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Bulletin of Botanical Research ›› 2020, Vol. 40 ›› Issue (2): 161-171.doi: 10.7525/j.issn.1673-5102.2020.02.001

• Research Report •     Next Articles

Pollinia Development in a New Species of Pennilabium yunnanense(Orchidaceae)

LI Lu1, ZHANG Jin1,2, LI Chu-Ran1, WANG Yan-Ping1,2, TAN Qing-Qin1,2, LUO Yan3   

  1. 1. Yunnan Academy of Biodiversity, Southwest Forestry University, Kunming 650224;
    2. School of Life Science, Southwest Forestry University, Kunming 650224;
    3. Department of Gardening and Horticulture, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303
  • Received:2019-07-01 Online:2020-03-05 Published:2020-03-06
  • Supported by:
    The National Natural Science Foundation of China(31260045,31460040);National survey of Chinese medicine resources of National Administration of Traditional Chinese Medicine(GZY-KJS-2018-004)

Abstract: Pennilabium J. J.Sm. is a newly recorded genus in China, including two species founded in Yunnan and Hainan. One of them is a new species of P.yunnanense. In this paper, floral morphology and pollina development in P.yunnanense were investigated. The column of a mature flower is short without column foot. Pollinarium unit is composed of two subglobose pollinia, stipe and viscidium. In the early stage, anther primordium is differentiated into a pair of lateral juxtaposed thecae. At the stage of microsporocyte, an incomplete sterile septum is formed adjacent to the inner anther wall between two thecae. During the microsporogenesis, the sterile septum becomes gradually degraded, resulting two pollinia with pore toward the inner anther wall disorganized. The hypodermal sporogenous cells produce 4-layered anther wall by periclinal divisions, including epidermis, endtothecium, middle layer, and a tapetum, which was of monocotyledonous type. Tapetum is uninuclear and secretory. Epidermis is not persistent, which becomes degraded as well as middle layer and tapetum. Fibrous thickenings occur on the entdothecium. Simultaneous cytokinesis results in tetrahedral and isobilateral microspore tetrads. Microspores undergo a mitosis leading to 2-celled pollen tetrads. Pollen tetrads arranged tightly and formed a subglobose pollinium in each theca. The embryological data on pollinia development of P.yunnanense could provide new insight for a better understanding of biodiversity and conservation in Orchidaceae.

Key words: microsporogenesis, male gametogenesis, Orchidaceae, pollinia development, Pennilabium yunnanense

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