Daily and infradian rhythms of circumnutation intensity in Helianthus annuus

Abstract

Circumnutation in Helianthus annuus L. was investigated by measurements lasting 4-7 weeks using a picture analysis system. The rhythmicity of circumnutation vigour (intensity) with regard to the trajectory length and period of individual circumnutations were examined. Three photoperiod conditions were applied [light/dark (LD), continuous light (LL) and LD followed by LL]. Data were processed by the Fourier analysis. Statistical analysis included the examination of circumnutation mean frequencies and correlation tests. Both parameters, trajectory length and period, revealed a daily (24 h) modulation in LD with a weak correlation between them, whereas in LL no daily modulation of the parameters was observed. After LD-LL transition, the parameters were gradually losing their daily modulation. Despite a very strong modulation of the trajectory length in LD, the period was quite stable in all groups tested, but only in LD were there no statistical differences in the number of circumnutations per 24 h among the plants studied. LD was concluded to be the strong synchronizer, making the plants circumnutate regularly. Regardless of the presence or absence of daily modulation, the infradian (several and more days long) harmonics of the trajectory length were the same in each group. These findings strongly support the view that circumnutation in sunflower, widely known as an ultradian rhythm, also possesses daily and infradian modulations of its intensity. To the authors' knowledge, this is the first report of circumnutation that was obtained by a picture analysis system in such a large timescale.

Circumnutation as a visible plant action and reaction

“…Also, changes in the period length in the conditions of cyclic diurnal illumination display a diurnal rhythm. 24,25 Moreover, in sunflower plants, changes of trajectory length, period and shape of circumnutations have a circadian (close to 24 h) rhythm. 26 The circadian character of circumnutations was described in the hypocotyl of Arabidopsis thaliana seedlings.…”

Spontaneous action potentials and circumnutation in Helianthus annuus

“…Spontaneous APs (SAPs) have lately been observed in Solanum lycopersicum plants (Macedo et al 2015) and in Helianthus annuus (Zawadzki et al 1995), which is also known to exhibit intense and varied endogenous movements named circumnutation (CN). CNs are commonly observed in growing plants (Darwin and Darwin 1880); they vary during different stages of plant growth, and exhibit an ultradian, daily, and circadian rhythm as well as complex geometrical patterns (Buda et al 2003;Charzewska and Zawadzki 2006). CN is an endogenous movement modulated by multiple stimuli, e.g.…”

“…CN is an endogenous movement modulated by multiple stimuli, e.g. light, wounding, touch, temperature, chemicals, and gravity (Buda et al 2003;Hayashi et al 2004;Charzewska and Zawadzki 2006;Stolarz et al 2010). The same stimuli also trigger APs, as mentioned above; therefore, the search for relationships between endogenous CN and excitation in plants is advisable.…”

Influence of temperature on the infradian growth rhythm inUlva lactuca(Chlorophyta)

“…Various schemes have been proposed for dividing the infradian rhythms further into subgroups, such as periods of about 2 days, half a week (circasemiseptan), 1 week (circaseptan), 10 days, 14 days (circasemilunar), 1 month (circatrigintan), 1 year (circannual), and even longer (Reinberg & Smolensky, 1983;Spruyt et al, 1987;Yamashita et al, 1999;Chumakov et al, 2000;Buda et al, 2003;Halberg et al, 2003;Vignoles et al, 2006).…”

“…There are also some reports of infradian rhythms in higher plants; clear examples are the description of circaseptan rhythms of water uptake in Phaseolus vulgaris seeds (Spruyt et al, 1987) and circumnutation intensity in Helianthus annuus (Buda et al, 2003). However, information about such infradian rhythms in seaweeds is sparse and the majority of reports concern reproduction.…”