Genome‐wide analysis of the structural genes regulating defense phenylpropanoid metabolism in Populus

Abstract

Summary• Salicin-based phenolic glycosides, hydroxycinnamate derivatives and flavonoidderived condensed tannins comprise up to one-third of Populus leaf dry mass. Genes regulating the abundance and chemical diversity of these substances have not been comprehensively analysed in tree species exhibiting this metabolically demanding level of phenolic metabolism.• Here, shikimate-phenylpropanoid pathway genes thought to give rise to these phenolic products were annotated from the Populus genome, their expression assessed by semiquantitative or quantitative reverse transcription polymerase chain reaction (PCR), and metabolic evidence for function presented.• Unlike Arabidopsis , Populus leaves accumulate an array of hydroxycinnamoylquinate esters, which is consistent with broadened function of the expanded hydroxycinnamoyl-CoA transferase gene family. Greater flavonoid pathway diversity is also represented, and flavonoid gene families are larger. Consistent with expanded pathway function, most of these genes were upregulated during wound-stimulated condensed tannin synthesis in leaves.• The suite of Populus genes regulating phenylpropanoid product accumulation should have important application in managing phenolic carbon pools in relation to climate change and global carbon cycling.

Arbuscular mycorrhizal fungi as a tool to ameliorate the phytoremediation potential of poplar: biochemical and molecular aspects

“…Although clonal variability was less accentuated than variability in metal accumulation capacity, AL35 stood out for its very high PA levels, with a prevalence of conjugated forms, which reached, in the case of Put, a concentration 18-fold higher than that of other clones. The prevalence of conjugated PAs relative to the free forms is consistent with the abundance of phenolic compounds in poplar tissues (Tsai et al 2006). The strong positive correlation across clones between foliar levels of PAs and root Cu concentration (R 2 = 0.79 for total PAs) suggested that Cu rather than Zn drove the longterm PA response.…”

The MYB182 Protein Down-Regulates Proanthocyanidin and Anthocyanin Biosynthesis in Poplar by Repressing Both Structural and Regulatory Flavonoid Genes

“…A number of core flavonoid enzymes were significantly downregulated, including CHS2, F3H, DFR2, and CHI2 (Table I). In poplar, F3H and CHI are both single-copy genes, while DFR exists as two isoforms; these genes are all wound stress induced and contribute to PA synthesis (Tsai et al, 2006). While we did not detect significant down-regulation of all the isoforms for the flavonoid enzymes using our cutoffs, the analysis confirms that, when overexpressed, MYB182 has repressive effects on the flavonoid pathway.…”

The obscure events contributing to the evolution of an incipient sex chromosome in Populus: a retrospective working hypothesis

“…A gas chromatography-mass spectrometry (GC-MS) analysis of the metabolomic profiles of expanding floral buds of 16 trees (12 females and 4 males) from two Populus species (Populus deltoides and Populus nigra) was conducted to determine whether secondary metabolites were correlated with gender (Table 2). Species differences in secondary metabolites of Populus are well documented Whatley 1990, 1991a, b;Greenaway et al 1989Greenaway et al , 1992Tsai et al 2006), and male and female flowers of Salix display gender-specific floral scent characteristics (Fussel et al 2007). Our analyses demonstrate metabolite differences between genders, that is, although buds of both species and both genders contain pinobanskin-3-acetate, pinobanksin-3-acetate chalcone and pinobanksin and 3-isobutanoate, the male floral buds contained very low concentrations of these metabolites.…”