摘要
【目的】通过对水松生殖发育解剖结构的研究，探讨水松属分类地位，分析水松种子严重败育的原因，进一步为水松繁殖和保护提供丰富、完善的胚胎学研究资料。【方法】2011年9月至2013年9月，采用石蜡切片技术对水松大孢子发生、雌配子体发育和胚形成过程进行系统地显微观察，详细观测水松雌球果发育过程中外部形态变化。【结果】9—11月为水松雌球果芽分化期，12月至翌年5月为大孢子发生和雌配子体发育期，6月为受精期，6月下旬至7月为原胚发育期，8月为早期胚发育期，9月为后期胚发育期。大孢子母细胞减数分裂形成直线型四分体，其中3个大孢子逐渐退化，仅靠近合点端的大孢子发育成为功能大孢子；复合颈卵器由6～17个颈卵器构成，外层有双核套层细胞。套层细胞具有明显的极性分布；复合颈卵器大多数着生于雌配子体顶端，少数侧生；中央细胞不形成卵核和腹沟细胞，直接发育为成熟的卵细胞；精细胞进入颈卵器时，不损伤颈细胞；受精作用主要发生在颈卵器中部，偶尔发生在颈卵器两端。精核与卵核融合过程中，精核的核仁发生解聚和复聚；合子转移到合点端后，进行有丝分裂形成原胚自由核；受精作用属于有丝分裂前配子融合类型。原胚发育属松杉类标准型，为简单多胚类型；原胚发育形成原胚柄，但不形成初生胚柄。受精作用过程中，存在严重授粉不足现象。【结论】基于雌配子游离核、颈卵器和颈细胞数目，颈卵器类型和着生位置，中央细胞及原胚发育等特征综合分析表明，水松属与台湾杉属、水杉属、柳杉属、落羽杉属亲缘关系密切，与杉木属亲缘关系较近。授粉不足可能是水松大量瘪粒种子形成的主要原因。
Objective]This study aims to get insight of the systematic position of Glyptostrobus pensilis and to explore developmental abnormalities of seeds of this species based on its reproductive developmental anatomy. Further to enrich and complement the current understanding of G. pensilis in reproductive biology and to provide a theoretical basis for designing conservation strategies for this species.[Method]During the period of three years from September,2011 to September,2013,we observed morphological changes from cone buds emergence to seed cones formation and internal changes during megasporogenesis,gametophyte development,and embryogenesis using paraffin-embedded-sectioning and hematoxylin-staining. [Result]From September to November,the bud scales differentiated into young ovulate cones,and ovulate cones developed from December to May of following year. Fertilization took place in June. The proembryony development was from late June to July; early embryo development was during August; mature embryo development was during September. The meiotic division of the megasporocyte produced four megaspores in a linear tetrad formation. The three megaspores near the micropyle disintegrated,while the megaspore near the chalaza developed into a functional megaspore. The archegonia complex consisting of 6 to 17 archegonia covered by a layer of jacket cells with two nucleuses, were positioned terminally or few laterally. The layer of jacket cells had obvious polarity distribution. The central cell did not divide to form the egg nucleus and ventral canal nucleus. Instead,the central cell directly developed into a mature egg cell. The sperm cell enters archegonium without damage to the neck cells. The fertilization mainly occurred in the center, and occasionally upper or lower part of the archegonium. During the sperm-egg fusion process,the nucleolus of sperm nucleus broken down and gradually disappeared,then become apparent after fused with the egg nucleus. The zygote gradually moved to the bottom of the archegonia,and undergoing mitosis to form proembryony free nuclei. The fertilization is the type of pre-mitotic syngamy. The proembryony belongs to the standard type of coniferales, and has simple polyembyrony pattern. The proembryony only developed into the prosuspensor but not formed the primary suspensor. It has been observed that severe insufficient pollination during fertilization.[Conclusion]The gametophyte development and embryogenesis in G. pensilis,such as number of free nuclei of megagametophyte,archegonia and neck cells,the type and position of archegonia,development process of central cell and proembryony,were quite similar to genera Taiwania, Metasequoia, Cryptomeria, Taxodium,reflecting a closer taxonomic relationship to these genera than to genus Cunninghamia. Insufficient pollination might be an important cause for‘empty seeds’in G. pensilis.
出处
《林业科学》
EI
CAS
CSCD
北大核心
2015年第6期50-62,共13页
Scientia Silvae Sinicae
基金
林业公益性行业专项经费项目(201104033)
关键词
大孢子发生
配子体发育
胚发生
水松
megasporogenesis
gametophyte development
embryogenesis
Glyptostrobus pensilis
