What is it about?
Pepper is one of the most widely consumed vegetables worldwide, but each year it suffers major yield losses from anthracnose, a devastating fungal disease. Globally, farmers struggle with severe damage from this disease, which can wipe out a significant share of production. To combat it, researchers have worked for more than a decade. In 2012, the first anthracnose-resistant pepper cultivar was developed through crossbreeding, and subsequent studies identified key resistance genes. Scientists have now discovered how pepper plants defend themselves throughout the entire plant, not just where the infection begins. When anthracnose attacks, a resistance protein known as CbAR9 joins forces with a protein called CbSAHH to produce a mobile messenger, methyl salicylate (MeSA). This messenger spreads from the infected area to healthy tissues, warning them to activate their defenses in advance. For the first time, researchers have provided clear evidence of a mobile immune signaling pathway in pepper plants, demonstrating that the immune receptor CbAR9 interacts with SAHH, an enzyme of the methionine cycle, to drive MeSA production and coordinate defense responses throughout the entire plant. This finding, published in the renowned international journal Plant Physiology, could pave the way for developing new disease-resistant pepper cultivars and inspire strategies to protect other crops from devastating diseases.
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Why is it important?
This study is important because it uncovers, for the first time in pepper, how systemic resistance is triggered through specific protein–protein interactions. The work also shows that immune receptors are more than simple pathogen detectors — they act as active controllers that adjust plant metabolism to switch on immunity throughout the plant. These discoveries could provide useful molecular targets for developing new disease-resistant pepper varieties and for designing MeSA-based immune boosters.
Perspectives
Working on this study was a rewarding journey because it allowed us to uncover how pepper plants control a whole-body immune response against a devastating fungal disease. As someone who has long been fascinated by the hidden logic of plant immunity, I found it particularly exciting to see how an immune receptor and a metabolic enzyme form a functional partnership to mobilize systemic resistance. For me, the most meaningful aspect of this work is that it bridges fundamental molecular biology with practical opportunities for agriculture. I hope these findings not only contribute to breeding stronger, disease-resistant pepper cultivars but also inspire broader strategies to protect other crops from the growing challenges of plant diseases under climate change.
Seungmin Son
National Institute of Agricultural Sciences, Rural Development Administration
Read the Original
This page is a summary of: The NLR protein CbAR9 and the hydrolase CbSAHH form a module driving systemic acquired resistance against Colletotrichum in pepper, PLANT PHYSIOLOGY, June 2025, Oxford University Press (OUP),
DOI: 10.1093/plphys/kiaf288.
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