Comparative ultrastructure of plasmodesmata of Chara and selected bryophytes: Toward an elucidation of the evolutionary origin of plant plasmodesmata
Comparative ultrastructure of plasmodesmata of Chara and selected bryophytes: Toward an elucidation of the evolutionary origin of plant plasmodesmata
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DOI：
10.2307/2446040
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发表时间：
1997-09-01
影响因子：
3
通讯作者：
Lavin, CA
中科院分区：
文献类型：
--
作者：
Cook, ME;Graham, LE;Lavin, CA
我们已经使用透射电子显微镜检查的charophycean绿色轮藻zeylanica的胞间连丝，和puperous早期分歧bratites Monoclea gottschei（苔），Notothylas orbicularis（金鱼藻），和泥炭藓fimbriatum（苔藓），试图了解种子植物胞间连丝可能起源。检查的三个brabrites有桥小管。此外，单壳藻的胞间连丝具有分枝状，泥炭藓的胞间连丝在颈部周围具有密集的染色区域，并具有环状的壁特化。在轮藻，纵向切片显示内质网（ER），有时似乎与胞间连丝，但这是罕见的，尽管丰富的ER在细胞周边。在所有三种固定方法中，横截面视图显示内部中心结构，在某些情况下，该结构似乎通过辐条状结构与质膜连接。胞间连丝甚至存在于形成细胞板的不完全形成的网状结构中，由此我们得出结论，初级胞间连丝在锡兰轮藻的胞质分裂中形成。基于这些结果，看来，轮藻的胞间连丝可能比种子植物的胞间连丝特化程度低，并且复杂的胞间连丝可能在现存的bratites谱系分化之前在陆地植物的祖先中进化。
We have used transmission electron microscopy to examine plasmodesmata of the charophycean green alga Chara zeylanica, and of the putatively early divergent bryophytes Monoclea gottschei (liverwort), Notothylas orbicularis (hornwort), and Sphagnum fimbriatum (moss), in an attempt to learn when seed plant plasmodesmata may have originated. The three bryophytes examined have desmotubules. In addition, Monoclea was found to have branched plasmodesmata, and plasmodesmata of Sphagnum displayed densely staining regions around the neck region, as well as ring-like wall specializations. In Chara, longitudinal sections revealed endoplasmic reticulum (ER) that sometimes appeared to be associated with plasmodesmata, but this was rare, despite abundant ER at the cell periphery. Across all three fixation methods, cross-sectional views showed an internal central structure, which in some cases appeared to be connected to the plasma membrane via spoke-like structures. Plasmodesmata were present even in the incompletely formed reticulum of forming cell plates, from which we conclude that primary plasmodesmata are formed at cytokinesis in Chara zeylanica. Based on these results it appears that plasmodesmata of Chara may be less specialized than those of seed plants, and that complex plasmodesmata probably evolved in the ancestor of land plants before extant lineages of bryophytes diverged.