Genetics, Breeding, and Marker-Assisted Selection for Verticillium Wilt Resistance in Cotton

Verticillium wilt (VW), caused by the soil-borne fungus Verticillium dahliae Kleb., is one of the most destructive diseases in Upland cotton (Gossypium hirsutum L.) production in the U. S. and worldwide. Development of VW-resistant cultivars remains the only economic option for controlling the disease. The objective of this review was to summarize the progress in screening methods, resistance sources, and genetics, quantitative trait locus (QTL) mapping, marker-assisted selection (MAS) and breeding for VW resistance in cotton. Even though Gossypium barbadense L. carries high levels of resistance, its resistance has not been transferred into commercial Upland cultivars. Many Acala cotton cultivars developed in New Mexico and California between the 1940s and the 1990s, and some commercial transgenic cultivars are tolerant or moderately resistant to VW. However, due to difficulties in achieving consistent and uniform inoculation and infection with V. dahliae, both qualitative and quantitative inheritance of VW resistance have been reported in numerous studies for resistant G. barbadense and Upland genotypes. Several QTL analyses have shown the existence of VW resistance QTLs on almost all the tetraploid cotton chromosomes; however, QTLs have most frequently been detected on c5, c7, c8, c11, c16, c17, c19, c21, c23, c24, and c26. This has led to MAS for progeny with favorable QTL alleles for VW resistance in several experiments. Phenotypic selection for VW resistance has been inefficient, while the effectiveness and efficiency of MAS remain to be validated. There is an urgent need for the development of better plant inoculation and screening methods, and for more molecular mapping studies to discern the genetic basis of VW resistance in cotton.