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A comparative analysis of phenylpropanoid metabolism, N utilization, and carbon partitioning in fast- and slow-growing Populus hybrid clones.

Harding SA, Jarvie MM, Lindroth RL, Tsai CJ - J. Exp. Bot. (2009)

Bottom Line: Carbon partitioning within phenylpropanoid and carbohydrate networks in developing stems differed sharply between clones.The results did not support the idea that foliar production of phenylpropanoid defence chemicals was the primary cause of reduced plant growth in the slow-growing clone.The findings are discussed in the context of metabolic mechanism(s) which may contribute to reduced N delivery from roots to leaves, thereby compromising tree growth and promoting leaf phenolic accrual in the slow-growing clone.

View Article: PubMed Central - PubMed

Affiliation: School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602, USA. sharding@uga.edu

ABSTRACT
The biosynthetic costs of phenylpropanoid-derived condensed tannins (CTs) and phenolic glycosides (PGs) are substantial. However, despite reports of negative correlations between leaf phenolic content and growth of Populus, it remains unclear whether or how foliar biosynthesis of CT/PG interferes with tree growth. A comparison was made of carbon partitioning and N content in developmentally staged leaves, stems, and roots of two closely related Populus hybrid genotypes. The genotypes were selected as two of the most phytochemically divergent from a series of seven previously analysed clones that exhibit a range of height growth rates and foliar amino acid, CT, and PG concentrations. The objective was to analyse the relationship between leaf phenolic content and plant growth, using whole-plant carbon partitioning and N distribution data from the two divergent clones. Total N as a percentage of tissue dry mass was comparatively low, and CT and PG accrual comparatively high in leaves of the slow-growing clone. Phenylpropanoid accrual and N content were comparatively high in stems of the slow-growing clone. Carbon partitioning within phenylpropanoid and carbohydrate networks in developing stems differed sharply between clones. The results did not support the idea that foliar production of phenylpropanoid defence chemicals was the primary cause of reduced plant growth in the slow-growing clone. The findings are discussed in the context of metabolic mechanism(s) which may contribute to reduced N delivery from roots to leaves, thereby compromising tree growth and promoting leaf phenolic accrual in the slow-growing clone.

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Lignin and cellulose concentrations in root fractions. (A) Klason lignin of elongating and coarse root fractions and (B) ADF cellulose of elongating and coarse root fractions (both in % dry weight). Histogram means and SD were determined from n=14–15 replicates. The two-sample t-test was used to determine significance of differences between clone means, indicated by asterisks above the SG histogram bars (**P <0.01; ***P <0.001).
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fig7: Lignin and cellulose concentrations in root fractions. (A) Klason lignin of elongating and coarse root fractions and (B) ADF cellulose of elongating and coarse root fractions (both in % dry weight). Histogram means and SD were determined from n=14–15 replicates. The two-sample t-test was used to determine significance of differences between clone means, indicated by asterisks above the SG histogram bars (**P <0.01; ***P <0.001).

Mentions: At all internodes analysed, cellulose was more abundant than lignin, and exhibited a more uniform accrual trajectory than did lignin (Fig. 4B). However, cellulose content was substantially lower in stem internodes of SG compared with FG. Of potential relevance to cellulose biosynthesis and accrual was the observation that starch concentrations were higher in stems and leaves of SG than FG (Fig. 3). Leaf tissues were used to investigate the possibility of a clonal difference in the metabolic relationship between starch and cellulose biosynthesis (Fig. 6). Due to sample limitation (see Materials and methods), leaf tissues, but not stem tissues, offered sufficient replication to conduct the correlation analysis. Strong individual plant entrainment of starch metabolism throughout leaf expansion was observed in both clones (Fig. 6). Source leaf starch and cellulose content were negatively correlated in FG (–0.908) but not in SG (Table 2). Clonal differentials in cellulose, lignin, and NSP were smaller in roots than in shoots (Figs 2, 7). A large increase in cellulose and a decrease in starch during the maturation of elongating into coarse roots were observed in both clones (Figs 3, 7).


A comparative analysis of phenylpropanoid metabolism, N utilization, and carbon partitioning in fast- and slow-growing Populus hybrid clones.

Harding SA, Jarvie MM, Lindroth RL, Tsai CJ - J. Exp. Bot. (2009)

Lignin and cellulose concentrations in root fractions. (A) Klason lignin of elongating and coarse root fractions and (B) ADF cellulose of elongating and coarse root fractions (both in % dry weight). Histogram means and SD were determined from n=14–15 replicates. The two-sample t-test was used to determine significance of differences between clone means, indicated by asterisks above the SG histogram bars (**P <0.01; ***P <0.001).
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2724693&req=5

fig7: Lignin and cellulose concentrations in root fractions. (A) Klason lignin of elongating and coarse root fractions and (B) ADF cellulose of elongating and coarse root fractions (both in % dry weight). Histogram means and SD were determined from n=14–15 replicates. The two-sample t-test was used to determine significance of differences between clone means, indicated by asterisks above the SG histogram bars (**P <0.01; ***P <0.001).
Mentions: At all internodes analysed, cellulose was more abundant than lignin, and exhibited a more uniform accrual trajectory than did lignin (Fig. 4B). However, cellulose content was substantially lower in stem internodes of SG compared with FG. Of potential relevance to cellulose biosynthesis and accrual was the observation that starch concentrations were higher in stems and leaves of SG than FG (Fig. 3). Leaf tissues were used to investigate the possibility of a clonal difference in the metabolic relationship between starch and cellulose biosynthesis (Fig. 6). Due to sample limitation (see Materials and methods), leaf tissues, but not stem tissues, offered sufficient replication to conduct the correlation analysis. Strong individual plant entrainment of starch metabolism throughout leaf expansion was observed in both clones (Fig. 6). Source leaf starch and cellulose content were negatively correlated in FG (–0.908) but not in SG (Table 2). Clonal differentials in cellulose, lignin, and NSP were smaller in roots than in shoots (Figs 2, 7). A large increase in cellulose and a decrease in starch during the maturation of elongating into coarse roots were observed in both clones (Figs 3, 7).

Bottom Line: Carbon partitioning within phenylpropanoid and carbohydrate networks in developing stems differed sharply between clones.The results did not support the idea that foliar production of phenylpropanoid defence chemicals was the primary cause of reduced plant growth in the slow-growing clone.The findings are discussed in the context of metabolic mechanism(s) which may contribute to reduced N delivery from roots to leaves, thereby compromising tree growth and promoting leaf phenolic accrual in the slow-growing clone.

View Article: PubMed Central - PubMed

Affiliation: School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602, USA. sharding@uga.edu

ABSTRACT
The biosynthetic costs of phenylpropanoid-derived condensed tannins (CTs) and phenolic glycosides (PGs) are substantial. However, despite reports of negative correlations between leaf phenolic content and growth of Populus, it remains unclear whether or how foliar biosynthesis of CT/PG interferes with tree growth. A comparison was made of carbon partitioning and N content in developmentally staged leaves, stems, and roots of two closely related Populus hybrid genotypes. The genotypes were selected as two of the most phytochemically divergent from a series of seven previously analysed clones that exhibit a range of height growth rates and foliar amino acid, CT, and PG concentrations. The objective was to analyse the relationship between leaf phenolic content and plant growth, using whole-plant carbon partitioning and N distribution data from the two divergent clones. Total N as a percentage of tissue dry mass was comparatively low, and CT and PG accrual comparatively high in leaves of the slow-growing clone. Phenylpropanoid accrual and N content were comparatively high in stems of the slow-growing clone. Carbon partitioning within phenylpropanoid and carbohydrate networks in developing stems differed sharply between clones. The results did not support the idea that foliar production of phenylpropanoid defence chemicals was the primary cause of reduced plant growth in the slow-growing clone. The findings are discussed in the context of metabolic mechanism(s) which may contribute to reduced N delivery from roots to leaves, thereby compromising tree growth and promoting leaf phenolic accrual in the slow-growing clone.

Show MeSH