The Occurrence of Calcium Oxalate Crystals and Distribution of Arabinogalactan Proteins (AGPs) in Ovary Cells During Fragaria x ananassa (Duch.) Development

In this study, the presence of calcium oxalate crystals and distribution of arabinogalactan proteins (AGPs) in the ovary of Fragaria x ananassa (Duchesne) were investigated. The arrangement of the AGP epitopes was analyzed using immunohistochemistry techniques with JIM13, JIM15, and MAC207 monoclonal antibodies. To confirm the immunofluorescence studies, experiments at the subcellular level were performed with the immunogold method using transmission electron microscopy. We observed calcium oxalate crystals as druses in the middle layer of the ovary, which created a distinct ring-like immunofluorescence pattern around the ovule, indicating the presence of AGP epitopes. We propose hypotheses concerning the roles of calcium oxalate crystals in ovaries: the occurrence of crystals in the external part of the ovary may constitute a mechanical barrier against herbivores (1) the presence of AGPs in close proximity to calcium oxalate crystals may support their role as a calcium depository, which is important for the developing embryo and seed coat formation as well as in the interaction between pollen tubes and female gametophyte during sexual plant reproduction (2).