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PAL inhibitor evokes different responses in two Hypericum species
Bořivoj Klejdus1, Jozef Kováčik, Petr Babula
1Institute of Chemistry and Biochemistry, Faculty of Agronomy, Mendel University in Brno, Zemědělská 1, 613 00 Brno, Czech Republic.
Plant Physiology and Biochemistry : PPB
|December 21, 2012
Summary
Inhibiting phenylalanine ammonia-lyase (PAL) in Hypericum species affected secondary metabolite accumulation. Hypericum perforatum showed growth reduction and altered hypericins/hyperforin, unlike Hypericum canariense.
Area of Science:
- Plant biochemistry
- Secondary metabolite biosynthesis
- Plant physiology
Background:
- Hypericum species are known for accumulating valuable secondary metabolites.
- The phenylpropanoid pathway, initiated by phenylalanine ammonia-lyase (PAL), is crucial for producing these compounds.
- Understanding how PAL inhibition affects metabolite profiles is key to metabolic engineering and drug discovery.
Purpose of the Study:
- To investigate the impact of phenylalanine ammonia-lyase (PAL) inhibition on secondary metabolite accumulation in Hypericum perforatum and Hypericum canariense.
- To compare the responses of these two Hypericum species to PAL inhibition.
- To explore potential compensatory mechanisms and anatomical changes following PAL inhibition.
Main Methods:
- Application of 2-aminoindane-2-phosphonic acid (AIP), a PAL inhibitor, to shoots of H. perforatum and H. canariense.
- Measurement of PAL activity, soluble phenols, phenolic acids, hypericins, and hyperforin content.
- Analysis of growth depression, proline levels, and secondary xylem formation via microscopy.
Main Results:
- H. perforatum exhibited significant growth depression, PAL inhibition (-60%), decreased phenols, and altered hypericins/hyperforin levels (decreased hypericins, increased hyperforin) upon AIP treatment.
- H. canariense showed less pronounced growth changes, with PAL activity restoration (+330%) and increased flavonoids, while hypericins and hyperforin were significantly lower than in H. perforatum.
- Increased proline in H. perforatum suggested a compensatory antioxidative response, and microscopy revealed species-specific differences in secondary xylem formation and lignification.
Conclusions:
- PAL inhibition differentially impacts secondary metabolism and growth in H. perforatum and H. canariense.
- H. perforatum is more sensitive to PAL inhibition, leading to significant metabolic and growth alterations.
- H. canariense demonstrates a more resilient response, with potential for compensatory mechanisms and distinct anatomical adaptations.
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