Biosafety
 Microbial Biotechnology
Electronic Journal of Biotechnology ISSN: 0717-3458 Vol. 13 No. 5, Issue of September 15, 2010
© 2010 by Pontificia Universidad Católica de Valparaíso -- Chile Received March 9, 2010 / Accepted June 7, 2010
DOI: 10.2225/vol13-issue5-fulltext-1  
REVIEW ARTICLE

The genetic dissection of quantitative traits in crops

Kassa Semagn*
International Maize and Wheat Improvement Center
Nairobi, Kenya
E-mail: K.Semagn@cgiar.org 

Åsmund Bjørnstad
Department of Plant and Environmental Sciences
Norwegian University of Life Sciences
Ås, Norway

 Yunbi Xu
International Maize and Wheat Improvement Center
Mexico D.F., Mexico

Jonathan J. Crouch
International Maize and Wheat Improvement Center
Mexico, D.F., Mexico

*Corresponding author

Financial support: The Bill & Melinda Gates Foundation.

Keywords: association mapping, linkage disequilibrium, markers assisted selection, molecular breeding, molecular markers, quantitative trait, QTL mapping, QTL analysis.

Abbreviations:

ANOVA: analysis of variance
BSA: O-bis (trimethylsilyl) acetamide
FDS: freeze dried supernatant
FPBs: fermented plant beverages
GC-MS: gaschromatography- mass spectrometry
GR: growth rate
HPLC: High performance liquid chromatography
LAB:  lactic acid bacteria
LWR: liver weight ratio
PBS: phosphate buffer saline
PLA: phenyllactic acid
QTL: quantitative trait loci
SWI: spleen weight index
TMS: Trimethylsilyl

Abstract   Full Text

Most traits of interest in plant breeding show quantitative inheritance, which complicate the breeding process since phenotypic performances only partially reflects the genetic values of individuals. The genetic variation of a quantitative trait is assumed to be controlled by the collective effects of quantitative trait loci (QTLs), epistasis (interaction between QTLs), the environment, and interaction between QTL and environment. Exploiting molecular markers in breeding involve finding a subset of markers associated with one or more QTLs that regulate the expression of complex traits. Many QTL mapping studies conducted in the last two decades identified QTLs that generally explained a significant proportion of the phenotypic variance, and therefore, gave rise to an optimistic assessment of the prospects of markers assisted selection. Linkage analysis and association mapping are the two most commonly used methods for QTL mapping. This review provides an overview of the two QTL mapping methods, including mapping population type and size, phenotypic evaluation of the population, molecular profiling of either the entire or a subset of the population, marker-trait association analysis using different statistical methods and software as well as the future prospects of using markers in crop improvement.

Supported by UNESCO / MIRCEN network