Light enhanced perception of gravity in stems of intact pea pisum sativum cultivar alaska seedlings
Britz, S.J.; Galston, A.W.
Planta (Heidelberg) 154(2): 189-192
ISSN/ISBN: 0032-0935 Accession: 005809892
Dark-grown, 6-day-old pea seedlings (P. sativum L. cv. Alaska) do not respond gravitropically to brief (.apprx. 3 min) horizontal presentations, but seedlings given a pulse of red light (R) 16-24 h earlier respond to such stimuli by vigorous curvature of the epicotyl. With continuous horizontal stimulation (.apprx. 100 min), the kinetics and extent of the gravitropic response are almost identical in irradiated and dark-control plants. Prior R increases graviperception without altering the rate-limiting steps underlying the generation of curvature. This effect of R on graviperception develops slowly; seedlings studied only a few hours after R show differences in the kinetics of the gravitropic response, but not in presentation time. Neither the kinetics nor the extent of gravitropic curvature should be used as criteria for establishing changes in primary processes in gravitropism.