Mapeamento e validação de loci de caracteres quantitativos (QTL) para resistência a Cercospora zeae-maydis em milho tropical (Zea mays L.)

by Pozar, Gilberto

Abstract (Summary)
Resistance to infection by Cercospora zeae-maydis (Cz) ranks among the mostimportant objectives of breeding programs in Brazil. The objectives of this researchwere to map and characterize Quantitative Trait Loci (QTL) related to resistance toCz, to validate the estimates of their effects on disease severity using Near-Isogenic Lines (NILs), and to estimate their effects on three major agronomic traitsusing their respective Near Isogenic Hybrids (NIHs) obtained by crossing the NILswith an inbred of complementary heterotic pool. Four QTL with LOD values gt; 2.5were mapped using the Multiple Interval Mapping approach. Three of them wereevaluated in this study. NILs genotype included the two QTL allele located inchromosome 1 in repulsion phase, Q1 in bin 1.05 and Q2 in bin 1.07, and one inchromosome 3, Q3 in bin 3.07. NIL evaluation showed that individually, the threeQTL significantly reduced the severity of Cz. An unfavorable epistatic interactionfor the reaction to Cz was detected between Q1 and Q2, in which one QTL alleleeffectively nullified the effect of the other. Alternatively, the interaction between Q2and Q3 was positive, promoting the reduction of the severity to a greater extentthan the sum of their individual effects. NIH evaluation revealed significantindividual effects for Q1 and Q3 on Cz severity, for Q2 on stalk lodging and grainyield, and for Q3 on grain moisture and stalk lodging. Significant epistaticinteractions were also detected between Q1 and Q2 for grain moisture andbetween Q1 and Q3 for stalk lodging. The combination of QTL impacts theeffectiveness of marker-assisted selection procedures in commercial productdevelopment programs.
This document abstract is also available in Portuguese.
Bibliographical Information:

Advisor:Luiz Ricardo Goulart Filho; Julio Cesar Viglioni Penna; Heyder Diniz Silva; Renzo Garcia Von Pinho; Jose Roberto Moro

School:Universidade Federal de Uberlândia

School Location:Brazil

Source Type:Master's Thesis

Keywords:LinhagensQuase isogênicas (LQI) Epistasia Quantitative Trait Loci (QTL) Near Isogenic Line (NIL) Hybrid (NIH) QTL mapping validation Epistasis


Date of Publication:10/04/2007

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