Circadian Rhythmicity in the Activities of Phenylalanine Ammonia-Lyase from Lemna perpusilla and Spirodela polyrhiza

Abstract

The oscillations in phenylalanine aunnnia-lyase activity from Spirodels pelyrhiza and phenylalanine ammonia-lyase and tyrosine ammonia-lyase activities from Lemnas perpusilam disayed a circadian rhythm under continuous lght. Rhythmiclty in enzymic activity could not be detected in continuous darkness since under this condition phenylalanine ammonialyase activity remains at a fairly constantly low level. Results from our studies of the oscillatory pattern of the respective activities of phenylalanine and tyrosine ammon_a-lyase support their "inseparability."The study of biochemical oscillations, especially of enzyme systems, has become a very important area of research (11). Among the more extensively investigated examples of oscillatory or rhythmic behavior at the metabolic level are the enzymic reactions of glycolysis in yeasts (24, 26). There are examples of soluble enzyme systems in plants which exhibit rhythmicity (17,19,25), and a recent review of biological rhythms and physiological timing in plants (16) suggests that rhythms are common in plant metabolism.In the Lemnaceae, rhythmic behavior of respiratory gas exchange has received considerable attention. Uptake of 02 byLemna gibba entrained to a short day schedule displays circadian periodicity when transferred to continuous light (20). Also, a CO2 output rhythm has been identified with Lemna perpusilla (14,15) that is associated with floral induction. The enzyme L-phenylalanine ammonia-lyase (EC 4.3.1.5) catalyzes the deamination reactions in which L-phenylalanine and L-tyrosine are degraded to trans-cinnamic acid and trans-p-coumaric acid plus ammonia, respectively. These reactions represent an important metabolic sequence in plants which results in the diversion of the two amino acids from the pathways of protein synthesis into secondary metabolism with the subsequent production of metabolites such as lignins, flavonoids, tannins, and alkaloids (27). Thus, PAL4 has a pivotal role in the reactions of secondary metabolism and in this manner, is thought to exert its influence on plant growth and development (3). Since oscillations and rhythms have been associated with processes of growth and development (5) to display fluctuations in response to various environmental conditions (3), an investigation into the nature of fluctuations in PAL activity from members of the Lemnaceae during growth and development seemed appropriate. In this paper, circadian rhythmicity in the activity of PAL is described in L. perpusilla 6746 and Spirodela polyrhiza L. (Schleiden). MATERIALS AND METHODS Cultures of L. perpusilla 6746 and S. polyrhiza L. (Schleiden)were maintained axenically in 125-ml Erlenmeyer flasks containing 50 ml of 0.5-strength Hutner's medium supplemented with 1% sucrose (13). Plants were entrained on a LD 16:8 cycle (16 hr of light followed by 8 hr of darkness) at 22 to 23 C before exposure to LL or DD. The light source used during entrainment for LL was three 15-w cool-white Sylvania fluorescent lamps which provided 235 ft-c (7.4 x 1O' ergs cm-2...

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

“…Ball and Dyke 1954) and the diurnal fluctuations in CHS activity in the leaves of the same species. Moreover, the behaviour of the CHS rhythm apparently resembles that of PAL activity observed in Lemna and Spirodela plants (Gordon and Koukkari 1978), though for oat the photoperiodic preexposure needed to induce the rhythm was extremely short.…”

“…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.…”

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

“…The oscillation of PAL activity in Spirodela is dependent on continuous illumination (this statement does not exclude that the oscillation would be much more clearly expressed in plants subjected to a definite photoperiod, cf. Gordon and Koukkari 1978) as it disappears upon darkening with a concomitant decrease in the enzyme activity, which is proportional to the duration of darkening (Figs 3 and 4). This decrease could be ascribed to the fact that cell divisions in darkened Spirodela are completely blocked.…”

“…The phenomenon was described for Xanthium pennsylvanicum (Zucker 1969), Amaranthtis eaudatus and Seta vulgaris seedlings (Bopp and Meier 1973), Robinia pseudoacacia (Podstolski and Brown 1974), Helianthus annuus (Tena et ,al. 1984), barley (McClure 1974, Podstolski and Frelich 1978, and duckweeds Lemna perpusilla and Spirodela polyrhiza (Gordon and Koukkari 1978). Diiratioo of the cycle may be different: from ca 4-5 h (Podstolski and Frelich 1978) or 8 h (McClure 1974) in barley illuminated with white light or red light following the etiolation, respectively, to ca 24 h in black locust (Podstolski and Brown 1974), sunflower hypocotyls (Tena et al 1984) and duckweeds (Gordon and Koukkari 1978).…”

“…1984), barley (McClure 1974, Podstolski and Frelich 1978, and duckweeds Lemna perpusilla and Spirodela polyrhiza (Gordon and Koukkari 1978). Diiratioo of the cycle may be different: from ca 4-5 h (Podstolski and Frelich 1978) or 8 h (McClure 1974) in barley illuminated with white light or red light following the etiolation, respectively, to ca 24 h in black locust (Podstolski and Brown 1974), sunflower hypocotyls (Tena et al 1984) and duckweeds (Gordon and Koukkari 1978). Although the physiological or molecular basis for the rhytmic oscillations is obscure, some prerequisites for the occurrence of the rhythmicity have been identified.…”