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首页> 外文期刊>International journal of plant sciences >SPORE WALL ULTRASTRUCTURE IN THE TOURNAISIAN LYCOPSID OXROADIA GRACILIS
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SPORE WALL ULTRASTRUCTURE IN THE TOURNAISIAN LYCOPSID OXROADIA GRACILIS

机译：土瓜类莱比锡草叶甲的孢子壁超微结构

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Premise of research. The pseudoherbaceous Mississippian lycopsid Oxroadia gracilis has been placed phylo-genetically between the herbaceous protolepidodendraleans (e.g., Leclercqia) and the arborescent lepidodendrids of the Pennsylvanian. The presence or absence of a particular ultrastructural feature in the microspores could support or complicate this interpretation. This feature, which manifests as a multilamellated zone (MZ) in the spore wall between the proximal trilete arms, was thought to be characteristic of the microspores of heterosporous lycopsids until it was demonstrated to be present in the homosporous taxon Leclercqia. It has not, however, been seen in the microspores of arborescent lepidodendrids. If Oxroadia spores possess this feature, the genus may be more closely related to a lineage that leads to extant Isoetes and Selaginella, both of whose microspores also possess this feature. If this feature is lacking in Oxroadia, this may suggest a closer relationship to the lepidodendrids. Methodology. This feature can only be confirmed by examination with transmission electron microscopy. Pivotal results. Microspores of Oxroadia do possess a MZ, adding weight to the proposal that it is allied with a lineage leading to extant heterosporous lycopsids. Furthermore, both the microspores and the megaspores have comparable structures in the innermost spore wall. This is only the second plant in which both microspores and megaspores have been shown to have MZs, and it is the oldest. Conclusions. These results may support the placement of Oxroadia as part of a lineage between the Devonian genus Leclercqia and the extant heterosporous lycopsids. Alternatively, the MZs may have yet to be discovered in microspores of lepidodendrids, and they may be present throughout the lycopsids.
机译：研究前提。拟皮脂性的密西西比州番茄红单胞菌（Oxroadia gracilis）已在系统发育上位于草本的原鳞翅类植物（例如Leclercqia）和宾夕法尼亚州的树状鳞翅类之间。小孢子中是否存在特定的超微结构特征可能支持或使这种解释复杂化。该特征在近端的三臂臂之间的孢子壁上表现为一个多层区域（MZ），被认为是异孔番茄红素微孢子的特征，直到它被证明存在于同孔类群Leclercqia中。然而，在树状鳞茎类的小孢子中尚未发现它。如果Oxroadia孢子具有此特征，则该属可能与导致现存的Isoetes和Selaginella的谱系更紧密相关，它们的小孢子也都具有此特征。如果Oxroadia中缺少此功能，则可能表明它与鳞翅目动物有更紧密的关系。方法。此功能只能通过透射电子显微镜检查来确认。关键的结果。 Oxroadia的小孢子确实具有MZ，这增加了它与导致现存的异孔番茄红素的血统相关的提议的分量。此外，小孢子和大孢子在最内层的孢子壁上都具有可比的结构。这仅是第二种同时显示小孢子和大孢子都具有MZ的植物，并且是最古老的植物。结论。这些结果可能支持Oxroadia作为泥盆纪属Leclercqia和现存的异孔番茄红素之间的血统的一部分。或者，可能尚未在鳞翅目的小孢子中发现MZ，并且它们可能存在于整个番茄红素中。

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