INDUCTION BY METHYL JASMONATE OF EMBRYOGENESIS-RELATED PROTEINS AND MESSENGER-RNAS IN NICOTIANA-PLUMBAGINIFOLIA

Upon treatment with jasmonic acid methyl ester (methyl jasmonate, JaMe ) detached leaf segments of in vitro-regenerated plants of Nicotiana p lumbaginifolia accumulate novel abundant proteins and mRNAs. Among the m are late embryogenesis abundant (Lea) transcripts, which appear in a temporally defined manner during somatic embryogenesis and normally d o not occur in mature plant organs such as leaves or roots. To pursue this observation, the induction by methyl jasmonate of embryogenesis-r elated proteins and mRNAs in leaf and root tissues was investigated by comparing the two-dimensional patterns of in vivo- and in vitro-trans lated polypeptides. We found a selective reinduction by methyl jasmona te of several embryo-specific proteins and mRNAs, whose expression is associated with the formation of early and mature globular stages. Som e of the jasmonate-induced embryo-specific proteins were also expresse d in leaves, but not in roots, in response to abscisic acid (ABA) or o smotic stress (sorbitol) treatment, suggesting their role in osmoprote ction of leaf and embryo tissues as discussed for LEA proteins. Wester n blot analyses with polyclonal antibodies raised against jasmonate-in duced proteins (JIPs) of M(r) 23 000 from barley highlighted the tissu e-specific reappearance of a group of closely related, evolutionarily conserved embryo-specific proteins in N. plumbaginfolia leaves after J aMe, ABA and sorbitol treatment. Actin and tubulin, for which the tran script contents were estimated, increased in amount in the course of s omatic embryogenesis, but did not change in abundance under the variou s conditions of treatment. Our results imply a specific role of JaMe i n controlling gene expression during somatic embryogenesis in N. plumb aginifolia.