Immunolocalization of Defence-related Proteins in the Floral Organs of Barley (Hordeum vulgare L.)

We have investigated the localization of some pathogenesis- related (PR) proteins in the floral organs of barley (Hordeum vulgare L.) during the flower development using immunohistochemistry and immunocytochemistry. At a premature stage, where the different parts of the flower are not yet developed, almost no labelling of PR-1 and PR-2 was observed, whereas some weak labelling of PR-3 and PR-5 was found. At a stage where the styles had developed and diverged, and the stamens were clearly developed, a strong labelling of PR-3 was found. The strongest labelling was in the transmitting tissue of the inner part of the style but also in the stigmal branches. The label was located to the cell walls. At this stage some labelling of PR-1, PR-2 and PR-5 was found in the anther tissue. At later developmental stages, with fully developed ovary and degenerating stigmal branches, the labelling of PR-3 had significantly decreased. However, accumulation of PR-1, PR-2 and PR-5 was evident mainly in the stigmal branches but also in the stigma and occasionally in the style and ovary wall. No labelling was found inside the ovary. The spatial and temporal accumulation of the different PR proteins are discussed in relation to putative roles in defence against pathogens and in guidance and facilitation of the pollen tube growth through the style