Project Number: 3096-21000-022-021-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Mar 8, 2019
End Date: May 30, 2022
1. To evaluate selected Uzbek germplasm and cotton substitution lines with alien introgression for resistance to FOV race 4 (FOV4) under greenhouse conditions. When possible, this greenhouse screening will be expanded to FOV4 infested fields in NM. 2. To assess the extent of root colonization by FOV4 in genotypes of cotton varying in resistance/tolerance
This proposed research is part of a collaborative effort by USDA-ARS and University cooperators in the USA for combating fusarium wilt caused by Fusarium oxysporum f. sp. Vasinfectum (FOV) a serious economic threat for sustainable cotton production in the USA and Uzbekistan. The work to be conducted at NM State University will be focused on evaluating selected cotton genotypes for resistance/tolerance to FOV race 4 (FOV4) and on assessing root infection by FOV4. Candidate Uzbek germplasm and cotton substitution lines with alien introgression will be evaluated through artificial soil inoculation in the greenhouse following an established protocol. A FOV4 isolate will be grown in Czapek Dox broth for 4-5 days on a rotary shaker. Conidia will be collected from the liquid culture, and soil will be inoculated at a concentration of 103 conidia per gram of soil. Seeds will be planted in the infested soil and monitored for germination and disease development. Disease incidence/severity will be recorded for each genotype. In addition, through the growing season infected plant tissue will be collected from known infested FOV4 fields, and infected tissue will be assessed for pathogen identification, including FOV4. The extent of root colonization by FOV4 will be determined based on the frequency of isolation of FOV4 per length of root (in cm) as previously established at our laboratory. Plant roots will be rinsed in running tap water to remove any remaining soil. Taproots will be severed from each plant, placed in 0.5% tergitol for 2 minutes, immersed in 0.5% sodium hypochlorite for 3 minutes, rinsed in sterile distilled water, and air dried. Then the taproots will be cut into 0.5-cm pieces and placed on acidified potato dextrose agar (APDA) at room temperature (22-25oC). The frequency of isolation of FOV4 will be determined as the percentage of root pieces yielding colonies of FOV4. The extent of root colonization will be also determined based on colony-forming units (CFU) per length of root (in cm). Taproots will be collected as described above and milled. A suspension of the milled root tissue will be prepared, serially diluted, and plated on APDA medium. For the last decade, FOV4 has spread from fields in northern California to fields in the southern part of the state where seed cotton is produced. In addition, in 2017, this serious soil and seedborne cotton fungal pathogen was reported to be found in Texas and threatens Upland (Gossypium hirsutum L.) cotton production with potentially significant yield losses. There is the need to identify and develop resistant/tolerant Upland cotton to FOV4 to make sure that we are prepared to handle its potential threat and spread into other cotton-growing areas in the USA.