Calcium crystal and silicic deposition in some species of terrestrial and epiphytic orchid plants and the distribution and development of raphide crystal idioblasts in the leaves of Anoectochilus formosanus Hay.

• Main Authors: Yi Ru Huang, 黃憶汝
• Other Authors: Ling-Long Kuo-Huang
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/37674570627795330560

碩士 === 國立臺灣大學 === 植物學研究所 === 89 === The morphology and distribution of calcium crystals and silica deposition in the leaves of nine species (seven genera) of terrestrial orchids and thirteen species (ten genera） of epiphytic orchids were investigated. All of the studied orchids contain calcium oxalate crystals in the shape of six-eight sided raphides. Dendrobium aurantiacum, D. falconer, Dendrochilum uncatum, Pomatocalpa acuminata and Calanthe densiflora have druses in the leaf. Pholidota cantonensis has styloids. The results show that there are more types of calcium oxalate crystals in the epiphytic orchids. Nevertheless, the density of raphides in the leaves of the terrestrial orchids is higher than that in the epiphytic orchids.Most of the studied epiphytic orchids have silica body in the bundle sheath cells. However, there is no silica body in the leaves of Bulbophyllum affine, Holcoglossum guasipinifolium, and Pomatocalpa acuminata. Otherwise, the silica body was observed only in the leaves of Bletilla formosana, and not in the other studied terrestrial orchids. Two types of silica bodies were found. In B. formosana, Dendrochilum uncatum, and Oncidium Sweet Sugar the silica bodies are conical in shape, and the others are spherical in shape. Besides, the ultrastructural changes of the leaf development and the formation of the calcium oxalate crystal idioblasts in the mesophyll of Anoectochilus formosanus were studied. Effects of calcium concentrations on the leaf development of A. formosanus were studied by tissue culture processes.The leaf morphogenesis of A. formosanus is as follows: crescent-shaped leaf primordium (＜0.1 mm), hood-shaped leaf primordium (0.1-0.3 mm), straight leaf primordium (0.3-1 mm), rolled-leaf (1-33 mm), and unfolded mature leaf (16-42 mm). Crystal initial idioblasts are found in the apex of 1 mm leaf primodium and large number are detected in the 2-3.5 mm rolled-leaves. The development of the raphide crystal idioblast is divided to six stages: (1) crystal idioblast initiation, (2) crystal chamber formation, (3) crystal growth, (4) ER expanded, (5) mucilage accumulation, and (6) crystal idioblast maturation. There are an enlarged nucleus and nucleoli in crystal idioblast of all stages and numerous spherosomes in initiation stage. The vacuoles contain electron-dense amorphous materials, which are association with the crystals and attached to the tonoplast. The morphology of plastids in some crystal idioblast are different from that in normal cells, and early literatures described that in crystal idioblast as the crystalloplatids One to several lobe regions are formed on the periphery of the crystalloplastids. The crystalloplastids contain insoluble polysaccharides and proteins. After the crystal chamber form in the vacuole, the crystal accumulates in these chambers and mucilage fills in the vacuole. There is high electron-dense mucilage sheath packed the raphide. In the mature raphide crystal cells, there are many lamellae sheath between the crystal. There are no distinct effects on the development of the leaves of A. formosanus cultured with different concentrations of calcium ion in the medium: 1/8 Ca (0.19 mM), 1/4 Ca (0.374 mM), 1 Ca (1.496 mM), 4 Ca (5.586 mM), and 8 Ca (11.972 mM). However, the density of crystals in leaves is increased with increasing concentrations of calcium ion.