甜荞pin型花与thrum型花雌雄蕊发育的比较研究

Development of stamens and carpels on pin typeand thrum type flowers of common buckwheat

关键词:  甜荞, pin型花, thrum型花, 大、小孢子发生, 雌、雄配子体发育

Key words:   Fagopyrum esculentum, pin type flower, thrum type flower, megasporogenesis and microsporogenesis, female and male gametophytes

摘要:

为从形态上研究甜荞(Fagopyrum esculentum)二型花发育的差异性，该文运用石蜡切片技术对甜荞pin型花和thrum型花大、小孢子发生和雌、雄配子体的发育过程进行观察比较。 结果表明:(1)甜荞2种花的 雌蕊、雄蕊发育的细胞学特征有很高的相似性，具直生胚珠、双珠被、厚珠心；大孢子四分体直线型排列，合点 端为功能大孢子，蓼型胚囊。 花药４室，花粉囊壁由表皮、药室内壁、一层中层和一层绒毡层组成，其中绒毡层 发育为腺质型，小孢子母细胞减数分裂过程中的胞质分裂为同时型，小孢子四分体常为四面体型，但thrum型 花花粉囊中偶见十字交叉型小孢子四分体；成熟花粉粒多数为2细胞型，少数为3细胞型。 (2)从2种花雌 蕊、雄蕊的发育进度来看，与pin型花相比，thrum型花小孢子发育相对较慢，雄配子体发育较快，但开花时，两 者雌蕊、雄蕊均发育成熟。 (3)综合甜荞两种花生殖发育的过程来看，其有许多相对原始的胚胎学特征，但也 出现一些如直生胚珠、3细胞型花粉等相对进化的性状。 该研究完善了甜荞二型花生殖发育的形态细胞学资 料的同时，也为理解石竹目物种间的亲缘关系提供了胚胎学证据。

Abstract:

In order to reveal the morphological differences between pin type and thrum type flowers development of common buckwheat. The megasporogenesis, microsporogenesis and development of female and male gametophytes in pin type and thrum type flowers of Fagopyrum esculentum were investigated by using the paraffin section method. The results were as follows:(1)The cytological characteristics of pistil and stamen development of pin type and thrum type flowers had highly similar. Both type flowers had orthotropous ovule, inner and outer integument, and thickly nucellus. Moreover, the megaspore mother cells underwent meiosis and divided into linear type tetrads, and the one in the chalazal end was functional, which suggested that their development of embryo sac belonged to Polygonum type. The anther had four chambers and the anther wall was composed of epidermis, endothecium, one layer of middle layer and glandular tapetum. In addition, meiosis of microspore mother cell was followed by simultaneous cytokinesis and results in common tetrahedral tetrads. Furthermore, most of tetrads were tetrahedral, but a small number of decussate tetrads were also observed in thrum flower. Most of mature pollen grains were 2-cell type, and 3-cell type pollen grains were also observed in pin type and thrum type flowers.(2)Comparing the pistil and stamen developmental progress between the pin type and thrum type flowers, the development of microspores in thrum type flower was more slowly than that of the pin type flower, but the male gametophytes in thrum type flower grew faster. However, mature embryo sac and pollen grains were observed when pin type and thrum type flowers bloomed.(3)According to the reproduction development process of two type flowers, many relatively primitive embryological characteristics, and some relatively evolutionary embryological characteristics, such as orthotropous ovule and 3-cell type pollen grains, coexisted in common buckwheat. This study not only accumulated the morphological data of the distylous flower reproductive development in common buckwheat, but also provided embryological evidence for understanding the genetic relationships among the species of Caryophyllales.