Quantitative Disease Resistance: Dissection and Adoption in Maize

Abstract

Maize is the world's most produced crop, providing food, feed, and biofuel. Maize production is constantly threatened by the presence of devastating pathogens worldwide. Characterization of the genetic components underlying disease resistance is a major research area in maize which is highly relevant for resistance breeding programs. Quantitative disease resistance (QDR) is the type of resistance most widely used by maize breeders. The past decade has witnessed significant progress in fine-mapping and cloning of genes controlling QDR. The molecular mechanisms underlying QDR remain poorly understood and exploited. In this review we discuss recent advances in maize QDR research and strategy for resistance breeding.

Meta‐Analysis of QTL Studies for Resistance to Fungi and Viruses in Maize

“…Quantitative resistance usually causes reduction in disease severity but not the absence of disease in plants and can be a source of durable resistance or tolerance (French et al, 2016). However, a better understanding of the genetic mechanisms underlying resistance is still necessary (Ali et al, 2013;Yang et al, 2017). In maize, obtaining quantitative resistance to major diseases is a central focus in breeding programs.…”

“…The loci involved in quantitative resistance can be sorted by the magnitude of their effects and classified as major-or minor-effect loci in determining resistance to diseases of interest. In addition, the most economically important maize diseases are caused by necrotrophic pathogens, and resistance to such diseases is almost exclusively quantitative rather than qualitative (Balint-Kurti and Johal, 2009;Yang et al, 2017). However, a better understanding of the genetic mechanisms underlying resistance is still necessary (Ali et al, 2013;Yang et al, 2017).…”

“…However, a better understanding of the genetic mechanisms underlying resistance is still necessary (Ali et al, 2013;Yang et al, 2017). Yang et al (2017) reported 12 cloned disease resistance genes in maize. This is probably because maize is a naturally outcrossing species, and the genetic architecture controlling quantitative traits is more complex than in self-pollinating plants.…”

“…In the last decade, important progress has been made in fine F2 193/144/337 Zwonitzer et al (2010) GLS/SLB/NLB Ki14 × B73 RIL 109 † SDM, sorghum downy mildew; SLB, southern leaf blight; GLS, gray leaf spot; NLB, northern leaf blight; CS, common smut; AFL, aflatoxin; PLS, Phaeosphaeria leaf spot; FER, Fusarium ear rot; DM, downy mildew; GER, Giberella ear rot; SCR, southern corn rust; CLS, Curvularia leaf spot; ASR, anthracnose stalk rot; HS, head smut; CR, common rust; RDM, Rajasthan downy mildew; AER, Aspergillus ear rot; MSR, maize stalk rot; ER, ear rot; MSB, maize sheath blight; GSR, Gibberella stalk rot. mapping and cloning of genes controlling quantitative resistance to diseases, and 12 genes and QTL have been cloned (Yang et al, 2017). § RIL, recombinant inbred lines; F2, F 2:3 families; DH, double haploids; IL, inbred lines; TCF2, testcrosses of F 2:3 families; BCP1S1, families selfed once from backcrosses to parent one; F4, F 4 families, F5, F 5 families; BC1F2, F 2 families derived from backcross; BC1F1, F 1 families derived from backcross; BC1S1, families selfed once from backcross.…”

“…‡ DP, diverse population; CP, combined population. For fungal disease in bin 1.06 of chromosome 1, Yang et al (2017) Forest plot from the meta-analysis for chromosome 10 of the maize genome, showing odds ratio (OR) and 95% confidence intervals (95%-CI) of OR per each primary study, and the global OR obtained as a weighted mean by a random effect model accounting for heterogeneity among primary studies. mapping and cloning of genes controlling quantitative resistance to diseases, and 12 genes and QTL have been cloned (Yang et al, 2017).…”