The Genetic Basis of Disease Resistance in Maize - Translational Genomics for Crop Breeding: Biotic Stress - page 31

Chapter 3

The GeneticBasis of Disease
Resistance in Maize

TiffanyJamann,RebeccaNelson,and PeterBalint-Kurti

Abstract

This chapter presents an overview of diseases important to global maize production, outlines the
current understanding of the genetic underpinnings for resistance to these diseases, and explores
how these findings can be used to improve maize. With a primary focus on fungal diseases, we
review the current understanding of qualitative and quantitative resistance. In order to dissect the
genetics of quantitative resistance to three important diseases, new datasets and resources have been
utilized. A number of populations have been evaluated for various maize diseases, including bi-
parental populations, association mapping panels, and the nested association mapping population.
By generating lists of genes suspected to be involved in the interaction between plant and pathogen,
both genome-wide association mapping and nested association mapping have provided hints about the
biology of disease resistance. As part of the study of the architecture of disease resistance, both single-
disease resistance and multiple-disease resistance have been explored. Multiple-disease resistance is
rare, but some genes apparently confer resistance to multiple pathogens. As high-resolution mapping
becomes available, the challenge remains to translate this knowledge into breeding outcomes. Marker-
assisted selection can be used to utilize these results, but there is a disconnect between the wealth of
mapping information and the application of this data. Genomic selection is emerging as a powerful
tool for maize improvement. The challenge, however, remains to apply mapping studies and basic
biology to plant breeding to decrease the amount of maize lost to pathogens.

diseases worldwide, excluding viruses, have
been estimated at 4-14% of global annual
harvest (Oerke 2006). It is thus increasingly
important to reduce losses due to diseases.
Several pathogens cause grain yield losses,
whereas others contaminate maize seeds with
mycotoxins, a widespread hazard to human and
animal health (Wild and Gong 2010).

Introduction

Biotic stresses constrain maize production
worldwide, affecting food security and prices.
Population growth and the use of grain for
biofuels spurs demand, while climate variability,
as well as rising costs of fertilizer and water,
challenge supply. Crop losses caused by maize