摘要
【目的】植物胚胎形成及发育过程与其种子的饱满程度、发芽率息息相关,旨在从胚胎学方面解释圆齿野鸦椿空籽率高、种子发芽率低的原因。【方法】于2015年5月起,在该树种接近开花时每天观察一次;开花期间,每隔几个小时观察一次,采集不同发育阶段的花芽,将其外部鳞片剥离后处理成小份,放入含70%FAA固定液中抽真空保存。采用常规石蜡制片技术,电子显微镜下拍照,观察该树种大、小孢子发生和雌、雄配子体形成过程。于开花期,将当天开放的新鲜花朵及其花药用双面胶处理后喷金,电子显微镜下观察花粉形态,并进行拍照。【结果】圆齿野鸦椿雄蕊多为5枚,每枚含4个小孢子囊。花药壁由绒毡层、中层、药室内壁和表皮组成;在花药发育过程中,药室内壁逐渐增厚,中层逐渐吸收解体,绒毡层亦分解,为小孢子发育提供营养。小孢子四分体时期为四面体型,后发育为雄配子体;成熟花粉椭圆形,花粉粒2-细胞型。花药、花粉粒均为金黄色,花粉粒赤道面观呈长球形,具3条萌发沟,极面观呈3裂圆形,属N3P4C5类型花粉。上位子房,3室,每室横生胚珠3-4枚,中轴胎座;四分体时期子细胞多为线性排列,少为“田”字形排列,后发育为雌配子体;蓼型胚囊,七胞八核。圆齿野鸦椿雌雄配子体形成过程中,存在空腔花粉粒以及绒毡层降解异常,功能大孢子退化以及不能正常有丝分裂形成八核胚囊的现象,从而出现花粉和胚囊败育以及落花落果。【结论】胚胎发育异常是造成该树种空籽率高、种子发芽率低的主要原因之一。
[Objective]The formation and development of plant embryos are closely related to the fullness and germination rate of seeds.The aim of this study is to explain the reasons for the high empty seed rate and low seed germination rate of Euscaphis konishii in the aspect of embryology.[Method]Since May 2015,Eusca⁃phis konishii was observed once a day when it was close to flowering;during the flowering period,it was observed every few hours.The flower buds in different stages of development were collected,and the outer scales were peeled off and processed into small aliquots which were put into 70%FAA fixative and vacuumed for storage.The megasporogenesis,microsporogenesis and formation of female and male gametophytes of Euscaphis kon⁃ishii were observed by using paraffin wax,and photographed under an electron microscope.During the flowering period,the fresh flowers and their anthers that opened that day were treated with double-sided tape and sprayed with gold,and the pollen morphology was observed under an electron microscope and photographed.[Result]The results show that most of the stamens of Euscaphis konishii were 5,each containing 4 microsporangia.The anther wall was composed of tapetum,middle layer,endothecium and epidermis.During the development of anthers,the endothecium gradually thickened,the middle layer was gradually absorbed and disintegrated,and the tapetum was also decomposed to provide nutrients for the development of microspores.The microspores were arranged in tetrahedron in the tetrad stage which later developed into male gametophytes.Mature pollen was oval and it was of 2-cell type.Both anthers and pollen grains were golden yellow.Pollen grains were oblong in equatorial view and they had three germination grooves.Pollen grains were 3-lobed round in polar view.The pollen of Euscaphis konishii belonged to N3P4C5 type pollen.The upper ovary was 3 compartments,with 3-4 transverse ovules per compartment.It belonged to axial placenta.In the tetrad period,the cells were arranged linearly mostly and were rarely arranged in the shape of“田”which later developed into female gametophytes.It was polygonum type embryo sacs and contained seven cells and eight nuclei.During the formation of male and female gametophytes of Euscaphis konishii,there were hollow pollen grains and abnormal tapetum degradation,functional megaspores degenerated and failed to mitose into eight-nucleated embryo sacs,which resulted in pollen and embryo sac abortion and fruit drop.[Conclusion]Abnormal embryonic development is one of the main reasons for the high empty seed rate and low seed germination rate of Euscaphis konishii.
作者
万瑞琪
邵晓雪
吴凌敏
涂淑萍
WAN Ruiqi;SHAO Xiaoxue;WU Lingmin;TU Shuping(Jiangxi Agricultural University College of Landscape and Art,Nanchang 330045,China;Jingdezhen City,Jiangxi Province Forestry Institute,Jingdezhen,Jiangxi 333000,China;Jingdezhen City,Jiangxi Province Tobacco Monopoly Bureau,Jingdezhen,Jiangxi 333000,China)
出处
《江西农业大学学报》
CAS
CSCD
北大核心
2021年第4期766-773,共8页
Acta Agriculturae Universitatis Jiangxiensis
基金
江西省重点研发计划项目(20161BBF60068)
江西省林业厅科技创新专项(201812)。
关键词
大孢子发生
小孢子发生
雌、雄配子体形成
圆齿野鸦椿
败育
megasporogenesis
microsporogenesis
formation of female and male gametophytes
Euscaphis konishii
abortion
