AI and Natural Resistance Combine to Fight Citrus Greening Disease

A team led by Prof. YE Jian at the Institute of Microbiology of the Chinese Academy of Sciences has identified the first mechanism of citrus resistance to citrus greening disease (HLB), also known as huanglongbing. The study details the development of antimicrobial peptides using artificial intelligence (AI) as a promising therapeutic approach.

HLB, triggered by the bacterium Candidatus Liberibacter asiaticus (CLas) and spread by the Asian citrus psyllid, has devastated citrus crops worldwide, causing billions in annual losses. The disease impacts over 50 countries across Asia, Africa, the Americas, and Europe.

Discovery of Resistance Pathway

Researchers identified a key resistance pathway involving the transcription factor MYC2 and its interacting E3 ligase, PUB21. They discovered PUB21 paralogs in curry leaf and Sichuan pepper plants that encode a dominant-negative form of PUB21 (PUB21DN), which suppresses PUB21 activity.

This suppression stabilizes the MYC2 protein, enhancing defense pathways and antibacterial metabolite production, thus conferring immunity to HLB. Transgenic citrus plants engineered to overexpress PUB21DN showed increased resistance to the disease.

AI-Driven Peptide Development

The team used AI-driven screening technology to stabilize MYC2 by inhibiting PUB21 activity. This led to the identification of anti-proteolysis peptides (APPs), including APP3-14, which demonstrated up to 80% control efficiency in field trials.

APP3-14 effectively controlled the HLB-causing pathogen CLas and disrupted disease transmission. This breakthrough offers a dual benefit: eco-friendly bio-pesticides and a strategy to combat uncultivable pathogens through targeted protein stabilization.

Potential Applications

Beyond HLB, this strategy could address other plant diseases caused by difficult-to-culture pathogens, such as maize rust fungus and Olive Quick Decline Syndrome (OQDS). By targeting pathogen effectors and stabilizing host immune proteins, this study paves the way for innovative disease resistance solutions in various crops, offering new hope for global agricultural sustainability.