Expression of three phenylpropanoid pathway genes in Scots pine (Pinus sylvestris L.) in open-pollinated families with differing relative wood densities during early and late wood formation

Abstract

Wood volume and quality are the most important aspects of commercial forestry production, and studies of wood formation are important in order to increase the value and efficiency of forestry production. The phenylpropanoid pathway produces various compounds with diverse functions both for plant defence against biotic and abiotic stress as well as structural development. One of the main roles is monolignol production for lignin biosynthesis, which is a crucial aspect of wood formation. For this study three candidate genes involved in lignin biosynthesis were selected: phenylalanine ammonialyase (PAL1), cinnamyl alcohol dehydrogenase (CAD) and cinnamoyl-CoA reductase (CCR). Candidate gene expression was analysed in selected individuals with high and low wood density from open-pollinated Scots pine families during early wood (EW) and late wood (LW) formation and correlation between expression of these genes, total lignin content, and wood density was determined. Wood density values for analysed trees were similar within tree families but differed significantly between families with high and low wood density (p = 1,06E-20). Wood density was slightly negatively correlated with lignin content (r = -0.36, p = 0.038), but only in individuals in the high density wood group. In trees with low wood density, expression of the CAD gene was significantly lower in late wood formation compared to early wood (p = 0.00179). In trees with high wood density, expression of the PAL1 gene was five times higher during early wood formation compared to late wood formation. A positive correlation was detected between PAL1 and CCR gene expression during early wood formation (r = 0.804) and late wood formation (r = 0.466).

Bayesian Mapping Reveals Large-Effect Pleiotropic QTLs for Wood Density and Slenderness Index in 17-Year-Old Trees of Eucalyptus cladocalyx

“…Wood density and other mechanical properties are highly variable among species and sites, and even between and within the trees themselves [20]. Due to the relevance of this type of trait for the wood industry, several studies have been developed to estimate genetic parameters and identify genes, or regions in the genome, related to the production of structural components of wood (for example, cellulose and lignin) and the spatial arrangement of the microfibrils [21][22][23][24][25][26]. In general, these studies have been explored with molecular markers and transcriptomic analyzes in the principal forest species.…”

Expression of the Scots pine (Pinus sylvestris) TIP-like and sucrose synthase genes during two growing seasons and correlation with relative wood densities

“…In addition, the results presented in this report are average expression levels over a number of individuals, while the previous reports were mostly based on analysis of a single individual. Expression levels of three lignin biosynthesis genes were previously investigated in the same plant material (Kanberga-Silina et al 2015), and large differences in expression levels were detected between individuals. This variation of gene expression between individuals also needs to be considered when comparing gene expression levels.…”