Microtubule configurations and nuclear DNA synthesis during initiation of suspensor-bearing embryos from Brassica napus cv. Topas microspores

In the new Brassica napus microspore culture system, wherein embryos with suspensors are formed, ab initio mimics zygotic embryogenesis. The system provides a powerful in vitro tool for studying the diverse developmental processes that take place during early stages of plant embryogenesis. Here, we studied in this new culture system both the temporal and spatial distribution of nuclear DNA synthesis places and the organization of the microtubular (MT) cytoskeleton, which were visualized with a refined whole mount immunolocalization technology and 3D confocal laser scanning microscopy. A ‘mild’ heat stress induced microspores to elongate, to rearrange their MT cytoskeleton and to re-enter the cell cycle and perform a predictable sequence of divisions. These events led to the formation of a filamentous suspensor-like structure, of which the distal tip cell gave rise to the embryo proper. Cells of the developing pro-embryo characterized endoplasmic (EMTs) and cortical microtubules (CMTs) in various configurations in the successive stages of the cell cycle. However, the most prominent changes in MT configurations and nuclear DNA replication concerned the first sporophytic division occurring within microspores and the apical cell of the pro-embryo. Microspore embryogenesis was preceded by pre-prophase band formation and DNA synthesis. The apical cell of the pro-embryo exhibited a random organization of CMTs and, in relation to this, isotropic expansion occurred, mimicking the development of the apical cell of the zygotic situation. Moreover, the apical cell entered the S phase shortly before it divided transversally at the stage that the suspensor was 3–8 celled

Variability in Expression of Male Fertility in Triticale (Xtriticosecale Wittmack) With Triticum Timopheevi Cytoplasm

We present a reliable, visual method for evaluation of the level of male fertility during flowering, that is indispensable for breeding of hybrid cultivars of winter triticale based on the cms-T.timopheevi system. Detailed observations of anther development were performed on 20 F2 and BC1 plants derived from crosses between male-sterile and fertility restoring lines. Variation of anther development within florets, spikelets, spikes, and among spikes of the same plant was examined..

Comparative distribution of markers on consensus reference wheat map and linkage groups from A genome of HM-DH population.

<p>Comparative distribution of markers on consensus reference wheat map and linkage groups from A genome of HM-DH population.</p