极危植物九龙山榧的大小孢子发生和雌雄配子体发育研究  

Microsporogenesis, megasporogensis and development of male and female gametophytes of Torreya jiulongshanensis, a critically endangered plant

作　　者：冉钰岑 何芳 刘菊莲 郑子洪 郑伟成 胡江琴[2] 金孝锋 RAN Yucen;HE Fang;LIU Julian;ZHENG Zihong;ZHENG Weicheng;HU Jiangqin;JIN Xiaofeng(State Key Laboratory of Subtropical Silviculture/Zhejiang Provincial Key Laboratory of Forest Aromatic Plants-based Healthcare Functions,College of Forestry and Biotechnology,Zhejiang A&F University,Hangzhou 311300,Zhejiang,China;School of Life and Environment Sciences,Hangzhou Normal University,Hangzhou 311121,Zhejiang,China;Administration Center of Zhejiang Jiulongshan National Nature Reserve,Suichang 323300,Zhejiang,China)

机构地区：[1]浙江农林大学,林业与生物技术学院,省部共建亚热带森林培育国家重点实验室/浙江省森林芳香植物康养功能研究重点实验室,浙江杭州311300 [2]杭州师范大学生命与环境科学学院,浙江杭州311121 [3]浙江九龙山国家级自然保护区管理中心,浙江遂昌323300

出　　处：《浙江农林大学学报》2022年第5期940-949,共10页Journal of Zhejiang A&F University

基　　金：浙江省林业局资助项目(2017-2020);国际植物园保护联盟(BGCI)资助项目(GTC/2022/021);国家自然科学基金资助项目(32070218)。

摘　　要：【目的】九龙山榧Torreya jiulongshanensis为浙江特有的古老孑遗植物,数量极少,为国家Ⅱ级重点保护野生植物,也被列为浙江省极小种群保护植物。系统观测九龙山榧大、小孢子的发生和雌、雄配子体的发育过程,有助于发现其配子是否发育异常及导致结籽率低下的原因。【方法】以九龙山榧模式产地的雌、雄植株为研究对象,通过定期观测和取样,采用石蜡切片法对其大、小孢子的发生,雌、雄配子体的发育过程进行切片、染色和观察。【结果】(1)小孢子叶球于8月中旬开始分化,8月下旬分化形成次生造孢细胞,11月中旬形成小孢子母细胞,翌年2月下旬进入减数分裂期,3月中旬形成游离小孢子细胞,于3月末逐渐成熟;成熟花粉粒为双核,无气囊。小孢子囊的发育类型为基本型,孢质分裂方式为同时型,四分体有四面体形和左右对称形。(2)雄配子体从3月中下旬开始发生,到7月底形成精子,整个过程历时约4个月。(3)翌年3月下旬,大孢子叶球每个苞叶的叶腋基部直立着生2枚胚珠;大孢子母细胞于4月下旬经过减数分裂Ⅰ和减数分裂Ⅱ形成4个直列大孢子,5月中旬珠孔端的3个大孢子退化,合点端的大孢子最终发育成为雌配子体。(4)九龙山榧有2个单生型椭圆形的颈卵器,从传粉到受精历时约7个月。【结论】九龙山榧雌雄生殖系统发育的周期均较红豆杉科Taxaceae其他种更长,其冗长的生殖周期、复杂的生殖过程和雌性生殖系统发育明显滞后于雄性生殖系统,加之种群个体数量极度稀少(1雌株、2雄株)是造成结籽率低下、自然更新困难的主要原因。[Objective] Torreya jiulongshanensis, an ancient relict plant endemic to Zhejiang Province, is a national Class Ⅱ key protected wild plant and also listed as a protected plant of extremely small population in Zhejiang Province. The purpose of this study is to systematically observe the occurrence of megaspores and microspores of T. jiulongshanensis, as well as the development of male and female gametophytes, so as to find out whether the gametes are abnormal and the reasons for low seed-setting rate. [Method] The male and female individuals of T. jiulongshanensis from the type locality were collected as the research objects. Through regular observation and sampling, the occurrence of megaspores and microspores and the development of female and male gametophytes were sectioned, stained and observed by paraffin sectioning method. [Result](1) The microsporophyll differentiated in mid-August, differentiated into secondary sporogenesis cells in late August and formed microspore mother cells in mid-November. In late February of the next year, it entered the meiosis stage, formed free microspore cells in mid-March, and gradually matured at the end of March. The mature pollen grains were binucleate without air sacs. The development type of microsporangium was basic type, and the spore division model was simultaneous type. The tetrad had tetrahedral and zygomorphic forms.(2) Male gametophytes began to develop in mid-to-late March, and formed sperm at the end of July. The whole process lasted about 4 months.(3) In late March of the next year, 2 erect ovules were born at the base of leaf axils of each bract in megasporophyll. In late April, the megaspore mother cell underwent meiosis Ⅰ and Ⅱ, and formed 4 linear megaspores. In mid-May, 3 megaspores at the micropylar end degenerated and the megaspores at the chalazal end finally developed into female gametophytes.(4) T. jiulongshanensis had 2 solitary oval archegonia, which lasted about 7 months from pollination to fertilization. [Conclusion] The development cycle of m

关 键 词：九龙山榧 小孢子发生 雄配子体 大孢子发生 雌配子体 

分 类 号：S718.4[农业科学—林学]