Imaging of native early embryogenic tissue of Scots pine (Pinus sylvestris L.) by ESEM

Environmental scanning electron microscopy enables the investigation of uncoated pine early embryogenic tissue samples in situ. The samples were examined under low vacuum conditions (air pressure 550 Pa) at a temperature of around -18°C by the AQUASEM II noncommercial environmental scanning electron microscope. The native extracellular matrix surface network was imaged by the environmental scanning electron microscope and in dark field mode of the optical microscope too. The backscattered electron detector disclosed brightness loci in the cells of early embryogenic culture. This work shows images of native pine embryogenic tissues. The continuity of extracellular matrix with structural integrity of plant organism is discussed

In vitro testing of defense reactions in zygotic and somatic embryos of Abies numidica

Defense of desiccated cotyledonary somatic embryos and mature zygotic embryos of Abies numidica was tested in vitro by dual cultures with tester, fungus Phaeolus schweinitzii. Both types of embryos expressed defense reactions manifested by inhibited growth of fungal tester towards the embryos. Mycelial growth was described by logistic sigmoid growth model with a single asymptote. Mutual comparisons of mycelial growth in presence of zygotic and somatic embryos showed significant differences in parameters of mycelium growth curves towards the embryos. Larger defense reactions were observed in zygotic embryos relative to somatic embryos and unlimited control cultivations without embryo. The possible role of auxin in the defense response of plant embryos is discussed