Joint linkage–linkage disequilibrium mapping is a powerful approach to detecting quantitative trait loci underlying drought tolerance in maize

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 107; no. 45; pp. 19585 - 19590
• Main Authors: Lu, Yanli, Zhang, Shihuang, Shah, Trushar, Xie, Chuanxiao, Hao, Zhuanfang, Li, Xinhai, Farkhari, Mohammad, Ribaut, Jean-Marcel, Cao, Moju, Rong, Tingzhao, Xu, Yunbi, Zhang, Qifa
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 09-11-2010; National Acad Sciences
• Subjects: Acclimatization - genetics; Alcohol Oxidoreductases - genetics; Aldehyde Reductase; Aldo-Keto Reductases; Alleles; Biological Sciences; Cells; Chromosomes; Computational Biology; Corn; Detoxification; Drought resistance; Droughts; Environmental stress; Flowering; Flowers - genetics; Gene frequency; Gene loci; Genetic diversity; Genetic linkage; Genetic loci; Genomics; Genotype & phenotype; Haplotypes; Inbreeding; Joints; Linkage analysis; Linkage Disequilibrium; Phenotype; Phenotypic traits; Plants; Polymorphism; Polymorphism, Single Nucleotide; Population genetics; Population structure; Quantitative Trait Loci; reductase; Single-nucleotide polymorphism; Zea mays; Zea mays - genetics; Zea mays - physiology
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1006105107

This paper describes two joint linkage–linkage disequilibrium (LD) mapping approaches: parallel mapping (independent linkage and LD analysis) and integrated mapping (datasets analyzed in combination). These approaches were achieved using 2,052 single nucleotide polymorphism (SNP) markers, including 659 SNPs developed from drought-response candidate genes, screened across three recombinant inbred line (RIL) populations and 305 diverse inbred lines, with anthesis-silking interval (ASI), an important trait for maize drought tolerance, as the target trait. Mapping efficiency was improved significantly due to increased population size and allele diversity and balanced allele frequencies. Integrated mapping identified 18 additional quantitative trait loci (QTL) not detected by parallel mapping. The use of haplotypes improved mapping efficiency, with the sum of phenotypic variation explained (PVE) increasing from 5.4% to 23.3% for single SNP-based analysis. Integrated mapping with haplotype further improved the mapping efficiency, and the most significant QTL had a PVE of up to 34.7%. Normal allele frequencies for 113 of 277 (40.8%) SNPs with minor allele frequency (<5%) in 305 lines were recovered in three RIL populations, three of which were significantly associated with ASI. The candidate genes identified by two significant haplotype loci included one for a SET domain protein involved in the control of flowering time and the other encoding aldo/keto reductase associated with detoxification pathways that contribute to cellular damage due to environmental stress. Joint linkage–LD mapping is a powerful approach for detecting QTL underlying complex traits, including drought tolerance.