Genetic mapping and characterization of Verticillium Wilt resistance in a recombinant inbred population of Upland cotton

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Abstract: Verticillium wilt (VW) is an important and widespread disease of cotton and once established is long lived and difficult to manage. In Australia, the non-defoliating pathotype of Verticillium dahliae is the most common and extremely virulent. Breeding cotton varieties with increased VW resistance is the most economical and effective method of controlling this disease, and is greatly aided by understanding the genetics of resistance. In this study VW resistance was investigated in 240 F7 recombinant inbred lines (RIL) derived from a cross between MCU-5 that has good resistance and Siokra 1-4 which is susceptible. Using a controlled environment bioassay, resistance based on plant survival or shoot biomass was complex but with major contributions from chromosomes D03 and D09. with genomic prediction analysis estimating a prediction value of 0.73 based on survival scores compared to 0.36 for shoot biomass. Transcriptome analysis of MCU-5 and Siokra 1-4 roots infected with VW revealed that the two cultivars displayed very different root transcriptomes. Cross checking between differentially expressed genes that are located to the mapped resistance regions, identified 104 potential candidates associated with VW resistance.