Previous investigations of the expression of JIP genes (jasmonate-induced protein) from barley were related only to the induction upon exogenous application of jasmonate or abscisic acid or the influence of environmental stresses e.g. desiccation or osmotic stress. A phenotypic/physiological role of jasmonates in plant growth and development was observed for several times without a molecular explanation. The molecular analysis of the effect of jasmonates in the development of barley is the item of this work. JIP23 (jasmonate-induced protein, 23 kDa) was used as a reporter. Jip expression in the development of barley was analysed by Northern blots, Western blots and by in situ hybridization and immunocytochemically at tissue sections. During seed development a jip23 expression was found, but in dry seeds transcript and protein were no longer detectable. In growing seedlings was found a tissue- and cell type-specific jip23 expression. Transcript and protein were detectable in companion cells of the phloem, above all in the mesokotyl, and in all cells of the scutellum. A time and local change of the jip23 expression during seedling development has been shown. No indications of function for JIP23 could be drawn from sequence comparisons in the data bases previously. Therefore the analysis of time and local specific expression and analysis of compartmentation of the isoforms of JIP23 was done in order to derive indications of function for this protein. For that purpose additional methods (isolation of cell nuclei, extraction of proteins, 1- and 2-dimensional separations of proteins) were used. There are only insignificant differences between the isoforms of JIP23 in seedlings and in jasmonate-treated leaves. Therefore a marked functional difference of the isoforms in seedlings or jasmonate-treated leaves is improbable. An increased occurence of several isoforms in the nucleus of jasmonate-treated leaves suggests, that the isoforms might have different functions within the compartments of the cell. Two functions will be discussed for JIP23. The occurence in tissues, which serve for the transport of osmotically active nutrients from endosperm to seedling (scutellum, phloem) suggests, that JIP23 might have a protective function during osmotic stress. Beyond that JIP23 might interfere with the accumulation of the photosynthetic apparatus, because it accumulates in tissues which are photosynthetic inactive. It was shown, that jip23 expression during development in cereals is not cultivar- or species-specific. Jip23 expression takes place in jasmonate-treated leaves from cultivar "Salome" but not in leaves from cultivar "Gerbel". In the genome from cultivar "Gerbel" a gene which codes for JIP23 was detected and is expressed during seedling development. Besides this the occurence of at least two genes for JIP23 in the genome of cultivar "Salome" suggests, that JIP23 genes might be induced differentially in jasmonate-treated leaves and seedlings. In barley leaves the jip23 expression is dependent on jasmonates. Therefore it was investigated, if in seedlings a endogenous increase of jasmonates can induce the synthesis of JIP23. No clear correlation was found between the accumulation of JIP23-transcript and the contents of jasmonates. Under disdussion is the induction of the JIP23 genes in the seedling, independent on jasmonate or not alone dependent on jasmonate.