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Poster

Session: Session 2 Presenting Authors at Posters (Evens)

P-074 - The common bean I gene of resistance to Potyviruses: molecular mechanisms and range of action

Thursday, July 17, 2025
13:30 - 15:15  
Location: Confex Hall 3
Crop resistance genetics and genomics

Common bean (Phaseolus vulgaris) is the most important grain legume for direct human consumption worldwide. Its production is notably limited by viral pathogens such as bean common mosaic virus (BCMV) and bean common mosaic necrosis virus (BCMNV). Discovered in 1934 and later characterized as a dominant gene, the I gene remains hitherto the only dominant resistant (R) gene against these two potyviruses identified in P. vulgaris genetic resources. Despite being widely used in bean breeding programs worldwide for decades, the I gene has not been overcome. It is also a broad-spectrum R gene since resistance to at least 8 other viruses has been mapped at the I cluster. Despite the agronomic interest of this antiviral R gene, the complexity of the I cluster presenting many NLR sequences, combined with the suppression of recombination, has annihilated the attempts to identify the I gene using a map-based cloning strategy. We recently isolated the I gene thanks to two independent mutants. The corresponding Avr protein of BCMNV, NIa-Pro, was identified by transiently expressing its 11 encoded proteins in bean leaves. NIa-Pro is a constrained Potyvirus protease, which might be a hint to the I gene durability. We are currently evaluating the spectrum of recognition of the I gene and examining the mechanism of recognition of BCMNV NIa-Pro, by performing agroinfiltration of NIa-Pro from a large panel of 30 different Potyvirus species as well as “dead-protease” mutated forms of NIa-Pro.