2024年2月22日 星期四
睡莲生殖器官发育过程中解剖结构的变化
Changes of anatomical structure during the development processes of reproductive organs of Nymphaea tetragona
2022年 第31卷 第1期 页码[21-28]    下载全文[22.4MB]  
摘要


为了解睡莲(Nymphaea tetragona Georgi)生殖器官的发育过程,采用石蜡切片技术对睡莲的小孢子和雄配子体横切面以及大孢子、雌配子体和子房纵切面的解剖结构变化进行观察,并采用离体培养和人工授粉等技术研究花粉特征、花粉萌发率以及自交结实率。结果表明:睡莲的雄配子体总体上经历了花粉母细胞期、减数分裂期、四分体期、小孢子游离期、单核靠边期、单核花粉期、双核花粉期一系列过程,最终发育成成熟花药;其花药包含4个花粉囊,花药壁由外向内依次由1层表皮细胞、1层药室内壁细胞、2层中层细胞和1层分泌型绒毡层细胞组成;成熟花粉粒呈球状至椭球状,花粉沟为环型萌发沟;离体花粉萌发率为45.2%。睡莲的雌配子体总体上经历了大孢子母细胞期、二分体期、四分体期、单核胚囊期、双核胚囊期、四核胚囊期一系列过程,最终发育成完整的胚囊;大孢子四分体中靠近合点区的大孢子为功能大孢子;其成熟胚囊为4细胞4核型胚囊,由1个单核中央细胞、1个卵细胞和2个助细胞组成;其胚珠为双珠被、厚珠心和边缘胎座。睡莲的胚胎发育经历了球形胚、椭球形胚和菱形胚3个阶段,其胚乳为细胞型胚乳。此外,睡莲生殖器官发育过程中会出现一些发育异常的现象,其中,雄配子体的发育可出现绒毡层细胞提前解体和四分体形状不规则等现象,导致花粉发育异常;雌配子体的发育过程中可出现大孢子发育停滞和胚囊内细胞核异常解体等现象;人工授粉后子房内可出现胚胎停止发育且结构混乱和细胞核解体等异常现象,导致胚胎败育。研究结果表明:睡莲功能大孢子位于合点区和4细胞4核成熟胚囊是区别于大多数被子植物的重要生殖特征;大、小孢子,雌、雄配子体和胚胎发育过程中的败育可能会降低睡莲的异花自交结实率。

Abstract

In order to understand the development processes of reproductive organs of Nymphaea tetragona Georgi, the changes of anatomical structure of microspore and male gametophyte transverse sections and megaspore, female gametophyte and ovary longitudinal sections were observed by using the technology of paraffin section, and the pollen characteristics, pollen germination rate, and self-seeds setting rate were studied by using technologies such as in vitro culture and artificial pollination. The results show that the male gametophyte of N. tetragona develops into mature anther through a series of processes, namely pollen mother cell stage, meiosis stage, tetrad stage, microspore free stage, mononuclear sideline stage, mononuclear pollen stage, and binuclear pollen stage; the anther contains four pollen sacs, and the anther wall is composed of one layer of epidermal cells, one layer of anther chamber wall cells, two layers of middle layer cells, and one layer of secretory tapetum cells from outside to inside; the shape of mature pollen grain is spherical to ellipsoid, and the pollen groove is a ring germination groove; the germination rate of pollen in vitro is 45.2%. The female gametophyte of N. tetragona develops into a complete embryo sac through a series of processes, namely megaspore mother cell stage, dyad stage, tetrad stage, mononuclear embryo sac stage, binuclear embryo sac stage, and tetranuclear embryo sac stage; and the megaspore near the chalazal region of megaspore tetrad is functional megaspore; the mature embryo sac is a four-cell/four-nuclear embryo sac, which is composed of one mononuclear central cell, one egg cell, and two synergids; the ovule is double integuments, thick nucellus and marginal placentation. The embryonic development of N. tetragona goes through three stages, namely globular embryo, ellipsoidal embryo, and rhombic embryo, and its endosperm is cellular endosperm. In addition, some developmental abnormalities can occur in the development processes of reproductive organs of N. tetragona, in which, there are phenomena such as early disintegration of tapetum cells and irregular shape of tetrad during the development of male gametophyte, resulting in abnormal pollen development; and there are megaspore stagnation and abnormal nuclear disintegration in embryo sac during the development of female gametophyte; in the ovary after aritificial pollination, there are abnormal phenomena such as embryo stop development, structural disorder, and nuclear disintegration, resulting in embryo abortion. It is suggested that the functional megaspores of N. tetragona located at the chalazal region and four-cell/four-nuclear mature embryo sacs are important reproductive characteristics different from most angiosperms; the abortions during megaspore, microspore, male and female gametophyte, and embryo development may reduce the crossselfseeds setting rate of N. tetragona.

 

关键词睡莲; 生殖器官; 解剖结构; 雌配子体; 雄配子体; 胚胎发育
Key wordsNymphaea tetragona Georgi; reproductive organ; anatomical structure; female gametophyte; male gametophyte; embryo development
作者孙春青1,2, 陶美奇1, 姚悦梅1, 戴忠良1
所在单位1. 江苏丘陵地区镇江农业科学研究所, 江苏 句容 212400; 2. 南京农业大学园艺学院, 江苏 南京 210095
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基金项目国家自然科学基金资助项目(31701948); 镇江市重点研发计划项目(NY2021016)