work will directly support breeding programs seeking to reduce reliance on fungicides and improve orchard sustainability. Molecular markers linked to CLSR 1f and CLSS 1f can now be used to screen seedlings at early stages, eliminating the need for multiyear field disease evaluations. Identifying resistance controlled by sour cherry’s own genetic background also offers strategic advantages, enabling breeders to avoid unwanted traits sometimes introduced through interspecies hybridization. Ultimately, these insights may lead to the release of new high-yielding, disease-resilient sour cherry cultivars that lower production costs and support environmentally responsible fruit production.
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References
DOI
10.1093/hr/uhaf035
Original Source URL
https://doi.org/10.1093/hr/uhaf035
About Horticulture Research
Horticulture Research is an open access journal of Nanjing Agricultural University and ranked number one in the Horticulture category of the Journal Citation Reports ™ from Clarivate, 2023. The journal is committed to publishing original research articles, reviews, perspectives, comments, correspondence articles and letters to the editor related to all major horticultural plants and disciplines, including biotechnology, breeding, cellular and molecular biology, evolution, genetics, inter-species interactions, physiology, and the origination and domestication of crops.