Plant Genome IV Conference Plant Genome IV Conference
Genetic maps constructed using molecular markers allow loci controlling quantitative trait (QTLs) to be detected, and their effects to be estimated. We are using this approach for characterizing QTLs of traits responsive to water deprivation in maize. In addition to anonymous probes, we map probes corresponding to genes induced by mild water stress. The expectation is that the polymorphism of some of these genes result in quantitative variation of drought response traits. Two methods are used to choose these genes: (i) direct selection of cDNAs by subtractive hybridization of cDNA libraries; (ii) search for proteins induced or up-regulated by drought deprivation. The traits measured in the field (agronomic traits) and in the greenhouse (photosynthesis, water status and carbon metabolism traits, ABA content) displayed large genotypic variability in the RIL population analyzed, with frequent transgressive genotypes. Agronomic and physiological QTLs have been mapped. Moreover mapping QTLs involved in the level of induction of the responsive proteins is in progress, to search for cosegregations with agronomic or physiological QTLs. Sequences of some of the induced proteins revealed functions relevant to drought response.