Publikationen - Molekulare Signalverarbeitung

Among the plant hormones jasmonic acid and related derivatives are known to mediate stress responses and several developmental processes. Biosynthesis, regulation, and metabolism of jasmonic acid in Arabidopsis thaliana are reviewed, including properties of mutants of jasmonate biosynthesis. The individual signalling properties of several jasmonates are described.

Immature scutella of barley were transformed with cDNA coding for a 13-lipoxygenase of barley (LOX-100) via particle bombardment. Regenerated plants were tested by PAT-assay, Western-analysis and PCR-screening. Immunocytochemical assay of T0 plants showed expression of the LOX cDNA both in the chloroplasts and in the cytosol, depending on the presence of the chloroplast signal peptide sequences in the cDNA. A few transgenic plants containing higher amounts of LOX-derived products have been found. These are the candidates for further analysis concerning pathogen resistance.

Treatment of barley leaf segments with jasmonic acid methyl ester (JM) leads to the accumulation of a set of newly formed abundant proteins. Among them, the most abun dant protein exhibits a molecular mass of 23 kDa (JIP‐23). Here, data are presented on the occurrence and expression of the lIP‐23 genes in different cultivars of Hordeum vulgare . Southern blot analysis of 80 cultivars revealed the occurrence of 2 to 4 genes coding for JIP‐23 in all cultivars. By means of Northern blot and immunoblot analysis it is shown that some cultivars lack the ex pression of jip‐23 upon treatment of primary leaves with JM as well as upon stress performed by incubation with 1 M sorbitol solution. During germination, however, all tested cultivars ex hibited developmental expression of jip‐23 . The results are dis cussed in terms of possible functions of JIP‐23 in barley.