Project description:We performed RNA-seq analysis of the root transcriptional response to Fusarium oxysporum f.sp. vasinfectum (FOV) race 4 (FOV4) infection in Gossypium barbadense, also known as Pima cotton. Susceptible Gossypium barbadense inbred lines Pima S-7 (PI 560140) and Pima 3-79 susceptible to Fusarium wilt [Fusarium oxysporum f.sp. vasinfectum (FOV)] race 4 (FOV4), and Pima S-6 (PI 608346) which is resistant to FOV4 infection, were used for the preparation of cDNA libraries and further RNA-seq analyses. An isolate of FOV4 (FOV CA-14) from a naturally infested field in Fresno County in the San Joaquin Valley, California was used in this study.
Project description:Soilborne fungal pathogens cause devastating yield losses, are highly persistent and difficult to control. To culminate infection, these organisms must cope with limited availability of iron. Here we show that the bZIP protein HapX functions as a key regulator of iron homeostasis and virulence in the vascular wilt fungus Fusarium oxysporum. Deletion of hapX does not affect iron uptake, but causes derepression of genes involved in iron-consuming pathways, leading to impaired growth under iron-depleted conditions. F. oxysporum strains lacking HapX are reduced in their capacity to invade and kill tomato plants and immunodepressed mice. The virulence defect of M-NM-^ThapX on tomato plants is exacerbated by coinoculation of roots with a biocontrol strain of Pseudomonas putida, but not with a siderophore-deficient mutant, indicating that HapX contributes to iron competition of F. oxysporum in the tomato rhizosphere. These results establish a conserved role for HapX-mediated iron homeostasis in fungal infection of plants and mammals. Iron dependent gene expression in Fusarium oxysporum wt and M-NM-^ThapX mutant was measured 1 hour after shifting the mycelia to minimal medium with or without 50 M-NM-<M Fe2(SO4)3. Three independent experiments were performed.
