Identification of a novel effector gene and its functional tradeoff in Fusarium oxysporum f. sp. cepae that infects Welsh onion

Fusarium oxysporum f. sp. cepae (Foc) is a causal agent of Fusarium wilt in Welsh onion, leading to tremendous production loss. However, pathogenicity-related factors in Welsh onion-infecting Foc have not been elucidated. Here, we screened F. oxysporum f. sp. Cepae Effector candidate Protein (Cep) from next-generation sequencing data of Welsh onion-infecting Foc. Intriguingly, most of the Cep genes (including SIX2 and SIX9) expressed during infection were located on a 3-Mb-sized chromosome in Welsh onion-infecting Foc. Further investigation of the 3-Mb-sized chromosome clarified that the Cep28 is related to virulence, pigmentation, vegetative growth, and stress tolerance and has a functional tradeoff between virulence and vegetative growth.