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FISH analysis of intraspecific aneuploids in Carex blepharicarpa

睑果苔草种内非整倍体的 FISH 分析

基本信息

批准号：
12640687
负责人：
HOSHINO Takuji
金额：
$ 0.58万
依托单位：
Okayama University of Science
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

项目摘要

The intraspecific aneuploids are found in many species of the genus Carex. The aneuploids were thought to arise easily by chromosome fission or fusion, because all species of Carex have diffused centromeric chromosomes. A consecutive chromosome numbers, 2n=26～32 are reported in C. blepharicarpa. In this study, meiotic configurations of intraspecific aneuploids of C. blepharicarpa collected from 21 populations in Japan were analyzed, and chromosomal localization of 18S rDNA were determined by fluorescent in situ hybridization (FISH).1. Meiotic chromosome configurations of intraspecific aneuploidsAt meiotic metaphase I, seven kinds of intraspecific aneuploids, 2n=26～32 were found, and one to three heteromorphic chain trivalents were observed in almost all individuals. Heteromorphic trivalents comprising large, medium and small chromosomes were prevalent. Homomorhpic trivalents, which are thought to be originated from chromosome duplications caused by unreduced gametes, were found in three individuals with 2n=41,46, and 64. The high frequency of heteromorphic trivalents in this species indicates that most aneuploidy probably results from fission and/or fusion of chromosomes.2. FISH analysis of intraspecific aneuploidsThe 18S rDNA was hybridized to the terminal regions of two large and two medium bivalents. But, trivalent and univalent chromosomes had no 18S rDNA signal. These results show that the aneuploids of C. blepharicarpa probably maintained within population by unequal divisions of trivalents or univalents with no 18S rRNA gene.

种内非整倍体存在于许多种苔属植物中。非整倍体被认为很容易通过染色体分裂或融合产生，因为所有种类的苔属植物都有扩散的着丝粒染色体。据报道，双眼皮草的染色体数为2n=26~32。本研究分析了日本21个种群的种内非整倍体的减数分裂构型，并采用荧光原位杂交（FISH）技术测定了18S rDNA的染色体定位。种内非整倍体的减数分裂染色体构型在减数分裂中期，发现七种种内非整倍体，2n=26~32，几乎所有个体都有1 ~3个异型链三价。由大、中、小染色体组成的异型三价体普遍存在。同源三价体被认为起源于未还原配子引起的染色体复制，在3个2n=41、46和64的个体中发现。异型三价的高频率表明，大多数非整倍性可能是由染色体的裂变和/或融合引起的。种内非整倍体的FISH分析将18S rDNA杂交到两个大二价体和两个中二价体的末端区域。而三价和单价染色体没有18S rDNA信号。这些结果表明，在没有18S rRNA基因的情况下，黄颡鱼的非整倍体可能是通过三价体或单价体的不均等分裂而维持的。