Semidwarfism has been used extensively in row crops and horticulture to promote yield, reduce lodging, and improve harvest index, and it might have similar benefits for trees for short-rotation forestry or energy plantations, reclamation, phytoremediation, or other applications. The causative genes are being identified with a genetical genomics approach. Pleiotropic loci linking higher growth rates to wood with less lignin are excellent targets to engineer tree germplasm improved for pulp, paper and cellulosic ethanol production. A highly significant genetic correlation was observed between plant growth and lignin/cellulose composition, and quantitative trait loci co-localization identified the genomic position of potential pleiotropic regulators. The majority of quantitative trait loci are specific to one of the two nitrogen treatments, demonstrating significant nitrogen-dependent genetic control. Sixty-three more » quantitative trait loci were identified for the 20 traits analyzed. The loci that regulate growth, carbon allocation and partitioning under two nitrogen conditions were identified, defining the contribution of environmental cues to their genetic control. We phenotyped 396 clonally replicated genotypes of an interspecific pseudo-backcross pedigree of Populus for wood composition and biomass traits in above- and below-ground organs. It is also unclear how environmental cues, such as nitrogen availability, impact the genes that regulate growth, biomass allocation and wood composition in trees. The genetic control of carbon allocation and partitioning in woody perennial plants is poorly understood despite its importance for carbon sequestration, biofuels and other wood-based industries. The work developed more » in this project resulted in the publication of three book chapters, four scientific articles (three others currently in preparation), 17 presentations in international conferences and two provisional patent applications. By integrating the QTL and gene expression information we identified genes that regulate carbon partitioning and several biomass growth related properties. Gene expression analysis of all poplar genes was also characterized in differentiating xylem, whole-roots and developing leaves of 192 of the segregating population. A highly significant genetic correlation was observed between plant growth and lignin/cellulose composition, and QTL co-localization identified the genomic position of potential pleiotropic regulators. The majority of QTL are specific to one of the two nitrogen treatments, demonstrating significant nitrogen-dependent genetic control. Fifty-seven quantitative trait loci (QTL) were identified for twenty traits analyzed.
To address these questions we phenotyped 396 clonally replicated genotypes of an interspecific pseudo-backcross pedigree of Populus for wood composition and biomass traits in above and below ground organs.
It is also unclear how environmental cues such as nitrogen availability impact the genes that regulate growth, and biomass allocation and wood composition in trees. The genetic control of carbon allocation and partitioning in woody perennial plants is poorly understood despite its importance for carbon sequestration.