ARS | Publication request: DEFENSE RESPONSES OF COTTON TO VERTICILLIUM WILT

Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Abstract Only
Publication Acceptance Date: January 9, 2000
Publication Date: N/A

Technical Abstract: Four cultivars (Pima S-7, M-315, Acala 44, and Acala Prema) were tested for disease severity and response to four Verticillium dahliae isolates (PH, TS-2, V76, and V44). Pima S-7 followed by Acala Prema was the most resistant and Acala 44 the most susceptible to the pathogen. Pima S-7 (G. barbadense) was chosen as the resistant parent and Acala 44 (G. hirsutum) the susceptible one and crosses were made in the field. F1 and F2 generations were grown in the greenhouse along with the parents and inoculated using the V76 isolate. F2 frequency distributions for number of diseased leaves per plant, number of attached leaves, total plant weight, and leaf to stem ratio showed segregation for resistance to V. dahliae, and a near normal distribution for the parameters measured, as expected for a quantitative train. Also, the F2 distribution indicated transgressive segregation for resistance. DNA was extracted from the parents and 110 F2 plants. Ten resistant and 10 susceptible F2 plants from the extreme phenotypes were bulked (Bulk Segregate Analysis-BSA) Random Amplified Polymorphic DNAs (RAPDs) were used for the BSA and individual F2 plants will be genotyped with the primers that are polymorphic in the BSA. Polymorphic bands were detected between the Pima S-7 and Acala 44 parents and the F2 resistant and susceptible bulks. Twenty-four RAPD primers were screened and three were polymorphic. Work is in progress to screen additional markers for resistance to V. dahliae.