Kynast R G, Friebe B, Gill B S
Department of Agronomy & Plant Genetics, University of Minnesota, St. Paul 55108, USA.
Chromosome Res. 2000;8(2):133-9. doi: 10.1023/a:1009294519798.
A new gametocidal (Gc) factor was identified on chromosome 4Mg of Aegilops geniculata Roth. When transferred to Chinese Spring wheat, monosomic and disomic Triticum aestivum-Ae. geniculata chromosome 4Mg addition plants undergo regular first and second meiotic divisions. Male gametogenesis in disomic 4Mg addition plants also is normal. However, chromosome breakage and anaphase bridges were observed at ana/telophase of the first (29%) and second (11%) pollen mitosis in monosomic 4Mg addition plants. Gc-induced multicentric and ring chromosomes can be transmitted to the offspring and initiate breakage fusion bridge (BFB) cycles in dividing root tip meristem cells of the derived sporophytes. The fate of multicentric and ring chromosomes was analyzed in root meristems at different time intervals after seed germination. The majority of the BFB cycles ceased about 32 days after germination. Broken chromosome ends were healed either by the fusion of a centric and an acentric fragment forming terminal translocation chromosomes or as deficiencies or telocentric chromosomes. Lack of cytologically detectable telomeric repeats at the stabilized newly broken termini suggests that chromosome healing by addition of telomeric repeats may be a gradual process.
在节节麦（Aegilops geniculata Roth）的4Mg染色体上鉴定出一种新的杀配子（Gc）因子。当将其转移到中国春小麦中时，单倍体和二倍体普通小麦-节节麦4Mg染色体附加系植株的第一次和第二次减数分裂正常进行。二倍体4Mg附加系植株的雄配子发生也正常。然而，在单倍体4Mg附加系植株的第一次（29%）和第二次（11%）花粉有丝分裂的后期/末期观察到染色体断裂和后期桥。Gc诱导的多着丝粒染色体和环状染色体可传递给后代，并在衍生孢子体的根尖分生组织细胞分裂中引发断裂融合桥（BFB）循环。在种子萌发后的不同时间间隔，对根分生组织中多着丝粒染色体和环状染色体的命运进行了分析。大多数BFB循环在萌发后约32天停止。断裂的染色体末端通过着丝粒片段与无着丝粒片段融合形成末端易位染色体，或者以缺失或端着丝粒染色体的形式愈合。在稳定的新断裂末端缺乏细胞学上可检测到的端粒重复序列，这表明通过添加端粒重复序列进行染色体愈合可能是一个渐进的过程。
