作 者 ：Yu Hong, Huang Rui-fu
期 刊 ：植物分类学报 1994年 4期
Keywords:Nomocharis forestii,
Abstract:
Nomocharis forrestii Balf. f. from Zhongdian, Yunnan, was cytologically investi-
gated in this wrok. There were two cytotypes in N. forrestii populations. The reference
karyotype of A cytotype was 2n=24=2m (2SAT) +2sm+8st (4SAT) +12t (2SAT). In
this cytotype, there was no satellite in the long arms of the 3rd pair, which was homozy-
gous. The reference karyotype of B cytotype was 2n=24 = 2m (2SAT) + 2sm+8st
(2SAT) +12t (3SAT). In B cytotype, there was an obvious satellite in the long arm of one
chromosome in the 3rd pair, but no satellite in the long arm of the other. This was heterozy-
gous. The ratio between the cytotypes was approximately lA: 2B in the population. The
karyotype in N. forrestii was similar to that in the genus Lilium, 2n=24, particularly the
chromosomal morphology of m-chromosomes or sm-chromosomes. However, the secondary
constrictions of the m-chromosomes was more obvious and greater in N. forrestii.
Numerous aberrant karyotypes in N. forrestii were found in the somatic cells. The
structural aberrations include breakage, inversion (incl. pericentric inversion), translocation
(incl. Robertsonian translocation), deletion, somatic orossing over between the homologous
chromosomes, etc. In the aberrant karyotype (1), an obvious deletion took place in one
chromosome or unequal translocation took place in one chromosome of the 1st pair, and a
fragment was added to the long arm of one chromosome as a result of translocation in the
7th pair. A dicentric chromosome was found between two chromosomes from 8th and the
12th pair, which resulted in 2n=23. In aberrant karyotype (2), translocation or deletion
took place in the 5th, 6th, 7th and 10th pair. There were 4 B-chromosomes in the aberrant
cell. In the aberrant karyotype (3), the long arm of one chromosome was found to have a
deletion in the 6th pair. A dicentric chromosome was generated between two chromosomes
from the 9th and the 10th pair, which results in 2n=23. There was one B-chromosome in
the aberrant cell. In the aberrant karyotype (4), a pericentric inversion took place in the 1st
pair, and an unequal translocation occured between the 1st and the 6th pair, which changed
the first pair from m-chromosomes into st-chromosomes. The long arm of one chromosome
carried a remarkable deletion in the 8th pair. In the aberrant karyotype (5), a Robertsonian
translocation took place between two chromosomes from the 6th and 7th pair, and a frag-
ment was added to the long arm of one chromosome as a result of the translocation in the
l2th pair. In the aberrant karyotype (6), breakage occured near or at the centromere of one
chromosome of the 1st and the 6th pair, which resulted in 2n= 26. Before the breakage, the
unequal crossing over had taken place between the homologous chromosomes in the 1st and
6th pair, and an unequal translocation was found between two chromosomes from the 1st
and 6th pair. Accoding to statistics of aberrant cells, the chromosomal aberration took place
mainly in the 1st, 6th, 7th, 8th, 9th and 10th chromosomes, with rates of aberration 33-
37%. It is these chromosomes that often show polymorphism.
From above, the karyotype of N. forrestii, is under strong differentation. So the somat-
ic chromosome aberration with a high frequency is one of important factors in the intraspe-
cific differentiation in N. forrestii.