Cell Structural Reorganization During Induction of Androgenesis in Isolated Microspore Cultures of Triticale (xTriticosecale Wittm.)

Abstract

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.K Ke ey y w wo or rd ds s: : Androgenesis, microspores, triticale, cytoskeleton, microtubules.

Antioxidant activity and ROS tolerance in triticale (×Triticosecale Wittm.) anthers affect the efficiency of microspore embryogenesis

“…It has been observed that upon stress treatment, embryogenic microspores swell and rearrange their cytoskeleton forming so-called SLSs, with the nucleus moved to a central position, fragmented vacuole and cytoplasmic strands connecting the perinuclear cytoplasm with the subcortical cytoplasm (Touraev et al 1997). Such changes are characteristic for various plant species, including tobacco, oilseed rape, wheat, rice and triticale (Touraev et al 1997;Dubas et al 2010). Although LT treatment increased the efficiency of ME in almost all studied triticale lines, it was not a prerequisite for ME initiation.…”

Characterization of polarity development through 2- and 3-D imaging during the initial phase of microspore embryogenesis in Brassica napus L

“…Changes in the MT cytoskeleton configuration clearly coincided with successive nuclear divisions, which led finally to multicellular ELSs formation (Simmonds and Keller 1999; Dubas et al 2010). …”

Failure of androgenesis in Miscanthus × giganteus in vitro culture of cytologically unbalanced microspores

“…Heat shock has been an effective trigger of androgenesis in wheat (Mejza et al 1993; Touraev et al 1996; Hu and Kasha 1999), maize (Genovesi 1990) and rice (Reddy et al 1985). According to the literature, the most effective treatment to change the microspore developmental pathway is a combination of temperature shock and osmotic/starvation stress achieved by high mannitol concentration of the medium (Ziauddin et al 1990; Hoekstra et al 1993; Touraev et al 1996; Kasha et al 2001; Zheng et al 2001; Liu et al 2002; Cistué et al 2003; Wędzony et al 2009; Zur et al 2008, 2009; Dubas et al 2010). Stress can be applied during various phases: to donor plants, harvested inflorescences, isolated anthers or microspores.…”