Dubas, E., Wędzony, M., Petrovska, B., Salaj, J., and Żur, I.
ACTA BIOLOGICA CRACOVIENSIA Series Botanica
Androgenesis, microspores, triticale, cytoskeleton, microtubules
Upon stress treatment, isolated microspores of triticale (×Triticosecale Wittm.) were directed towards sporophytic
development (androgenesis). We used fluorescence microscopy to study the cell structural reorganization
associated with the process. Changes in the developmental pathway coincided with the character of the microtubular
cytoskeleton configuration, the number and direction of nuclear divisions, changes in vacuolization, the
distribution of mitochondria, ER and starch grains, and the architecture of new cell wall formation. A band of
diffused fluorescence surrounding the nucleus was observed before the first symmetric division of microspores.
This structure most likely represents a preprophase band (PPB). Successive mitotic divisions within the
microspore wall led to the formation of multinucleate or multicellular structures consisting of one or two
domains of cells differing in size. They were later released from the sporoderm and continued further development
with features typical for a monocotyledonous embryo. The pattern of internal architecture of androgenic
structures depended on their developmental phase. Before and after release from the microspore wall, cortical
microtubules (MTs) exhibited various configurations without preferential orientation. They formed a denser network
in the region opposite to the sporoderm rupture site. Released multicellular structures showed both
intensely fluorescing cortical MTs and more dispersed endoplasmic MTs radiating along the cytoplasmic strands
from the nuclear region to the cell cortex. Up to globular stage, isotropically expanding cells of androgenic
embryos showed a random pattern of MTs. This is the first report that successive events of androgenic development
of triticale microspores are associated with MT reorganization. The results support the view that
changes in cytoskeleton architecture are critical during induction of androgenesis.
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