An mRNA of tobacco cell, which is rapidly inducible by methyl jasmonate in the presence of cycloheximide, codes for a putative glycosyltransferase.

Two-dimensional gel electrophoretic display of polypeptides labeled in vivo and those synthesized in vitro from poly(A)(+)-RNA indicated that treatment of cultured cells of tobacco (Nicotiana tabacum) BY-2 with methyl jasmonate (MeJA) induces accumulation of a limited number of specific mRNAs within a few hours. The MeJA-induction of most of these mRNAs was inhibited by cycloheximide (CHX). Six MeJA-inducible cDNAs identified by differential screening were classified into three groups based on the sensitivity of their induction to CHX. Induction of group I mRNAs by MeJA occurred earlier than the induction of other mRNAs and it was not inhibited by CHX. The induction of group II mRNAs by MeJA was blocked by CHX, while group III mRNAs were induced by CHX alone. One group I cDNA was found to encode a putative protein, JIGT, homologous to UDP-sugar glycosyltransferases previously characterized from several plant species. JIGT was structurally different from a putative glycosyltransferase that is rapidly inducible by salycylic acid (SA) in BY-2 cells. JIGT mRNA was not induced by SA. In addition to MeJA, as little as 10(-9) M coronatine induced JIGT mRNA. A sequence highly homologous to JIGT is present as a single copy in the genomes of Nicotiana sylvestris and N. tomentosiformis. The MeJA-inducible production of JIGT may be involved in sugar-conjugation of an unknown substrate in a defensive response and expression of the gene for JIGT in BY-2 cells might serve as a good model system for disecting molecular events occurring in JA-inducible gene expression.