Secreted in Xylem (SIX) gene SIX9 is highly conserved in Fusarium oxysporum f. sp. vasinfectum race 4

Authors: Jobe, Timothy; URNER, MICHAEL - California State University; Ulloa, Mauricio; Broders, Kirk; HUTMACHER, ROBERT - University Of California, Davis; ELLIS, MARGARET - California State University

Submitted to: PhytoFrontiers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/26/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary: Many fungal pathogens produce small, infection-dependent proteins called ‘secreted in xylem’ (SIX) proteins. These proteins are secreted into the plant during the infection process and are thought to increase virulence or disease. In this study, a collection of fungal strains or isolates composed primarily of different fungi that cause Fusarium wilt (FOV) in cotton - one of the most severe diseases of cotton, was evaluated for the presence or absence of these protein-genes. Our results show that the most virulent fungus in the U.S., FOV race 4 as well as a fungus from China, FOV race 7 share a common gene not found in less virulent strains. This gene is also absent in other fungi that infect cotton in North America such as FOV race 1. Our goal is to establish gene-effector profiles that differentiate FOV races and link FOV race definitions to genes involved in the infection process. This will allow the development of tools for rapid identification of novel isolates that may pose a threat to cotton production and could enable race specific FOV quantification in infected plants and soils. These data will be of particular interest to scientists working in the fields of cotton disease, cotton breeding, and Fusarium genetics.

Technical Abstract: Many Fusarium oxysporum formae speciales produce small, infection-dependent effector proteins called ‘secreted in xylem’ (SIX) proteins. As the name implies, these proteins are secreted into the xylem of a plant during the infection process and are thought to promote virulence. In this study, a collection of Fusarium oxysporum isolates composed primarily of different Fusarium oxysporum f. sp. vasinfectum (FOV) races, was screened for the presence or absence of fourteen SIX effector genes (SIX1-SIX14). Our results show that the most virulent FOV races, FOV4 & FOV7, share a common SIX effector – SIX9. This effector is largely absent in other races of FOV in North America making SIX9 a potential target for rapid detection of these highly virulent FOV strains and enabling race specific FOV quantification in infected cotton plants.