Chinese Bulletin of Botany ›› 2019, Vol. 54 ›› Issue (5): 596-605.DOI: 10.11983/CBB18261

• EXPERIMENTAL COMMUNICATIONS • Previous Articles     Next Articles

Megasporogenesis, Microsporogenesis and Development of Male and Female Gametophytes of Clematis heracleifolia

Yi Yang1,Na Wang1,Kuiling Wang1,Qinghua Liu1,Wei Li1,Xiao Guo1,Yingjie Ma2,Qingchao Liu1,*()   

  1. 1. College of Landscape Architecture and Forestry, Qingdao Agricultural University, Qingdao 266109, China
    2. Weihai Shuimuyuan Design Co. Lid, Weihai 264205, China
  • Received:2018-12-05 Accepted:2019-06-18 Online:2019-09-01 Published:2020-03-10
  • Contact: Qingchao Liu

Abstract: In Clematis (Ranunculaceae) species show significant differences in floral morphology and structures, consistent with their complex genetic background. Thus, it is important to study the embryological characteristics prior to any attempts of breeding by hybridization. Here, we report the characterization of microsporogenesis, microgametogenesis, megasporogenesis and macrogametogenesis of Clematis heracleifolia by floral dissection. We show that C. heracleifolia is androdioecy. Aborted microgametophyte cells are observed in the majority of bisexual flowers but occasionally found in male flowers, which results in the formation of functional female flowers. However, in a small number of normal bisexual flowers, male gametophytes mature faster than that of female gametophytes. During microsporogenesis, the tetrasporangiate anther is formed, followed by simultaneous microsporocyte cytokinesis, and the formation of glandular tapetum, occasionally with amoeboid tapetum. After meiosis, the microspores tetrads are mostly tetrahedral, and occasionally symmetrical. The wall of mature anther contains fibrous thickening epidermis and endothecium. Pollen grains are spheroidal, pantocolpate, and 2-celled. The ovary has one chamber with a normal and a few degraded ovules, which contains a anatropous, unitegmic, tenuinucellate, and Polygonum-type embryo-sac. A linear tetrad of megaspores and dikaryocyte antipodal cells can be observed. This species may belong to a transitional clade within Clematis. In breeding practice for C. heracleifolia, it is advised to use plants bearing male flowers and hermaphrodite flowers as male and female parents, respectivley, with the bisexual flowers of 0.5-0.8-cm-long to be emasculated.

Key words: Clematis heracleifolia, Clematis, gametophyte, Ranunculaceae, sporophyte