Effect of feeding precursors on phenylalanine ammonia-lyase activity and coumarin accumulation in leaves of <Emphasis Type="Italic">Matricaria chamomilla</Emphasis> L. |
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Authors: | Jozef Ková?ik Ivan Kron Miroslav Rep?ák Martin Ba?kor |
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Institution: | (1) Department of Botany, Institute of Biology & Ecology, Faculty of Science, P. J. Šafárik University, Mánesova 23, 041 67 Košice, Slovak Republic;(2) Institute of Medical Chemistry, Biochemistry & Clinical Biochemistry, Faculty of Medicine, P. J. Šafárik University, Tr. SNP 1, 040 66 Košice, Slovak Republic |
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Abstract: | Four-week-old chamomile (Matricaria chamomilla) plants were exposed for 72 h to 0.01, 0.1 and 1 mM phenylalanine (Phe) or tyrosine (Tyr). Phe at all concentrations significantly
increased phenylalanine ammonia-lyase (PAL) activity (by 30, 76 and 90%, respectively) as well as accumulation of coumarin-related
compounds (herniarin and its precursors (Z)- and (E)-2-β-D-glucopyranosyloxy-4-methoxycinnamic acids). Free Phe content increased significantly at the highest dose tested. Lower
Tyr concentrations (0.01 and 0.1 mM) significantly increased PAL activity and increased free Tyr content, however free Phe
content decreased. This indicated that Tyr-mediated stimulation of PAL is coupled to Phe consumption. Notwithstanding, Tyr
had no effect on coumarin accumulation. Therefore we speculate that in chamomile a regulation/signalling mechanism could be
operating in the pathway leading to coumarin synthesis. The malondialdehyde accumulation, an usual marker of stress in plants,
was not significantly changed by amino acid supplements, suggesting that membrane damage is not the signal causing coumarin
accumulation. In parallel experiment we observed that neither lower (0.25 × full strength), nor higher (3 × full strength)
nitrogen concentration of nutrient solution compared to normal (1 × full strength, 205 mg N l-1) solution used for Phe/Tyr supply affected herniarin and GMCAs accumulation. This indicates that Phe had stimulatory effect
on PAL activity and coumarin metabolism. |
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Keywords: | Coumarins Lipid peroxidation Matricaria chamomilla Phenylalanine Phenylalanine ammonia-lyase Tyrosine |
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