Genetic Mapping for Resistance to Fusarium Wilt in Two Introgressed Populations of Upland Cotton

Fusarium wilt (FW) caused by the soil-borne fungus Fusarium oxysporum f. sp. vasinfectum race 4 causes high cotton seedling mortality under field conditions in the west and southwest US Cotton Belt. The objectives of this study were to identify quantitative trait loci (QTL) in two introgressed Upland cotton (Gossypium hirsutum) populations using an artificial inoculation and screening method. The two populations (IL-122 with 120 introgressed lines and BIL-193 with 180 backcross inbred lines) were derived from backcrossing the same recurrent Upland parent (FOV4 resistant) to two different interspecific hybrids each with a different G. barbadense parent (FOV4 susceptible). The two populations, together with their parents and other Upland lines were evaluated in three independent replicated tests for FOV4 responses at 7, 14, 21, and 28 days after inoculation (DAI) under temperature-controlled conditions at 20-21^oC, based on three evaluating parameters- disease incidence (DI), disease severity rating (DSR) and mortality rate (MR). Single nucleotide polymorphic (SNP) markers were used to identify QTL for FW resistance.