JASMONATES INDUCE INTRACELLULAR ALKALINIZATION AND CLOSURE OF PAPHIOPEDILUM GUARD-CELLS

Jasmonates (jasmonic acid or methyl jasmonate) promote stomatal closur e in Paphiopedilum Supersuk (RHS, 1973) and P. tonsum (Rchb.f) Stein. Studies on guard cells loaded with pH dependent fluorescent dyes show that jasmonates cause intracellular alkalinization of up to 0.5 pH uni ts within 5 to 15 min. Jasmonate-induced alkalinization always precede d stomatal closure and where alkalinization was not detected no closur e occurred. Propionic acid inhibited jasmonate-induced stomatal closur e, suggesting that jasmonate-induced intracellular alkalinization is i nvolved in guard cell movements. (C) 1997 Annals of Botany Company.