Inhibition of the gravitropic bending response of flowering shoots by salicylic acid.
The upward gravitropic bending of cut snapdragon, lupinus and anemone flowering shoots was inhibited by salicylic acid (SA) applied at 0.5 mM and above. This effect was probably not due to acidification of the cytoplasm, since other weak acids did not inhibit bending of snapdragon shoots. In order to study its mode of inhibitory action, we have examined in cut snapdragon shoots the effect of SA on three processes of the gravity-signaling pathway, including: amyloplast sedimentation, formation of ethylene gradient across the stem, and differential growth response. The results show that 1 mM SA inhibited differential ethylene production rates across the horizontal stem and the gravity-induced growth, without significantly inhibiting vertical growth or amyloplast sedimentation following horizontal placement. However, 5 mM SA inhibited all three gravity-induced processes, as well as the growth of vertical shoots, while increasing flower wilting. It may, therefore, be concluded that SA inhibits bending of various cut flowering shoots in a concentration-dependent manner. Thus, at a low concentration SA exerts its effect in snapdragon shoots by inhibiting processes operating downstream to stimulus sensing exerted by amyloplast sedimentation. At a higher concentration SA inhibits bending probably by exerting general negative effects on various cellular processes.
Friedman
Haya
H
Department of Postharvest Science of Fresh Produce, The Volcani Center, Agricultural Research Organization, Bet Dagan, Israel.
Meir
Shimon
S
Halevy
Abraham H
AH
Philosoph-Hadas
Sonia
S
D019342:Acetic Acid / Q000494:pharmacology; D031883:Anemone / Q000187:drug effects / Q000254:growth & development; D032161:Antirrhinum / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D002614:Chelating Agents / Q000494:pharmacology; D019343:Citric Acid / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005030:Ethylenes / Q000378:metabolism; D035264:Flowers / Q000187:drug effects / Q000254:growth & development; D005561:Formates / Q000494:pharmacology; D006112:Gravitation; D018522:Gravitropism / Q000187:drug effects*; D031297:Lupinus / Q000187:drug effects / Q000254:growth & development; D010937:Plant Growth Regulators / Q000378:metabolism; D018520:Plant Shoots / Q000187:drug effects* / Q000254:growth & development*; D018087:Plastids / Q000187:drug effects; D031947:Ranunculus / Q000187:drug effects / Q000254:growth & development; D020156:Salicylic Acid / Q000494:pharmacology*
D002614:Chelating Agents; D005030:Ethylenes; D005561:Formates; D010937:Plant Growth Regulators; C030544:formic acid; D019343:Citric Acid; C036216:ethylene; D020156:Salicylic Acid; D019342:Acetic Acid