Mapping QTLs in breeding for drought tolerance in maize (Zea mays L.)

Abstract

Grain yield in the maize (Zea mays L) plant is sensitive to drought in the period three weeks either side of flowering . Maize is well-adapted to the use of restriction fragment length polymorphisms (RFLPs) to identify a tight linkage between gene(s) controlling the quantitative trait and a molecular marker . We have determined the chromosomal locations of quantitative trait loci (QTLs) affecting grain yield under drought, anthesis-silking interval, and number of ears per plant . The F3 families derived from the cross SD34(tolerant) x SD35(intolerant) were evaluated for these traits in a two replicated experiment . RFLP analysis of the maize genome included non-radioactive DNA-DNA hybridization detection using chemiluminescence . To identify QTLs underlying tolerance to drought, the mean phenotypic performances of F3 families were compared based on genotypic classification at each of 70 RFLP marker loci . The genetic linkage map assembled from these markers was in good agreement with previously published maps . The phenotypic correlations between yield and other traits were highly significant . In the combined analyses, genomic regions significantly affecting tolerance to drought were found on chromosomes 1,3,5,6, and 8 . For yield, a total of 50% of the phenotypic variance could be explained by five putative QTLs . Different types of gene action were found for the putative QTLs for the three traits .

Identification of QTLs for Yield and Drought-Related Traits in Maize: Assessment of Their Causal Relationships

“…The same QTLs for yield were identified on 2.09 bin by Beavis (3) and on chromosome 5 by Agrama et al (1). qtl for yield on chromosome 7 in our study was detected in the region between 7.2 -7.03 bins, while several authors detected qtl for yield between 7.04 -7.05 bins (2,3,13,20).…”

Quantitative Trait Loci Mapping of Maize Yield and Its Components Under Different Water Treatments at Flowering Time

“…The mapping and tagging of QTL form the basis of MAS. The identification of QTL for maize drought tolerance has been investigated in many studies and some progress has been made (Agrama et al 1996;Ribaut et al 1996Ribaut et al , 1997Frova et al 1999;Sanguineti et al 1999;Sari-Gorla et al 1999;Gao et al 2003;Li et al 2003Li et al , 2004Zhang et al 2004). However, most of these previous studies have been based on the additive-dominant genetic model on the assumption that there is no interactive effect among the alleles.…”

“…The mapping and tagging of QTL for maize drought tolerance has been reported in many studies (Agrama et al 1996;Ribaut et al 1996Ribaut et al , 1997Sanguineti et al 1999;Sari-Gorla et al 1999;Gao et al 2003;Li et al 2003Li et al , 2004Zhang et al 2004). Agrama and Moussa (1996) reported that there were five QTLs related to grain yield on chromosomes 1, 3, 5, and 8 under drought conditions that could explain 49.6% of the phenotypic variance. Ribaut et al (1997) studied the QTL of grain yield, ear number, kernel number, and 100-kernel weight under well-watered conditions and two other water-stress regimens and identified one to seven QTL for each trait in the different environments.…”

Genomic Dissection of Genotype × Environment Interactions Conferring Adaptation of Cotton to Arid Conditions

“…Using genetic mapping to dissect the inheritance of different complex traits in the same segregating population can be a powerful means to distinguish common heredity from casual associations between such traits (Paterson et al 1988). Genetic mapping has been used to identify quantitative trait loci (QTLs) responsible for improved productivity under arid conditions (Agrama and Moussa 1996;Tuinstra et al 1996;Ribaut et al 1997). Separately, QTLs have also been reported that confer physiological variations thought to be associated with stress tolerance, such as osmotic adjustment (defined as the active accumulation of solutes in response to water deficit as opposed to passive solute concentration caused by water loss; Morgan 1992;Lilley et al 1996;Morgan and Tan 1996), WUE (measured either directly or indirectly as a carbon isotope ratio, 13 C/ 12 C, expressed with a differential notation as ␦ stomatal conductance (Ulloa et al 2000), and various measures of plant water status (Lebreton et al 1995;Teulat et al 1998a).…”