Quantitative genetic analysis of biomass and wood chemistry of Populus under different nitrogen levels

Abstract

Summary 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. It is also unclear how environmental cues, such as nitrogen availability, impact the genes that regulate growth, biomass allocation and wood composition in trees. 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. 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. Sixty‐three quantitative trait loci were identified for the 20 traits analyzed. The majority of quantitative trait loci are specific to one of the two nitrogen treatments, demonstrating significant nitrogen‐dependent genetic control. 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. 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. The causative genes are being identified with a genetical genomics approach.

Lignin and Biomass: A Negative Correlation for Wood Formation and Lignin Content in Trees

“…Similar to the results previously observed in Eucalyptus (Kirst et al, 2004), expression of lignin biosynthesis genes was coordinated with aboveground growth in the segregating family of Populus analyzed by Novaes et al (2009). Analysis of this population with whole-transcriptome microarrays developed to discriminate among members of gene families ( Fig.…”

“…Correlations (Spearman) of biomass growth (biom) and lignin levels with transcript abundance of specific monolignol biosynthetic genes in a interspecific pseudo-backcross pedigree of Populus (family 52-124). Analysis of lignin and microarrays estimates of relative abundance are from Novaes et al (2009) and Drost et al (2010). Each step of the pathway is shown with the specific genes known to be highly expressed in differentiating xylem in P. trichocarpa (Shi et al, 2010).…”

“…Studies in populations of forest tree hybrids have shown a negative correlation of biomass growth (usually measured as wood volume) and lignin content (Kirst et al, 2004;Novaes et al, 2009). The control of growth and lignin appears to be highly regulated, implying that selection for improved growth rate could effect a reduction in lignin content.…”

Comparison of Pyrolysis Mass Spectrometry and Near Infrared Spectroscopy for Genetic Analysis of Lignocellulose Chemical Composition in Populus

“…Data cleaning was conducted by removing outliers and recording errors as reported by Novaes et al [10]. The mixed model used in this paper was the same as before [10]:…”

“…The experimental design, sample processing and collection of pyMBMS data are described in detail by Novaes et al [10]. Briefly, ground samples of wood were available from 2376 plants from 396 genotypes grown under two different nitrogen treatments (with ~3 clonal replicates) and then harvested after 10 weeks.…”