Complex relationship between growth and circumnutations inHelianthus annuusstem

Abstract

The growth and circumnutation of the stem of three-week old Helianthus annuus in the 16:8 h light:dark photoperiod were monitored using an angular position-sensing transducer and a time lapse photography system. It was found that the rate of growth and circumnutation reached a high level in the dark stage; in the light stage, however, only the growth rate reached the same high level, whereas the circumnutations were weak. These results showed that in the light stage the stem circumnutation was downregulated more strongly than the growth. Short-term stem responses to darkening and illumination were a further display of the relation between growth and circumnutations. Switching off the light caused an increase in the growth and circumnutation rate. In some cases it was accompanied by changes in the rotation direction. On the other hand, switching the light on caused an immediate transient (several-minute long) decrease in the growth rate resulting in stem contraction, and this was accompanied by an almost complete pause of circumnutation. Additionally, under light, there occurred a subsequent decrease in the magnitude, disturbance of circumnutation trajectory and, in some cases, changes in the direction of rotation. The observed stem contraction and disturbance of circumnutation imply the occurrence of turgor changes in sunflower stem, which may be caused by a non-wounding, darkening or illumination stimulus. Our experiments indicate that the disturbances of the growth rate are accompanied by changes in circumnutation parameters but we have also seen that there is no simple quantitative relation between growth rate and circumnutation rate.

Lithium distinguishes between growth and circumnutation and augments glutamate-induced excitation of Helianthus annuus seedlings

“…Additionally, in Pisum sativum roots large circumnutations stopped completely although the growth was not stopped after the apex was removed (Spurny 1968). Our previous study of three-weekold sunflower showed a complex quantitative relation between the growth rate and the circumnutation rate in lightdark conditions (Stolarz et al 2008). In the present study, a similar complex relationship has been shown in constant light under Li ?…”

“…The values of the growth rate reported for Pinus silvestris hypocotyls were from 0.001 to 0.40 mm h -1 (Spurny 1975), for Helianthus annuus hypocotyls approx. 0.60 mm h -1 (Zachariassen and Johnsson 1988), and for three-week-old stems 0.06-0.36 mm h -1 (Stolarz et al 2008). For shoots of Periploca graeca (Johnsson 1979) and hypocotyls of Arabidopsis thaliana (Schuster and Engelmann 1997), the threshold for circumnutation occurrence was approximately 0.5 and 0.05 mm h -1 , respectively.…”

“…The plant endogenous movement named circumnutation is commonly considered as an inevitable consequence of organ growth (Engelmann and Johnsson 1998), but its quantitative relation to growth is still not well established (Johnsson 1997). The complex relations between circumnutation and growth have been reported for Oriza sativa (Hayashi et al 2004;Yoshihara and Iino 2005), Arabidopsis thaliana (Schuster and Engelmann 1997), Phaseolus vulgaris (Millet and Badot 1996), Periploca graeca (Johnsson 1979), and Helianthus annuus (Zachariassen and Johnsson 1988;Stolarz et al 2008). It is known that plants can grow without circumnutation but they can also grow and circumnutate simultaneously.…”

Spontaneous action potentials and circumnutation in Helianthus annuus

“…8-19 cm min -1 (Supplementary Table 2). It is known that light-off and light-on evoke CN disturbance (Stolarz et al 2008) and AP induction (Stankovic et al 1998;Stahlberg et al 2006;Król et al 2010); therefore, to exclude this stimulus and ensure constant environmental conditions, we applied continuous light to study the relation between SAPs and CN.…”

Circumnutation as a visible plant action and reaction

“…Our experiments in Helanthus annuus indicate that the disturbances of the growth rate are accompanied by changes in circumnutation parameters but we have also seen that there is no simple quantitative relation between growth rate and circumnutation rate. 43 There is a possibility of separation of growth from circumnutations. In Phaseolus, after application of LiCl, growing, although not circumnutating shoots were obtained.…”