睡莲科的核型分析及其分类学位置的探讨

STUDY ON THE KARYOTYPE ANALYSIS OF NYMPHAEACEAE AND ITS TAXONOMIC POSITION

本文对睡莲科6属6种代表植物的核型进行了研究,并探讨了它的分类学位置。结果如下:莲2n=16=9sm+4m+3st;王莲2n=24=8sm+8m+8T;蓝睡莲2n=28,可配成14对,染色体小,第1号染色体上有2条随体;萍蓬草2n=34=18m+16sm;芡实2n=58,可配成29对,染色体小,第1号染色体有2条随体;莼菜2n=72,可配成36对,染色体按大小可分成大、中、小三个类别。除莲外,其它5种植物的核型为首次报道。莼菜的体细胞染色体数目2n=72和国外报道的2n=80不相一致。莲的染色体以及形态学特征和其它睡莲科分类群显著不同,可将其从睡莲科中独立出来,并成立莲科和莲目。原归属于睡莲科的分类群仍组成睡莲目,并分别置于莼菜科和睡莲科。

The present paper reports the karyotypes of six species in the family Nymphaeaceae (sensu lato) , and discusses its taxonomic position. Results of the karyotype analysis are as follows: (1) Nelumbo nucifera Gaertn. was found to have the karyotype 2n = 16 = 9sm-f-4m+3st, which belongs to 2B type. There was one heterozygous pair and one pair of large subterminal chromosomes in the complement. (2) Victoria cruzuma Orbign. was shown to have the karyotype 2n = 24 = 8sm + 8m + 8T, which belongs to 2A type. The chromosomes were the largest in the Nymphaeaceae. (3) Nymphaea stellata Willd. was' of 2n = 28. No. 1 chromosome possessed two satellites. The chromosomes were the smallest in the Nymphaeaceae. (4) Nuphar pumilum (Timm. ) DC. had the karyotype 2n=34 = 18m + 16sm, which belongs to 2A type. One satellite was on No. 8 chromosome and the other was easily detached (5) Euryale ferox Salisb. ex Konig et Sims, was of 2n = 58. The 58 chromosomes were in 29 pairs. Its chromosomes were small. No. 1 chromosome possessed two satellites. (6) Brasenia schreberi J. F. Gmel. was shown to have 2n = 72. The 72 chromosomes were in 36 pairs, which could be classified into 4 pairs of large chromosomes, 12 pairs of medium-sized ones and 20 pairs of small ones. Three satellites could be seen in some karyotypes. Except N. nucifera, the karyotypes of all the species are first reported. The great differences in the karyotype and morphological characteristics between Nelumbo and the other members of the Nymphaeaceae suggest that the Nymphaeaceae (sensu lato) be di- vided into two separate orders, namely Nelumbonales and Nymphaeales. Nelumbonales contains a single family Nelumbonaceae and a monotypic genus Nelumbo, while the other plants belonging to the Nymphaeaceae which constitute the order Nymphaeales. Nymphaeales may also be divided into two separate families, Cabombaceae and Nymphaeaceae. Cabombaceae containing Brasenia and other genera is the most primitive in the Nymphaeales. Nymphaea, Euryale, Victoria and Nuphar are included in the Nymphaeaceae.