College of Horticulture and Plant Protection, Yangzhou University, Yangzhou, Jiangsu, PR China.
Plant Signal Behav. 2012 Dec;7(12):1687-94. doi: 10.4161/psb.22898. Epub 2012 Dec 1.
Metasequoia glyptostroboides, a famous relic species of conifer that survived in China, has been successfully planted in large numbers across the world. However, limited information on male cone development in the species is available. In this study, we observed the morphological and anatomical changes that occur during male cone development in M. glyptostroboides using semi-thin sections and scanning electron microscopy. The male cones were borne oppositely on one-year-old twigs that were mainly located around the outer and sunlit parts of crown. Male cones were initiated from early September and shed pollen in the following February. Each cone consisted of spirally arranged microsporophylls subtended by decussate sterile scales, and each microsporophyll commonly consisted of three microsporangia and a phylloclade. The microsporangial wall was composed of an epidermis, endothecium, and tapetum. In mid-February, the endothecium and tapetum layers disintegrated, and in the epidermal layer the cell walls were thickened with inner protrusions. Subsequently, dehiscence of the microsporangia occurred through rupturing of the microsporangial wall along the dehiscence line. These results suggest that the structure, morphology, architecture and arrangement of male cones of M. glyptostroboides are mainly associated with the production, protection and dispersal of pollen for optimization of wind pollination.
水杉，一种在中国幸存下来的著名的针叶树活化石，已经成功地在世界各地大量种植。然而，关于该物种雄球花发育的信息有限。在这项研究中，我们使用半薄切片和扫描电子显微镜观察了水杉雄球花发育过程中的形态和解剖变化。雄球花对生在一年生小枝上，主要位于树冠的外部和向阳部位。雄球花于 9 月初开始形成，并在次年 2 月散出花粉。每个球果由螺旋排列的小孢子叶组成，小孢子叶由交叉排列的不育鳞片所覆盖，每个小孢子叶通常由三个小孢子囊和一个营养叶组成。小孢子囊壁由表皮、内皮层和绒毡层组成。2 月中旬，内皮层和绒毡层解体，表皮层的细胞壁增厚并出现内突。随后，小孢子囊沿着开裂线破裂，实现开裂。这些结果表明，水杉雄球果的结构、形态、构造和排列主要与花粉的产生、保护和传播有关，以优化风媒传粉。
