Control and regulation of the gravitropic response of cut flowering stems during storage and horizontal transport
S. Philosoph-Hadas, S. Meir, I. Rosenberger, A.H. Halevy
ISHS Acta Horticulturae 405: 343-350. 1995.
1995
บทคัดย่อ
One of the major postharvest problems of cut flowers with actively growing spikes is their bending as a response to gravity, mainly during horizontal transport. The possible involvement of cytosolic calcium ([Ca2]cyt) as a second messenger in this hormone-induced gravitropic bending of flower shoot regions capable of linear growth after harvest, was examined by application of various calcium-related agents. The gravitropic bending of cut Snapdragon, Eremurus, mini-gladiolus, Ornithogalum, Lupinus and Anemone was significantly inhibited by application of the Ca2+ chelators EDTA, EGTA and CDTA. While the Ca2+ chelator BAPTA inhibited equally well the bending of gravi-stimulated snapdragon and Ornithogalum spikes, the Ca2+ channel blocker LaCl3 was effective in inhibiting bending of snapdragon only, suggesting that these two cut flowers may have different modes of extruding Ca2+ outside the cytosol. Conversely, application of CaCl2 or its agonists, Bay K-8644 and A23187, stimulated their bending. The formation of curvature in snapdragon and Ornithogalum was accompanied by an asymmetric distribution of ethylene production between lower and upper longitudinally halved stem sections. Pulsing the spikes with CDTA, which inhibits bending, abolished completely this gravity-induced ethylene gradient across the stem. Ethylene inhibitors (STS, CoCl2 and NBD) were also effective in inhibiting the gravitropic response of snapdragon spikes. The results suggest that changes in [Ca2+]cyt may be involved in the mechanism of auxin action, manifested as increased ethylene production, leading to stem elongation and subsequent gravitropic bending.