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| 越南篦齿苏铁小孢子发生及其系统学意义 | |
| 引用本文： | 欧阳海波,李勇,张寿洲,李楠,吴鸿.越南篦齿苏铁小孢子发生及其系统学意义[J].植物分类学报,2004,42(6):500-512. |
| 作者姓名： | 欧阳海波 李勇 张寿洲 李楠 吴鸿 |
| 作者单位： | 1. 华南农业大学生命科学学院,广州,510642;深圳市仙湖植物园,深圳,518004 2. 深圳市仙湖植物园,深圳,518004 3. 华南农业大学生命科学学院,广州,510642 |
| 摘 要： | 运用常规石蜡切片方法，结合显微荧光技术对越南篦齿苏铁Cycas elongata 小孢子发生和花粉个体发育进行了研究。结果表明：其小孢子叶球5月中下旬开始萌动，小孢子囊着生在小孢子叶远轴面，且3-5小孢子囊以辐射状排列方式聚生成聚合囊。小孢子囊壁由6-7层细胞组成，包括表皮、中层及绒毡层。绒毡层来源于成熟造孢组织的外围细胞，其退化形式为分泌型。6月中旬，小孢子母细胞进入减数分裂I，至6月下旬形成四分体。母细胞减数分裂后胞质分裂的方式与其他苏铁类植物不同，具有连续型与同时型两种类型。7月中旬，小孢子经过2次有丝分裂后，形成3细胞的成熟花粉粒。7月下旬进入散粉状态。在花粉发育过程中，母细胞内淀粉粒的积累及其壁上胼胝质的沉积均呈现规律性变化。 |
| 关 键 词： | 越南篦齿苏铁 小孢子发生 花粉个体发育 |
| 修稿时间： | 2004年5月17日 |
Microsporogenesis of Cycas elongata and its systematic implication |
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| OUYANG Hai-Bo,LI Yong,ZHANG Shou-Zhou,LI Nan,WU Hong.Microsporogenesis of Cycas elongata and its systematic implication[J].Acta Phytotaxonomica Sinica,2004,42(6):500-512. | |
| Authors: | OUYANG Hai-Bo LI Yong ZHANG Shou-Zhou LI Nan WU Hong |
| Affiliation: | OUYANG Hai-Bo 2LI Yong 2ZHANG Shou-Zhou 2LI Nan 1WU Hong 1 |
| Abstract: | Microsporogenesis and pollen ontogeny in Cycas elongata (Leandri) D. Y. Wang were studied to amass additional information on the reproductive biology of cycads and to provide some data for further studies on the factors causing the endangerment of this species. This species tends to initiate the male cones in middle or late May. The microsporophylls bear their microsporangia on the abaxial surface, and 3-5 microsporangia seem to be arranged radially into a sorus with a stalk. The microsporangium wall comprises one epidermis, four to five middle layers, and a tapetum. The tapetum may be derived from the outer layer of mature sporogenous tissue and conforms to secretory type. In the middle of June the microspore mother cells are produced and immediately enter into meiosis. The cytokinesis in the later stage of meiosis is both simultaneous and successive, a phenomenon observed even in the same microsporophyll. Following meiosis, the nuclei of microspore mother cells divide into four to form tetrahedral, isobilateral, tetragonal and occasionally linear tetrads in late June. Subsequently the microspores are released from tetrads. With the development of pollen, the microspores then undergo two asymmetric mitosis to form mature pollen consisting of three cells, i.e., a tube cell, a generative cell and a prothallial cell. Pollen further develops and is dispersed through the dehiscence of the sporangium in late July. In addition, both starch grains and callose have a regular dynamic distribution during the course of microsporogenesis and pollen ontogeny. The phenomenon that the cytokinesis at the later stage of meiosis in microsporogenesis is both simultaneous and successive has not been previously reported in any other cycads, even in other gymnosperms, and thus may have systematic significance and developmental implications. |
| Keywords: | Cycas elongata microsporogenesis pollen ontogeny callose starch grain |
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