Phenylalanine Ammonia-Lyase (PAL) and Cinnamate 4-hydroxylase (C4H) and Catechins (flavan-3-ols) Accumulation in Tea

Funct Integr Genomics. 2009 Feb;9(1):125-34. doi: 10.1007/s10142-008-0092-9. Epub 2008 Aug 5.


Phenylalanine ammonia-lyase and cinnamate 4-hydroxylase are important enzymes in allocating significant amounts of carbon from phenylalanine into the biosynthesis of several important secondary metabolites. Tea is an important crop of commerce known for its beverage and medicinally important flavonoid compounds, mainly catechins. As metabolic flux for the operation of the flavonoid pathway is maintained through the activities of PAL and C4H, thus, catechins biosynthesis in tea is critically dependent on the products of these enzymes. We examined the expression of PAL and C4H. Sequence encoding CsPAL was isolated from tea by polymerase chain reaction using sequence information available at the NCBI GenBank. Sequence encoding C4H was isolated from tea by using differential display of mRNA and rapid amplification of cDNA ends technology. CsC4H (AY641731) comprised of 1,352 bp full-length cDNA with open reading frame of 1,173 bp encoding 390 amino acids. Catechin contents decreased in response to drought stress (DS), abscisic acid (ABA), and gibberellic acid (GA(3)) treatments but increased in response to wounding. The expression of CsPAL and CsC4H showed the same behavior under the above treatments and was also in accordance with the catechin contents. A positive correlation between catechin contents and gene expression suggested a critical role of the enzymes in catechins biosynthesis and a crosstalk between phenylpropanoid and flavonoid pathways.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Abscisic Acid / pharmacology
  • Blotting, Northern
  • Camellia sinensis / drug effects
  • Camellia sinensis / enzymology*
  • Camellia sinensis / genetics
  • Catechin / metabolism*
  • Droughts
  • Gene Expression Regulation, Plant / drug effects
  • Gibberellins / pharmacology
  • Phenylalanine Ammonia-Lyase / genetics
  • Phenylalanine Ammonia-Lyase / metabolism*
  • Plant Leaves / drug effects
  • Plant Leaves / enzymology
  • Plant Leaves / genetics
  • Tea / drug effects
  • Tea / enzymology*
  • Tea / genetics
  • Time Factors
  • Trans-Cinnamate 4-Monooxygenase / genetics
  • Trans-Cinnamate 4-Monooxygenase / metabolism*


  • Gibberellins
  • Tea
  • Abscisic Acid
  • Catechin
  • Trans-Cinnamate 4-Monooxygenase
  • Phenylalanine Ammonia-Lyase