Plant Genome IV Conference Plant Genome IV Conference
Molecular markers were used to investigate quantitative trait loci (QTL) for height growth in an selfed progeny of maritime pine. F2 seedlings were raised during two years in a greenhouse under accelerated growth conditions consisting in intense fertilization combined with continuous light treatments of several weeks. Total height was measured at three developmental stages. One to three QTLs were identified in different linkage groups of the genetic map for each stage. This differential QTL expression during the development suggested that different loci are likely to be involved in the genetic control of height growth at different ages. However, two kinds of QTLs could be observed: genomic regions showing a progressive expression during the plant growth and genomic regions strongly expressed only at one of the three stages of the development. Thus, rather than a complete temporal change in QTL expression, it seems that maturation also induces a progressive shift of the genetic control of height growth. If the same metabolic pathways are assumed to be responsible for height growth in both juvenile and more mature developmental stages, our results indicate that different regulatory genes or differential expressions of the same set of regulatory genes could be involved in the genetic control of height growth at different stages of maturation.