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云南山茶花四倍体的首次发现及其科学意义

顾志建   

  • 收稿日期:1900-01-01 修回日期:1900-01-01 出版日期:1997-03-10 发布日期:1997-03-10
  • 通讯作者: 顾志建

The Discovery of Tetraploid Camellia reticulata and Its Implication in Studies on the Origin of This Species

Gu Zhi-jian   

  • Received:1900-01-01 Revised:1900-01-01 Online:1997-03-10 Published:1997-03-10
  • Contact: Gu Zhi-jian

摘要:

本文对分布于云南和四川金沙江河谷的云南山茶花C. reticulata及其两个近缘种(怒江山茶C.saluenensis和西南山茶C.pitardii)进行了细胞学研究。34个居群的云南山茶花中,21个居群是四倍体类型(2n=60),11个居群是六倍体类型(2n=90),另2个居群为二倍体(2n=30),云南山茶花的四倍体类型为首次发现,并且进行了核形态研究。四倍体和六倍体的花粉母细胞减数分裂染色体构型在大多数居群都为二价体(四倍体中30个二价体,六倍体中45个二价体),少数居群或是个体除二价体为主外还出现单价体和四价体,六倍体类型没有出现六价体构型。根据减数分裂的构型,我们认为,四倍体和六倍体分别为异源四倍体和异源六倍体,少数四价体的存在表明染色体有部分同源性。所有四倍体和六倍体的体细胞间期核特征和前期染色体形态特征基本相似。中海拔(1800m)以上的四倍体的云南山茶花外部形态特征与六倍体类型比较相似,而低海拔(1100~1800 m)的四倍体类型的外部形态特征则有些不同,但核形态结构是比较相似的。四倍体与六倍体类型地理分布是连续的,并与近缘的二倍体种怒江山茶、西南山茶重叠分布。

关键词: 金沙江河谷, 云南山茶花, 核形态, 起源

Abstract:

Camellia reticulata and its two allied species, C. saluenensis and C. pitardii,all from the Jinshajiang Valley of Yunnan and Sichuan, were cytologically studied in this work. Among 34 populations of C.reticulata studied here, 21 were found to be tetraploids (2n=60), 11 hexaploids (2n = 90), and the remaining two diploids (2n = 30). Tetraploid was reported in C. reticulata for the first time and its karyomophology was studied. In meiosis of pollen mother cells of the tetraploids and the hexaploids, only bivalents were observed in most of the populations, although in several populations or individuals a few univalents or tetravalents appeared. In the hexaploids, hexavalents were not observed. Thus, the meiotic chromosome cofigurations showed that the tetraploids and hexaploids in C.reticulata allopolyploids, and the appearance of a few tetravalents in some populations might indicate
homology of chromosomes in different genomes to some extent. The characteristics of the resting nuclei and the prophase chromosomes of all the tetraploids and hexaploids were quite similar to each other. The tetraploids of C.reticulata from the localities with the altitude of over 1800 m were gross-morphologically similar to the hexaploids, but those growing between 1100 ~1800 m were different to some extent from the hexaploids. In geographical distribution, the tetraploids and the hexaploids were continuous, and overlapped with C. saluenensis and C. pitardii.

Key words: Jinshajiang Valley, Camellia reticulate, Karyomorphology, Origin