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KMID : 0368419980410030170
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Journal of Plant Biology
1998 Volume.41 No. 3 p.170 ~ p.177
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Ultrastructural Aspects of Leaves in Festuca ovina and Poa sphondylodes (C-3 Poaceae)
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Kim, In Sun
Pak, Jae Hong/Seo, Bong Bo/Song, Seung Dal
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Abstract
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Structural aspects of the leaves of two common festucoids, Festuca ovina and Poa sphondylodes, have been examined employing the electron microscopy . The nature of vascular bundles and of sheaths that surround vascular tissues was discussed in the study. The festucoids exhibited a non-Kranz C-3 anatomy with more than four mesophyII cells separating the bundle sheaths of a leaf blade. Vascular tissues in these Festuca and Poa leaves were surrounded by a double sheath: an inner distinct mestome sheath (MST) and an outer indistinctive layer of parenchymatous bundle sheath (PBS) cells. The PBS cells were much larger than the MST and had thin walls. The MST cells were relatively small and rectangular in P. sphondylodes and more or less hexangular in transverse sections of F. ovina. In P. sphondylodes, MST had conspicuously thickened inner tangential walls with asymmetrically uninterrupted suberized lamellae in radial and tangential walls. In most differentiated MST cells, all walls were highly suberized. During suberin deposition, MST cells were quite vacuolated and most of the cytoplasm was present as a thin peripheral layer. However, MST walls in F. ovina revealed very thin suberized lamellae with translucent striations. No chloroplasts were detected in P. sphondylodes, whereas the MST in F. ovina contained small chloroplasts. Plasmodesmata were well developed in the primary pit fields of walls between MST and vascular cells, and between adjacent MST cells. Plasmodesmata were less frequent in the walls between the inner and outer sheath cells. Suberized lamellae were totally absent from the PBS cell walls in all veins. External to the PBS, the mesophyII comprised thin walled cells with abundant intercellular spaces. Peripherally arranged chloroplasts in the mesophyII were numerous and often larger than those of PBS and MST cells. Characteristics associated with C-3 and other ultrastructural features were also discussed in the study.
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