Bakos Ferenc, Szabó László, Olmedilla Adela, Barnabás Beáta
Plant Cell Biology Department, Agricultural Research Institute, Hungarian Academy of Sciences, Martonvásár, Hungary.
Sex Plant Reprod. 2009 Mar;22(1):15-25. doi: 10.1007/s00497-008-0087-7. Epub 2008 Oct 11.
There is currently great interest shown in understanding the process of embryogenesis and, due to the relative inaccessibility of these structures in planta, extended studies are carried out in various in vitro systems. The culture of isolated zygotes in particular provides an excellent platform to study the process of in planta embryogenesis. However, very few comparisons have been made between zygotic embryos grown entirely in cultures and those grown in vivo. The present study analyses the differences and similarities between the in vitro and in vivo development of wheat zygotic embryos at the level of morphology and histology. The study was possible thanks to an efficient culture system and an appropriate method of preparing isolated wheat zygotes for microscopy. The in vitro embryos were fixed, embedded and sectioned in the two-celled, globular, club-shaped and fully differentiated stages. Embryos developing in vitro closely followed the morphology of their in planta counterparts and their cell types and tissues were also similar, demonstrating the applicability of the present culture system for studying the process of zygotic embryogenesis. However, some important differences were also detected in the case of in vitro development: the disturbance of or lack of initial polarity led to changes in the division symmetry of the zygotes and subsequently to the formation of uniform cells in the globular structures. Presumably, differences between the in vitro and in planta environments resulted in a lower level of differentiation and maturation in in vitro embryos and in abundant starch and protein accumulation in the scutellum.
目前，人们对了解胚胎发生过程表现出极大的兴趣，由于这些结构在植物体内相对难以获取，因此在各种体外系统中进行了深入研究。特别是分离合子的培养为研究植物体内胚胎发生过程提供了一个极好的平台。然而，在完全在培养物中生长的合子胚与在体内生长的合子胚之间进行的比较非常少。本研究从形态学和组织学水平分析了小麦合子胚体外和体内发育的差异与相似性。由于高效的培养系统和一种合适的制备用于显微镜观察的分离小麦合子的方法，该研究得以进行。体外胚胎在二细胞期、球形期、棒状期和完全分化期进行固定、包埋和切片。体外发育的胚胎紧密遵循其在植物体内对应物的形态，其细胞类型和组织也相似，这证明了本培养系统在研究合子胚胎发生过程中的适用性。然而，在体外发育的情况下也检测到了一些重要差异：初始极性的紊乱或缺乏导致合子分裂对称性的改变，随后在球形结构中形成均匀的细胞。据推测，体外和植物体内环境之间的差异导致体外胚胎的分化和成熟水平较低，以及盾片中淀粉和蛋白质的大量积累。
