Résumé
Phenotypic changes in plants can be observed along many environmental
gradients and are determined by both environmental and genetic factors.
The identification of alleles associated with phenotypic variations is a
rapidly developing area of research. We studied the genetic basis of
phenotypic variations in 11 populations of wild pearl millet (Pennisetum
glaucum) on two North-South aridity gradients, one in Niger and one in
Mali. Most of the 11 phenotypic traits assessed in a common garden
experiment varied between the populations studied. Moreover, the size of
the inflorescence, the number of flowers and aboveground dry mass
co-varied positively with a decrease in rainfall. To decipher the genetic
basis of these phenotypes, we used an association mapping strategy with a
mixed model. We found two SNPs on the same myosin XI contig significantly
associated with variations in the average number of flowers. Both the
allele frequency of the two SNPs and the average number of flowers
co-varied with the rainfall gradient on the two gradients. Interestingly,
this gene was also a target of selection during domestication. The Myosin
XI gene is thus a good candidate for fitness-related adaptation in wild
populations.