Plant Growth Regulation

, Volume 49, Issue 2, pp 137–146

Enhancement of phenylpropanoid enzymes and lignin in Phalaenopsis orchid and their influence on plant acclimatisation at different levels of photosynthetic photon flux

  • Mohammad Babar Ali
  • Serida Khatun
  • Eun-Joo Hahn
  • Kee-Yoeup Paek
Original Paper

DOI: 10.1007/s10725-006-9003-z

Cite this article as:
Ali, M.B., Khatun, S., Hahn, E. et al. Plant Growth Regul (2006) 49: 137. doi:10.1007/s10725-006-9003-z

Abstract

Effects of three levels of photosynthetic photon flux (PPF: 60, 160 and 300 µmol m−2s−1) were investigated in one-month-old Phalaenopsis plantlets acclimatised ex vitro. Optimal growth, chlorophyll and carotenoid concentations, and a high carotenoid:chlorophyll a ratio were obtained at 160 µmol m−2s−1, while net CO2 assimilation (A), stomatal conductance (g), transpiration rate (E) and leaf temperature peaked at 300 µmol m−2s−1, indicating the ability of the plants to grow ex vitro. Adverse effects of the highest PPF were reflected in loss of chlorophyll, biomass, non-protein thiol and cysteine, but increased proline. After acclimatisation, glucose-6-phosphate dehydrogenase, shikimate dehydrogenase, phenylalanine ammonia-lyase (PAL) and cinnamyl alcohol dehydrogenase (CAD) increased, as did lignin. Peroxidases (POD), which play an important role in lignin synthesis, were induced in acclimatised plants. Polyphenol oxidase (PPO) and β-glucosidase (β-GS) activities increased to a maximum in acclimatised plants at 300 µmol m−2s−1. A positive correlation between PAL, CAD activity and lignin concentration was observed, especially at 160 and 300 µmol m−2s−1. The study concludes that enhancement of lignin biosynthesis probably not only adds rigidity to plant cell walls but also induces defence against radiation stress. A PPF of 160 µmol m−2s−1was suitable for acclimatisation when plants were transferred from in vitro conditions.

Keywords

AcclimatisationLigninPhalaenopsisPhenylpropanoid enzymesProline

Abbreviations

CA-POD

Caffeic acid peroxidase

CGA-POD

Chlorogenic acid peroxidase

CAD

Cinnamyl alcohol dehydrogenase

DNPH

2,4-dinitrophenylhydrazine

G6PDH

Glucose 6 phosphate dehydrogenase

(β-GS)

β-glucosidase

NPSH

Non-protein thiol

PMSF

Phenylmethyl sulfonyl fluoride

PVPP

Polyvinyl polypyrrolidone

SKDH

Shikimate dehydrogenase

PAL

Phenylalanine ammonia lyase

PPF

Photosynthetic photon flux

PPO

Polyphenol oxidase

Copyright information

© Springer Science+Business Media B.V. 2006

Authors and Affiliations

  • Mohammad Babar Ali
    • 1
  • Serida Khatun
    • 2
  • Eun-Joo Hahn
    • 2
  • Kee-Yoeup Paek
    • 2
  1. 1.National Food Research Institute Food Biotechnology DivisionMetabolic Regulation LaboratoryTsukuba, IbarakiJapan
  2. 2.Research Center for the Development of Advanced Horticultural TechnologyChungbuk National UniversityCheong-juRepublic of Korea