Location: Plant Stress and Germplasm Development Research
Project Number: 3096-21000-023-004-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Jun 1, 2023
End Date: Sep 30, 2025
Objective:
1. Identify Fusarium wilt race 4 (FOV4) biotypes or populations in infested soils from California and Texas cotton production fields.
2. Use representative FOV races for phenotypic evaluation of selected germplasm.
Approach:
Fusarium wilt of cotton, caused by Fusarium oxysporum f. sp. vasinfectum (FOV), is one of the most important diseases in cotton producing regions throughout the world, causing significant economic losses to cotton farmers. This proposed research is part of a collaborative effort by USDA-ARS, the National Plant Disease Recovery System (NPDRS), and University cooperators for combating FOV, a serious economic threat for sustainable cotton production in the USA. Part of this research work will be conducted at California State University, Fresno (Fresno State) and will be focused on identifying the most prevalent FOV races and other pathogens in infested fields and use these representative identified FOV races, biotypes, or populations for phenotypic evaluation of selected germplasm. Candidate germplasm will be evaluated through artificial soil inoculation in the greenhouse following an established protocol. Collected FOV isolates will be screened using FOV4 race-specific primers. Also, we will further genotype a set of representative FOV isolates using DNA sequencing of several genes (EF-1a, PHO, and BT). In addition, whole genome sequence will be performed at the USDA-ARS, Lubbock, TX for selected FOV populations. After obtaining high-quality whole genome sequences of selected FOV isolates, we will compare the genomes using a suite of tools tailored to intra-species genome comparisons. The goal of this work is to identify key similarities between the FOV4 genomes and to identify common differences between the FOV4 and other races of FOV. So far, based on preliminary data collected in several fields, there seems to be that other FOV races or biotypes may be interacting with FOV4 to increase disease incidence. This interaction may be able to break the resistance found in some cultivars with high levels of resistance to FOV4. Promising germplasm will also be screened, and evaluation methods will be like those previously described by research done in California. Host-plant resistance is the only cost-effective long-term solution to address the problem of FOV, but its use is seriously impeded by the narrow genetic base of Upland cotton. There is the need to identify and develop Upland cotton resistant/tolerant to FOV4 to make sure that we are prepared to handle its potential threat and spread into other cotton-growing areas in the USA.
