salicylates and tuberonic-acid

Recently we reported that rice salicylic acid (SA) glucosyltransferase (OsSGT) is active toward 12-hydroxyjasmonic acid (tuberonic acid, TA) and that OsSGT gene expression is induced by wounding stress. Here we report that tobacco SA glucosyltransferase (NtSGT), which is thought to be an ortholog of OsSGT, is also active toward TA. Although NtSGT expression is known to be induced by biotrophic stress, it was also induced by wounding stress in the same manner as OsSGT. These results indicate that this glucosyltransferase is important not only in biotrophic stress but also for wounding stress. It was found that this enzyme is dually functional, with activity both toward TA and SA.

Topics: Acetates; Cyclopentanes; Enzyme Induction; Gene Expression Regulation, Plant; Glucosyltransferases; Mechanical Phenomena; Nicotiana; Oxylipins; Plant Diseases; RNA, Messenger; Salicylates; Signal Transduction; Stress, Physiological

Tuberonic acid (12-hydroxy epi-jasmonic acid, TA) and its glucoside (TAG) were isolated from potato leaflets (Solanumtuberosum L.) and shown to have tuber-inducing properties. The metabolism of jasmonic acid (JA) to TAG in plant leaflets, and translocation of the resulting TAG to the distal parts, was demonstrated in a previous study. It is thought that TAG generated from JA transmits a signal from the damaged parts to the undamaged parts by this mechanism. In this report, the metabolism of TA in higher plants was demonstrated using [12-(3)H]TA, and a glucosyltransferase active toward TA was purified from the rice cell cultures. The purified protein was shown to be a putative salicylic acid (SA) glucosyltransferase (OsSGT) by MALDI-TOF-MS analysis. Recombinant OsSGT obtained by overexpression in Escherichia coli was active not only toward TA but also toward SA. The OsSGT characterized in this research was not specific, but this is the first report of a glucosyltransferase active toward TA. mRNA expressional analysis of OsSGT and quantification of TA, TAG, SA and SAG after mechanical wounding indicated that OsSGT is involved in the wounding response. These results demonstrated a crucial role for TAG not only in potato tuber formation, but also in the stress response in plants and that the SA glucosyltransferase can work for TA glucosylation.

Topics: Acetates; Cell Line; Cloning, Molecular; Cyclopentanes; DNA, Complementary; Gene Expression Regulation, Plant; Glucosides; Glucosyltransferases; Molecular Structure; Oryza; Plant Diseases; Plant Proteins; Recombinant Proteins; Reverse Transcriptase Polymerase Chain Reaction; Salicylates; Solanum tuberosum; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization