Registration of six lettuce breeding lines with resistance to Fusarium wilt race 1

Abstract Lettuce ( Lactuca sativa L.) is a billion‐dollar industry in the United States, with California and Arizona producing over 90%. Fusarium wilt (FW), caused by Fusarium oxysporum f. sp. lactucae (Fol) race 1, is a major disease of lettuce worldwide. Genetic resistance is the most sustainable practice for FW control. With the objective of combatting this challenge, we report the registration of six breeding lines: 15631 (Reg. no. GP‐12, PI 691904), 15632 (Reg. no. GP‐13, PI 691905), 15633 (Reg. no. GP‐14, PI 691906), 15634 (Reg. no. GP‐15, PI 691907), 15669 (Reg. no. GP‐16, PI 691908), and 15670 (Reg. no. GP‐17, PI 691909) with resistance to FW race 1. These were developed and released by the USDA‐ARS from a cross between ‘King Louie’ (romaine type; resistant to FW race 1) and ‘Autumn Gold’ (crisphead type; susceptible to FW race 1). They were selected using a pedigree selection breeding method through greenhouse and field evaluations. Disease severity was assessed using standardized visual rating scales, for example, 1, no disease to 4, dead plant, with the releases exhibiting significantly lower FW severity and incidence compared with susceptible checks. These breeding lines have shown stable and uniform resistance to FW race 1 in multiple trials and offer an essential genetic resource for lettuce breeders and seed companies. Preliminary greenhouse results suggest they are also resistant to novel pathogenic variants that were recently detected in California. These lines are available for research and to incorporate FW race 1 resistance into elite lines, contributing to sustainable lettuce production in affected regions.