Correlation between the endogenous circadian rhythmicity in growth rate and fluctuations in oleic acid content in expanding stems of Chenopodium rubrum L.

Abstract

Chenopodium rubrum L. plants exhibit an endogenous circadian rhythm in their instantaneous stem extension rate in continuous light (A. Lecharny and E. Wagner, 1984, Physiol. Plant. 60, 447-453). Stem extension rate and fatty-acid composition of two stem parts were measured in plants kept in continuous light for 90 h following a 12-h dark period. Fluctuations in the relative size of the oleic acid pool were evidenced in the stem tissues. The peaks (minima and maxima) of the oleic acid content occurred at the same times after the end of the 12-h dark periods as the peaks of the stem extension rate. This rhythmic behaviour ceased when growth was completed. No significant rhythmic changes were observed in any other fatty acid pools. Lipids in which the oleate content is rhythmically modified were exclusively phosphatidylcholine and phospha-tidylethanolamine. Thus, there was a specific correlation between the relative amount of oleic acid in phosphatidylcholine and phosphatidylethanolamine and the rate of instantaneous growth in the same tissue. The rhythmic variations in the oleic acid may be linked to the endomembrane flow in relation to the rate of growth.

Transcriptional and post-transcriptional control of the plant circadian gene regulatory network

“…Processes as diverse as stem elongation, stomatal opening and closure and many enzymatic activities are under circadian control [3][4][5][6]. Most of these rhythms are now known to be tightly linked to strong oscillations in gene expression in most organisms, a phenomenon that was first characterized at a genome-wide level in plants [7].…”

Circadian Control of cab Gene Transcription and mRNA Accumulation in Arabidopsis

“…In addition to the morphological rhythms, plants have revealed numerous circadian oscillations at the physiological and biochemical levels. Processes as diverse as stem elongation (Lecharny and Wagner, 1984;Lecharny et al, 1990), stomatal opening and closure (Gorton et al, 1989), and many specific enzyme activities (Deng et al, 1989) exhibit circadian control. In most instances, these rhythms have been shown to be reset by light, and in several cases the photoreceptor that mediates the resetting stimulus has been shown to be phytochrome (Simon et al, 1976).…”

Circadian rhythms in plants: a millennial view

“…There is a circadian rhythm in the elongation rate of the stem of Chenopodium rubrum ( Lecharny and Wagner 1984) that is correlated with a rhythm in oleic acid content ( Lecharny et al 1990). More recently, it has been shown that there is a rhythm in floral stem elongation in Arabidopsis ( Jouve et al 1998).…”