排序方式： 共有2条查询结果，搜索用时 0 毫秒
1
1.
The present paper embodies the results of a karyotypic analysis for the
species Lycoris rosea Traub et Moldenke. The voucher specimen, J. Z. Lin 004 is pre-
served in the Herbarium of Hanchow Botanical Garden. The chromosome number in root
tip cells is found for the first time to be 22, and the karyotype is shown to be an asymme-
trical one with rod-shaped chromosomes. A photomicrograph, the karyotype and the idiog-
ram are shown in Figs. 1-2. According to Levan et aL.[5], the karyotype formula of the
species is 2n=22=22t. But based on the classification presented by Bose and Flory[1], the
karyotype formula should be expressed as 2n=22 =C22, and the chromosomes are all with
subterminal constrictions.
If regarding 11 as the basic number and centric fusion as the major tendency of karyo-
type evolution as proposed by Inariyama[2], Stebbins[6], and Jones[3,4] in particular, L. rosea
would be considered as one of the most primitive species in Lycoris from point of view of
karyotype evolution. Reciprocal translocations and centric fusions would give rise to V-sha-
ped chromosomes. Consequently, the successive decrease in chromosome number may have
taken place in the speciation of the genus under discussion. Yet further evidence seems ne-cessary for the verification of the speculation. 相似文献
2.
A karyotypic analysis of Lycoris longituba Y. Hsu et Fan was carried
out. The voucher specimen, Z. G. Mao 10501, is preserved in the Herbarium of Hangchow
Botanical Garden. The chromosome number in root tip cells of the species is found for the
first time to be 16, among which 6 are large, V-shaped with submedian primary constric-
tions, and the other 10 are short, rod-shaped with terminal primary constrictions. Photomi-
crograph of the chromosome complement and idiogram are given in Fig. 1-3 respectively.
The karyotype formula of the species is therefore 2n=16=6m+6t+4t (SAT) in the light
of the chromosomal terminology defined by Levan and al.[5]
Based on the view stressed by Jones[3] and Brandham[4], successive fusion of the ch-
romosomes should be taken as the essential mechanism for karyotype evolution and specia-
tion in Lycoris. Reciprocal translocation, with the loss of one of the centromeres, might be
the mechanism of origin for a V chromosome. It is, then, suggested that the decrease in ch-
romosome number as a result of fusion of the rods with terminal or subterminal primaryconstrictions has taken place in the speciation of L. longituba. 相似文献
1