雄性不育与可育楸树花发育的细胞学比较研究

Development of Male and Female Gametophytes between Fertile Line and Male Sterile Line's Flowers of Catalpa bungei C. A. Meyer.

楸树(Catalpa bungei C.A.Meyer.)属紫葳科(Bignoniaceae)梓树属(Catalpa),落叶乔木,是我国特有的珍贵优质用材树种。本文用石蜡切片法对可育株和雄性不育株楸树的大、小孢子发生及雌、雄配子体发育过程进行了详细地比较观察。结果表明:可育株和不育株楸树雌蕊的发育基本相同,胚珠倒生,薄珠心,单珠被,胚囊发育为蓼型。可育株雄蕊花药四室,药隔薄壁组织发达;异型绒粘层,由药壁绒粘层和药隔绒粘层组成;花药壁表皮细胞在小孢子母细胞减数分裂前后开始径向伸长加厚,直到花药开裂并不降解,这可能与花药开裂有关;成熟花粉为四合花粉。雄性不育株花药的早期发育到次生造胞细胞时期与可育雄蕊的相同,小孢子母细胞减数分裂前绒毡层发育不充分;四分体时期,绒毡层细胞高度液泡化,细胞质稀薄,已提前降解,小孢子四分体因绒毡层结构和功能异常而不能正常发育,因此楸树雄性不育为结构型雄性不育。

Catalpa bungei C. A. Meyer, a deciduous tree belonged to Catalpa Bignoniaceae, is a unique timer tree species with high quality and value in China. Paraffin sectioning with optical microscopy was conducted to investigate the development of megasporogenesis, microsporogenesis and the developing process of female and male gametophytes in fertile and sterile lines of C. bungei flowers. The development of pistil in fertile plants and sterile plants were basically the same, including anatropous ovule with simple integument and tenuinucellus, and polygonum type embryo sac. The anther of fertile plants was tetrasporangiate and anther connective parenchyma was well-developed. The heterotype tapetum consisted of anther wall tapetum and anther connective tapetum. Before the meiosis of microspore mother cell, the epidermal cells of anther wal began to elongate and thicken radially without degradation till anther cracking, which might be related to anther cracking. The matured pollen of fertile plants were tetrasomic. The anther development of sterile plants in early secondary sporogeous cells stage was almost the same with fertile stamen. The tapetum developed incompletely during the meiosis period of microspore mother cells. The tapetum cells were highly vacuolated with thin cytoplasm and prematurely degraded during the tetrad stage, and the tetrad microspore developed abnormally due to structural and functional abnormity of tapetum. Therefore, the male sterility of C. bungei was structural type male sterility.