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  • 學位論文

台灣肖楠小孢子發育和花粉發育之研究

The Study of Microsporogenesis and Pollen Development in Calocedrus macrolepis Kurz var. formosana (Florin) W. C. Cheng & L. K. Fu

指導教授 : 陳淑華

摘要


台灣肖楠 (Calocedrus macrolepis Kurz var. formosana (Florin) W. C. Cheng & L. K. Fu) 為台灣特有變種之松柏類植物,本研究使用光學顯微鏡、共軛焦顯微鏡、掃描式電子顯微鏡和穿透式電子顯微鏡觀察台灣肖楠小孢子形成和花粉發育的過程,並配合組織化學染色,期望此完整的過程,能提供前驅資料,以利其他台灣肖楠之相關研究。 台灣肖楠為多年生之高大喬木,鱗片狀葉為十字對生,雄毬花的小孢子葉排列亦為十字對生。雄毬花著生於枝條末端,每個雄毬花約由16片小孢子葉聚生而成,每片小孢子葉背軸面下緣有3-6個小孢子囊懸掛。每年八月底雄毬花的花芽開始分化,雄毬花形成。 在孢原組織時期,小孢子囊壁由外而內分別為表皮層、中介層與營養層。小孢子母細胞在十二月底完成減數分裂,立即進行同時型的細胞質分裂,當減數分裂完成,各種形狀的四分體被包於胼胝質壁內,包括長菱形、四面體形和四角形的四分體,營養層細胞壁此時開始分解。胼胝質壁瓦解後,四個單套的小孢子被釋放至小孢子囊腔中,進入自由小孢子時期,此時,漸漸的澱粉粒開始在小孢子細胞質中累積,營養層慢慢與小孢子囊壁脫離,散入至小孢子囊腔中。隨後,花粉外壁外層、外壁內層及內壁開始相繼堆積。接著,小孢子漸漸地液胞化,此時中介層消失,小孢子囊壁只剩下單層的表皮細胞。最後,小孢子進行一次細胞不等的有絲分裂,形成一個大的營養細胞和一個小的生殖細胞,表皮層此時同時兼任花藥內壁的功能,輻射狀加厚以利小孢子囊壁脫水裂開,二月底,成熟花粉粒隨風飄散。 成熟花粉粒具單孔,外壁外層未完整包覆住花粉,其上並黏附有很多烏氏體,花粉粒細胞質內的儲存物質以多醣類為主。花粉粒水分含量僅38.5%,細胞質濃縮呈星狀,且聚集在細胞中央,在FCR檢測下,此成熟的花粉粒幾乎不具活性。在離體實驗中,花粉粒經水合1hr後,細胞質膨脹呈圓形,並在花粉外壁的限制下,擠壓花粉內壁;當花粉內壁被壓縮至極大值時,向外擴張的彈力將外壁繃裂脫離,此時細胞質呈蛋型,花粉內壁體積大幅膨脹;經過24hr的水合反應後,約有70%的花粉粒具有FCR正反應。最後,花粉內壁和細胞質因為水分滲透壓的關係,彼此分離。 由此台灣肖楠小孢子和花粉粒的詳細發育過程,可知其花粉粒在成熟飛散後具有正常活性,能繼續完成授粉和授精的使命。

並列摘要


Calocedrus macrolepis Kurz var. formosana (Florin) W. C. Cheng & L. K. Fu is an endemic conifer in Taiwan. Its wood is precious and valuable. The low seed setting ratio resulted the underproduction of seeds of this plant. Therefore, the development of reproductive organs, especially the male cones, was worth to study. This purpose was investigated by fluorescent microscopy, confocal laser scanning microscopy, light microscopy, scanning and transmission electron microscopy, histochemical analysis, and FCR test, respectively. Leaves of this plant are decussated and scale-like with decurrent base. Three to six microsporangia at abaxial side of microsporophyll arranged decussately as phyllotaxy. Buds of male cones located at the end of the branches initiated differentiation at end-August. At microsporogenous tissue stage, the microsporangium wall could be recognized as epidermis, middle layer and tapetum from outside to inner. During microsporogenesis, simultaneous cytokinesis occurred immediately after meiosis at the end of December. When cytokinesis completed, multiform tetrads were emerged in a microsporangium, including rhomboidal, tetrahedral, and tetragonal tetrads. Tapetum cell began the process of programmed cell death. Then, callose wall dissolved, and four haploid microspores freed into microsporangial locule. Free microspores which were released by dissolved of callose contented of many starch grains in cytoplasm. Within this stage, tapetum was degenerated totally from microsporangial wall and released into microsporangial locule. Development of ectexine, endexine, and intine of microspores was occured immediately. Then, the microspore became vacuolized gradually and middle layer disappear synchronically. However, only one single epidermis layer remained as microsporangial wall. Finally, microspores passed through an asymmetric cell division. A large vegetative cell and a small generative cell were formed in each pollen grain. Function of epidermis at there was similar with endothicium, which radial thickening for anthesis. A mature pollen grain dispersed at next end-February. Each pollen grain had a single pore and ectexine with many adhered Ubisch bodies, and the ectexine not enclose the whole pollen grain. Cytoplasm of mature pollen grains used polysaccharide to be storage material. The water content of mature pollen grains was low (38.5 %), and the cytoplasm was condensed as star-like shape at the central of pollen grain. The percentage of viability of these fresh and dry pollen grains was as low as zero. After partial rehydration in distal water for 1 hr, the cytoplasm was round up, and the intine was compressed by the expansive cytoplasm. Subsequently, the compressed intine made exine split and peel off abruptly. When the pollen grains were continuously rehydrated in vitro, the cytoplasm became egg-shape and the intine was thickened unlimitedly. After rehydration of pollen grains for 24hrs, the maximal percentage of viability with 70% was calculated. After completed hydration of protoplast, outermost part of intine shed off, too. This detail process of this microsporogenesis in this study may support the preliminary and robust information for either further or future male-sterily study in Calocedrus macrolepis var. formosana.

參考文獻


謝金霖 (2004) 台灣肖楠皮部之化學成分研究。台灣大學化學所博士論文,台北市。
周群、李銘鐘、黃清吟 (2002) 肖楠人工林中小徑木強度性質變異性探討。台灣林業科學17(4): 463-469。
鍾振德、郭幸榮、楊政川 (2001) 重建台灣肖楠營養系種子園以促進開花結實之初期成果 台灣林業科學 16(3): 181-196。
Ho, C.-K., Chang, S.-H., and Tsai, J.-Y. (2000). Investigation of the formation of empty seeds in Keteleeria davidiana (Franchet) Beissner var. formosana Hayata. Taiwan J. Forest Sci. 15, 209-227. (Traditional Chinese with English abstract)
鍾永立、胡大維 (1986) 光期與溫度變化對台灣肖楠種子發芽之效應 林業試驗所研究報告季刊 1(2): 63-67。

被引用紀錄


許佳玫(2008)。台灣穗花杉小孢子形成與花粉發育之研究〔碩士論文,國立臺灣大學〕。華藝線上圖書館。https://doi.org/10.6342%2fNTU.2008.01492

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