From pathogen effectors to plant enhancers - Harpin proteins as novel biostimulants: A review.
Patoliya J, Thaker K, Kumar P, Jain N, Joshi R
Plant Signaling
Tomatoes, wheat, and other crops you eat could soon be grown with less pesticide and more resilience to drought, because a protein borrowed from plant-infecting bacteria has been shown to naturally activate a plant's own defenses and growth systems.
Bacteria that infect plants produce proteins called harpins as part of their attack toolkit. Scientists discovered that when these same proteins are sprayed onto plants from the outside — rather than injected by a pathogen — the plants respond by ramping up their immune systems and growing better. This review pulls together 30 years of research to explain how that surprising flip works and how it could be used to grow healthier crops with fewer chemicals.
Key Findings
Harpins activate salicylic acid-based systemic acquired resistance (SAR), a whole-plant immune response, as well as multiple other hormone signaling networks including ethylene, jasmonic acid, and abscisic acid.
Exogenous harpin application improves growth, yield, and crop quality across diverse plant species, though results show some inconsistency under real-world field conditions.
Phylogenetic analysis reveals that harpins form a superfamily with distinct ancestral core lineages and more recently diversified branches, clarifying their evolutionary origins and diversity.
chevron_right Technical Summary
Harpin proteins, originally known as bacterial weapons against plants, turn out to be powerful plant boosters when applied externally — strengthening immunity, improving stress tolerance, and increasing crop yields across many species.
Abstract Preview
Harpin proteins were originally identified as hypersensitive response-eliciting factors produced by bacterial plant pathogens. Over the past three decades, however, accumulating evidence has reveal...
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