QTL analysis of resistance to Mal de Río Cuarto disease in maize using recombinant inbred lines

BONAMICO, N.; DI RIENZO, M.; IBAÑEZ, M.; BORGHI, M.; DIAZ, D.; SALERNO, J.; BALZARINI, M.

JOURNAL OF AGRICULTURAL SCIENCE

CAMBRIDGE UNIV PRESS

Año: 2012 p. 1 - 11

0021-8596

Mal de Río Cuarto (MRC) is a devastating disease that reduces yield, quality and 9 economic value of maize in Argentina. Our objective was to map quantitative trait loci 10 (QTL) for reactions to MRC from recombinant inbred lines (RILs). Reactions to the 11 endemic MRC disease were evaluated in 145 advanced F2:6 lines, derived from a cross 12 between a resistant (BLS14) and a susceptible (Mo17) line, at four environments in the 13 temperate semi-arid crop region of Argentina. The evaluations of disease score (SCO), 14 incidence (INC), and severity (SEV) were carried out on each individual RIL. Low 15 heritability estimates across environments for SCO (0·23), INC (0·27) and SEV (0·22) were found. A genetic map of simple sequence repeat (SSR) markers covering a total genetic distance of 1019 cM was built. We detected QTL for resistance to MRC disease on different maize chromosomes. Four significant QTL each explaining between 0·08 19 and 0·14 of the total phenotypic variation were located on chromosomes 1, 4, and 10. Two QTL specific to the INC, and one specific to SEV may be involved in different mechanisms of resistance to MRC. Although MRC reaction is highly affected by environmental effects, the QTL by environment interaction for INC and SEV was low. Most of the QTL for reaction to MRC detected in this study were mapped to regions of the maize genome containing genes conferring resistance to various pathogens. The significant QTL across environments are good candidates to select for MRC resistance.