AN MESSENGER-RNA 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 tha t treatment of cultured cells of tobacco (Nicotiana tabacum) BY-2 with methyl jasmonate (MeJA) induces accumulation of a limited number of s pecific mRNAs within a few hours, The MeJA-induction of most of these mRNAs was inhibited by cycloheximide (CHX), Six MeJA-inducible cDNAs i dentified by differential screening were classified into three groups based on the sensitivity of their induction to CHX, Induction of group I mRNAs by MeJA occured 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, O ne group I cDNA was found to encode a putative protein, JIGT, homologo us to UDP-sugar glycosyltransferases previously characterized from sev eral plant species, JIGT was structurally different from a putative gl ycosyltransferase that is rapidly inducible by salycilic acid (SA) in BY-2 cells, JIGT mRNA was not induced by SA. In addition to MeJA, as l ittle as 10(-9) M coronatine induced JIGT mRNA, A sequence highly homo logous to JIGT is present as a single copy in the genomes of Nicotiana sylvestris and N, tomentosiformis. The MeJA-inducible production of J IGT 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 m ight serve as a good model system for disecting molecular events occur ing in JA-inducible gene expression.