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Title: REACTION OF COTTON CULTIVARS AND AN F2 POPULATION TO STEM INOCULATION WITH ISOLATES VERTICILLIUM DAHLIAE

Author
item BOLEK, Y - TEXAS A&M UNIV
item Bell, Alois - Al
item EL-ZIK, K - TEXAS A&M UNIV
item THAXTON, P - TEXAS A&M UNIV
item MAGILL, C - TEXAS A&M UNIV

Submitted to: Journal of Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/8/2005
Publication Date: 6/8/2005
Citation: Bolek, Y., Bell, A.A., El-Zik, K.M., Thaxton, P.M., Magill, C.W. 2005. Reaction of cotton cultivars and an F2 population to stem inoculation with isolates of Verticillium dahliae. Journal of Phytopathology. 153:1-5.

Interpretive Summary: Studies were conducted to identify the best cotton cultivars and Verticillium strains for use in genetic mapping of resistance genes. Various measurements of resistance also were compared to identify those most useful. The studies identified Acala 44 and Pima S-7 as the best susceptible and resistant cultivars. Verticillium dahliae strain, V76, was most useful for distinguishing levels of resistance. The number of healthy leaves and total shoot weight were the best quantitative measures of resistance. These parameters have been used in a mapping study.

Technical Abstract: Four Verticillium dahliae isolates were used in screening four cotton cultivars. Pima S-7 and Acala Prema gave the highest resistance reactions and Acala 44 was the most susceptible. Isolate V76 of V. dahliae was the most virulent. An interspecific cross between the resistant cv. Pima S-7 and the susceptible cv. Acala 44 was made and the F2 population phenotyped for Verticillium wilt effect. Phenotyping of plant reaction to the disease was quantified by using a set of six growth parameters measured 3 weeks after inoculation. The F2 phenotypic distribution of these parameters suggests that distribution is towards resistance and polygenic. Transgressive segregation also was observed. The number of healthy leaves and total shoot weight were found to be the best indicators of resistance. Results obtained in this study will be useful to quanitify resistance to V. dahliae and identify the best parameters to phenotpye in genetic studies.