Résumé
Aroma in cultivated rice is more and more appreciated in Europe. Unfortunately, aromatic cultivars often show undesirable agronomie characters. Thus, breeders wish to develop high-yielding aromatic varieties adapted to European constraints. Many contradictory studies have been reported concerning the genetic control of aroma in rice. Thus, it was of interest to approach the problem using recently developed tools. The approach presented here involved a combination of two techniques. The first was quantification of volatile compounds in the cooking water of grains by gas chromatography. This technique allowed the analysis of grain aroma as a quantitative trait. The second technique was the construction of a genetic map using several types of molecular markers. Evaluations of arome and mapping were performed using a population of doubled haploid (DH) lines derived from the F1 hybrid IR 64 x Azucena. Cosegregation between molecular markers and aromatic character was studied using a QTL detection approach. Segregation analysis allowed us to locate unambiguously on chromosome 8 the gene responsible for the presence of 2-acetyl-1-pyrro line (AcPy), the main compound associated with rice aroma. Estimations of recombination fractions on chromosome 8 were corrected for strong-segregation distortion. Moreover, our results showed that AcPy concentration in plants may be regulated by at least 2 regions on chromosomes 4 and 12. We believe that our results could help understand why a gradient is observed in strength of aroma among scented cultivars. We discuss the implications of these results for rice selection. An immediate application of the tagging of aromatic gene(s) is their marker-assisted introgression into high yielding varieties. (Résumé d'auteur)