p-Coumarate:CoA ligase as a key gene in the yield of catechins in tea [Camellia sinensis (L.) O. Kuntze]
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Tea is an important crop known for its beverage and antioxidant polyphenols—catechins and its derivatives. Catechins are synthesized through flavonoid (FL) pathway and stored in the vacuole. A metabolic flux for the operation of FL pathway is maintained through the supply of 4-coumaroyl-CoA of phenylpropanoid pathway. 4-Coumaroyl-CoA is synthesized through the catalytic activity of p-coumarate:CoA ligase (4CL) using 4-coumaric acid and acetyl-CoA as the substrates. The present manuscript reports the full-length cDNA cloning of 4CL from tea (Cs4CL accession number DQ194356) and its association with catechin yield. Cs4CL comprised of 2,165 bp with an open reading frame (ORF) of 1,764 nt, starting from 118 to 1,882 encoding 588 amino acids. Altering catechin content through a variety of environmental conditions such as drought stress (DS), abscisic acid (ABA) and gibberellic acid (GA3) treatments, and wounding established a strong positive correlation coefficient between catechins content and the expression of Cs4Cl. In addition, tea clones with high levels of catechins had higher expression of Cs4Cl whereas tea clones with lower catechins exhibited lower expression of this gene. Exposure of tea shoots to 50–100 μM catechins led to down-regulation of the expression of Cs4CL suggesting product-mediated feedback regulation and an important role for the phenylpropanoid pathway in determining catechin yield in tea.
Keywords4-Coumarate:CoA ligase Catechin Flavonoids Phenylpropanoid Tea
4-coumarate CoA ligase
rapid amplification of cDNA ends
polymerase chain reaction
Authors are thankful to the Council of Scientific and Industrial Research (CSIR), India, for funding the present research work under the New Millennium Indian Technology Leadership Initiative (NMITLI) program entitled “Using functional genomics in plants: development and use of technologies for gene discovery and expression modulation—niche pathway engineering in tea”. KS and AR are grateful to CSIR for awarding Junior/Senior Research Fellowships. PS thanks CSIR for award of project assistantship. Technical help provided by Mr. Digvijay Singh in gene sequencing is duly acknowledged.
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