Molecular mapping of quantitative trait loci for drought tolerance in maize plants

Abstract

ABSTRACT. Drought tolerance is one of the most important but complex traits of crops. We looked for quantitative trait loci (QTLs) that affect drought tolerance in maize. Two maize inbreds and their advanced lines were evaluated for drought-related traits. A genetic linkage map developed using RFLP markers was used to identify QTLs associated with drought-related traits. Twenty-two QTLs were detected, with a minimum of one and a maximum of nine for drought-related traits. A single-QTL was detected for sugar concentration accounting for about 52.2% of the phenotypic variation on chromosome 6. A single-QTL was also identified for each of the traits root density, root dry weight, total biomass, relative water content, and leaf abscisic acid content, on chromosomes 1 and 7, contributing to 24, 0.2, 0.4, 7, and 19% of the phenotypic variance, respectively. Three QTLs were identified for grain yield on chromosomes 1, 5, and 9, explaining 75% of the observed phenotypic variability, whereas four QTLs were detected for osmotic potential on chromosomes 1, 3, and 9, together accounting for 50% of the phenotypic variance. Nine QTLs were detected for leaf surface area on chromosomes 3 and 9, with various degrees of phenotypic variance, ranging from 25.8 to 42.2%. Four major clusters of QTLs were identified on chromosomes 1, 3, 7, and 9. A QTL for yield on chromosome 1 was found co-locating with the QTLs for root traits, total biomass, and osmotic potential in a region of about 15 cM. A cluster of QTLs for leaf surface area were coincident with a QTL for osmotic potential on chromosome 3. The QTLs for leaf area also clustered on chromosome 9, whereas QTLs for leaf abscisic acid content and relative water content coincided on chromosome 7, 10 cM apart. Co-location of QTLs for different traits indicates potential pleiotropism or tight linkage, which may be useful for indirect selection in maize improvement for drought tolerance.

Discovery, Biosynthesis and Stress-Related Accumulation of Dolabradiene-Derived Defenses in Maize

“…In contrast, the induced accumulation of kauralexins was shown previously in stems and scutella tissues to exceed 100 mg g 21 fresh weight as compared with the 10 mg g 21 fresh weight currently detected in mature roots . Notably, ZmAN2 is located proximal to a quantitative trait locus mapped to bin 1.03 that is associated with root growth (Rahman et al, 2011), and ZmKSL4 colocates in bin 1.08 with quantitative trait loci associated with both drought tolerance (Tuberosa et al, 2002) and abscisic acid biosynthesis, which can further mediate drought-induced phytoalexin biosynthesis in maize roots (Vaughan et al, 2015). Our findings here contribute to a growing body of knowledge demonstrating roles for root diterpenoids, including momilactone phytoalexins in rice (Toyomasu et al, 2008), the antiherbivory activity of rhizathalene in Arabidopsis (Arabidopsis thaliana; Vaughan et al, 2013), and drought tolerance mediated by isorosmanol in rosemary (Rosmarinus officinalis; Munné-Bosch and Alegre, 2000).…”

Genome-Wide Association Study Reveals Natural Variations Contributing to Drought Resistance in Crops

“…Thus, many studies have focused on the identification of QTLs that could enhance the concentration of ABA under stress in an attempt to better understand drought tolerance (Lebreton et al, 1995; Sanguineti et al, 1999; Landi et al, 2005; Rahman et al, 2011; Iehisa et al, 2014; Barakat et al, 2015). Specially, Landi et al (2005) found a major maize QTL for L-ABA in bin 2.04 which indicated that the QTL not only enhances yield but also affects root architecture under drought conditions.…”

Genotyping-by-Sequencing in Plants

“…The mapping of underlying quantitative trait loci (QTL) has been made possible by the emergence of molecular markers, genotyping technologies and related statistical methodologies [1]. Initially, the identification of QTL was mostly based on linkage mapping strategies, where polymorphisms between two parents are detected in a segregating population, and the linkage of a particular region to a given phenotype can be determined by genotyping recombinants exhibiting phenotypic variations for a trait of interest [21,113]. However, the relatively small number of recombinants generated from two parents in a limited number of generations means that linkage mapping generally has low resolution, encompassing very large genetic and physical distance, with many possible candidate genes for a trait of interest.…”