Variation in Birch (Betula pendula) Shoot Secondary Chemistry due to Genotype, Environment, and Ontogeny

Abstract

Plant secondary chemistry is determined by both genetic and environmental factors, and large intraspecific variation in secondary chemistry has frequently been reported. The heritability of specific tree secondary metabolites is, however, mostly unknown. We tested the effect of plant genotype, environment, and ontogeny on the variation in shoot secondary chemistry of juvenile and mature European white birches (Betula pendula). Phenolic compounds and triterpenoids were analyzed in 30 naturally regenerated 20-year-old parental trees and micropropagated plantlets that originated from 14 of those same parental trees, planted at four growing sites. Most of the variation for phenolic compounds was explained by differences between parental trees, whereas triterpenoids had a high variation both between parental trees and within the canopy of individual tree. The effect of ontogeny was strong for some individual compounds. In mature trees, the amount of triterpenoids was less than 1 mg/g (DW), whereas the concentration in juvenile plantlets was up to 64 mg/g (DW). Clonal plantlets and parental trees were generally quite similar in their phenolic contents, but there were significant differences for all analyzed compounds among clones. Environment had no significant effect on the accumulation of some compounds, whereas for others, a significant environmental effect and/or significant genotype by environment interaction was found. These results suggest that birch shoot secondary chemistry is under strong genetic control and that the environmental effects depend on the studied chemical trait.

Phenolic metabolites in the resistance of northern forest trees to pathogens — past experiences and future prospects

“…The authors suggested that phenolic compounds that were likely to contribute to Melampsora medusae rust immunity were present in immature leaves. In birch, however, the main phenolic compounds were found to be the same in both mature trees and clonal plantlets of the same trees (Laitinen et al 2005), and most of the variation was explained by differences among parental trees, indicating genetic control of phenolic compounds.…”

“…Marked intraspecific variations in disease resistance (Elamo et al 2000;Nagy et al 2004), as well as in phenolic content (Hakulinen et al 1999;Laitinen et al 2005;Haviola et al 2006), have been reported. For instance, the susceptibility of Norway spruce to Ceratocystis polonica has been shown to be under strong genetic control (Brignolas et al 1998;Evensen et al 2000).…”

Leaf litter decomposition differs among genotypes in a local Betula pendula population

“…B. pendula is a predominantly sexual species, but genotypes can be multiplied by micropropagation for study purposes or plantations. The B. pendula saplings used in this study were cloned from parental trees during spring 1998 (for micropropagation protocol see Laitinen et al 2004Laitinen et al , 2005 and planted at the growing site in June 1999. The growing site (61°47ЈN, 29°21ЈE) is an abandoned cultivated Weld with a Wne sandy till soil (Laitinen et al 2005).…”

Age-Related Shifts in Leaf Chemistry of Clonal Aspen (Populus tremuloides)

“…Within-plant differences in chemical defense can occur as a result of induction (Karban and Baldwin, 1997), leaf maturation (Lindroth et al, 1987;Riipi et al, 2002), somatic mutations in meristematic tissues (Suomela and Ayres, 1994;Gill et al, 1995;Tuskan et al, 1996), and through the process of ontogenetic maturation from juvenile to adult phase (Bryant and Julkunen-Tiitto, 1995;Karban and Thaler, 1999;Erwin et al, 2001;Boege and Marquis, 2005;Laitinen et al, 2005. Within-species variation in plant chemistry can affect ecological interactions and ecosystem processes. For example, primary plant compounds such as protein and water are critical for herbivore growth and development (Awmack and Leather, 2002), and qualitative or quantitative variation in phytochemical defenses within a species also strongly influences herbivore behavior and performance (Crawley, 1983;Schultz, 1988;Shelton, 2000).…”

“…Whereas relatively little is known about the effects of development on the chemical content of plants, many studies have found that developmentally based variation can significantly influence herbivore behavior and performance (Kearsley and Whitham, 1989;Swihart and Bryant, 2001;Lawrence et al, 2003). Studies that have measured within-year and between-year (Bryant and Julkunen-Tiitto, 1995;Erwin et al, 2001;Boege and Marquis, 2005;Laitinen et al, 2005) developmentally mediated changes in plant chemistry indicate that such changes can be significant and suggest that these chemical shifts are likely to be ecologically important.…”