Rhythmicity of L‐phenylalanine ammonia‐lyase activity in Spirodela oligorrhiza. Effects of darkening, abscisic acid and 1‐amino‐2‐phenylethylphosphonic acid

Abstract

L‐Phenylalanine ammonia‐lyase (PAL; EC 4.3.1.5) in Spirodela oligorrhiza (Kurz) Hegelm. cultivated in continuous light showed ca 48‐h rhythmicity in the activity. Abscisic acid shifted the oscillation by ca 24 h. 1‐Amino‐2‐phenylethylphosphonic acid, a competitive inhibitor of the enzyme in vitro, markedly increased PAL activity in vivo and nullified the oscillation. Rhythmicity in PAL activity did not occur in darkness. Illumination was a prerequisite for maintaining high PAL activity as well as for the occurrence of the oscillations in the enzyme activity. ‘Average’enzyme activity decreased proportionally to time of cultivation of plants in the stationary culture. Transfer of the plants to fresh medium was connected with the increase of PAL activity to a maximum during the following 1‐2 days. Diurnal oscillation of PAL activity with a maximum at 1800–1900 h, dependent on the presence of glucose or sucrose in the nutrient medium, was also recorded.

Growth-Retarding Effect of 2-Aminoindan-2-phosphonic Acid on Spirodela punctata

“…Because of shortened and tough interfrond connections, the progeny fronds did not separate from the mother fronds; the AIP-treated cultures formed clusters comprised of almost all the progeny fronds. PheP was found to have a similar effect on growth (Knypl et al 1986). …”

“…The plants were grown under sterile conditions in Erlenmeyer flasks containing 20 cm 3 of the nutrient medium. The mineral medium contained 4 mM ammonium sulfate as the sole nitrogen source and 1% glucose (Knypl et al 1986). AIP (1 mM) was dissolved in deionized water, and aliquots were added to autoclaved medium to give the desired concentrations.…”

Diurnal periodicity of chalcone-synthase activity during the development of oat primary leaves

“…Furthermore, the exposure to fluctuations of ambient temperature between 12 and 30 ~ C and changes in plant nutrition should have only a small effect on the period of an endogenous circadian rhythm (Bfinning 1958;Jerebzoff 1986). Such criteria are fulfilled for the diurnal rhythms of the growth rate of Arena coleoptiles Dyke 1954, 1957) and, with respect to secondary metabolism, for the circadian rhythm of PAL activity in several plant systems (Podstolsky and Brown 1974;Gordon and Koukkari 1978;Knypl et al 1986), and of 4-coumarate :CoA ligase activity in stems of Salix babylonica; the latter rhythm is maintained in both continuous light and continuous darkness (Feutry and Letouz6 1984). No correlation seems to exist between the circadian rhythm of the growth-rate of Arena coleoptiles (c.f.…”