ARS | Publication request: ANALYSIS OF QUANTITATIVE TRAIT LOCI FOR RESISTANCE TO SOUTHERN LEAF BLIGHT IN JUVENILE MAIZE.

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 20, 2005
Publication Date: March 1, 2006
Citation: Balint Kurti, P.J., Carson, M.L. 2006. Analysis of quantitative trait loci for resistance to southern leaf blight in juvenile maize.. Phytopathology.

Interpretive Summary: Southern leaf blight (SLB) is an important disease of corn. In order to study it in detail we need to use young plants grown under controlled conditions in the greenhouse. This study was undertaken to determine whether SLB resistance has the same basis on young greenhouse-grown plants as in older plants grown in the field. While overall resistance displayed was quite different between the two growth stages, certain genes (or loci) seemed to be working in a similar fashion at both stages.

Technical Abstract: A set of 192 maize recombinant inbred lines (RI lines), derived from a cross between the inbred lines Mo17 and B73, were evaluated as 3 week'old seedlings in the greenhouse for resistance to southern leaf blight (SLB), caused by C. heterostrophus race O. Six significant (L.O.D >3) quantitative trait loci (QTL) were identified for disease resistance on chromosomes 1, 2, 3, 6, 7 and 8. Results were compared with a previous study, which had used the same RI line population and pathogen isolate, but had examined resistance in mature rather than juvenile plants. Although there was no significant correlation between the overall resistance phenotypes of the RI lines scored as mature and juvenile plants, two QTL were found in similar positions on chromosomes 1 and 3 at both growth stages. Other QTL were specific to one growth stage or the other. A subset of these RI lines were inoculated in the greenhouse with four C. heterostrophus isolates. Results indicated that the majority of the quantitative resistance observed was isolate non-specific.