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Title: Analysis of quantitative disease resistance to southern leaf blight and of multiple disease resistance in maize, using near-isogenic lines

Author
item BLECHER, ARABY - North Carolina State University
item ZWONITZER, JOHN - North Carolina State University
item SANTA CRUZ, JOSE - North Carolina State University
item Krakowsky, Matthew
item CHUNG, CHIA-LIN - Cornell University
item NELSON, REBECCA - Cornell University
item ARELLANO, CONSUELO - North Carolina State University
item Balint-Kurti, Peter

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/3/2011
Publication Date: 10/14/2011
Citation: Blecher, A., Zwonitzer, J., Santa Cruz, J., Krakowsky, M.D., Chung, C., Nelson, R., Arellano, C., Balint Kurti, P.J. 2011. Analysis of quantitative disease resistance to southern leaf blight and of multiple disease resistance in maize, using near-isogenic lines. Theoretical and Applied Genetics. 124:433-445.

Interpretive Summary: In this paper we compare two closely-related lines, one of which is very susceptible to the disease southern leaf blight and one is which is very resistant. Previously we had shown that these two lines share ~95% of their genomes but that they differed in 12 relatively small regions (introgressions). In this paper we developed a set of lines in which differed for only one or two of these introgressions. Using these lines we showed that only 3 of the 12 introgressions were important for southern leaf blight resistance. We also showed that at least two of these regions also conferred resistance to a second disease.

Technical Abstract: Maize inbred lines NC292 and NC330 were derived by repeated backcrossing of an elite source of southern leaf blight (SLB) resistance (NC250P) to the SLB-susceptible line B73, with selection for SLB resistance among and within backcross families at each generation. Consequently, while B73 is very SLB susceptible, the nearly-isogenic lines (NILs) NC292 and NC330 are both SLB resistant. Previously we identified the 12 introgressions from NC250P that differentiate NC292 and NC330 from B73. The goals of this study were to determine the effects of each introgression on resistance to SLB and to two other foliar fungal diseases of maize, northern leaf blight (NLB) and grey leaf spot (GLS). This was achieved by generating and testing a set of NILs carry single or combinations of just two or three introgressions in a B73 background. Introgressions 3B, 6A, and 9B (bins 3.03-3.04, 6.01, and 9.02-9.03) all conferred significant levels of SLB resistance in the field. Introgression 6A was the only introgression that had a significant effect on juvenile plant resistance to SLB. Introgressions 6A and 9B both conferred significant levels of resistance to an additional disease (NLB and GLS respectively).