Peach (Prunus persica) is a widely cultivated stone fruit valued for its flavor, economic importance, and ornamental appeal. However, bacterial spot (BS) disease can cause leaf perforations and necrotic lesions on fruit, directly affecting tree health and marketability. Plant infection often triggers bursts of reactive oxygen species (ROS), which can help signal defense but may also damage cells when excessive. Specialized metabolites, including lignin, flavonols, anthocyanins, and proanthocyanidins (PAs), are increasingly recognized as important components of plant immunity. Yet the molecular basis of PA-mediated resistance tobacterial spot (BS) disease in peach has remained poorly understood. Due to these challenges, a deeper investigation into how peach controls PA accumulation during bacterial infection was needed.
Researchers from the State Key Laboratory of Plant Diversity and Specialty Crops, Wuhan Botanical Garden, Chinese Academy of Sciences; University of Chinese Academy of Sciences; Huazhong Agricultural University; and Huanggang Normal University reported (DOI: 10.1093/hr/uhag032) the findings in Horticulture Research on 30 January 2026. The study used pathogen inoculation, transcriptome analysis, transient gene expression, biochemical assays, and protein interaction tests to define how the PpPUB23–PpMYB123 regulatory module controls PA-based defense.
The study first showed that Xap inoculation caused strong PA accumulation in both peach leaves and fruits. Transcriptome profiling revealed activation of PA biosynthetic genes shortly after infection, while 4-dimethylaminocinnamaldehyde (DMACA) staining and quantitative assays confirmed elevated PA levels in infected tissues. Applying exogenous PAs reduced lesion size in tobacco leaves, peach leaves, and peach fruits, lowered hydrogen peroxide (H₂O₂) accumulation, and directly inhibited pathogen growth in vitro. The researchers then identified PpMYB123 as a key infection-responsive regulator. Overexpressing PpMYB123 increased PA levels, activated PpANR and PpLAR, reduced H₂O₂ accumulation, and alleviated disease symptoms, whereas silencing PpMYB123 weakened PA production and aggravated tissue damage. Yeast one-hybrid assay and electrophoretic mobility shift assay (EMSA) confirmed that PpMYB123 directly binds to the promoters of PpANR and PpLAR, turning on the PA biosynthetic pathway during bacterial challenge.
The authors said the findings reveal a defense system in which peach plants do more than passively respond to infection. Instead, they redirect metabolism toward compounds that protect tissues from both oxidative injury and bacterial expansion. They said PpPUB23 acts as a molecular brake on PpMYB123 under normal conditions by promoting its ubiquitin-dependent degradation. When infection occurs, PpPUB23 expression is suppressed, allowing PpMYB123 to accumulate and drive PA biosynthesis. This switch helps peach tissues limit cell damage while restricting pathogen growth.
These findings point to practical targets for improving peach resistance to BS disease. Because PAs provide dual protection by scavenging excess ROS and suppressing Xap growth, enhancing PA biosynthesis could support future breeding strategies for healthier trees and higher-quality fruit. The PpPUB23–PpMYB123 module may be useful for marker-assisted selection, molecular breeding, or biotechnology-based improvement. More broadly, the study adds to growing evidence that specialized metabolites are not merely byproducts of plant metabolism but active defense tools. Understanding these pathways may help develop more sustainable disease-management strategies with reduced dependence on chemical control.
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References
DOI
10.1093/hr/uhag032
Original Source URL
https://doi.org/10.1093/hr/uhag032
Funding information
This project was supported by funds received from National Natural Science Foundation of China (32302497), the China Agriculture Research System (grant CARS-30) and the Wuhan Botanical Garden Scientific Research Support Project (E3559901).
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.