Study On The Chromosomes Aberration Induced By The Gametocidal Chromosome 2C Derived From Aegilops Cylindrica

The purposes and significances of the present study are: 1. To produce a series of wheat-rye translocation lines by the mean of gametocidal chromosome 2C. 2. To determine if the chromosome breaks are unequal among homoeologous groups, and try to explore the law and frequency of the chromosomal changes induced by gametocidal gene. 3. To isolate a series of wheat and rye chromosomal deficiency lines, which are important materials for building high-density deficiency map and clone genes.The contents of the present study are:1. To study on the chromosomal aberration in wheat and rye chromosomes induced by the gametocidal chromosome 2C, which is derived from Aegilops cylindrica.(1) Designing the following hybridization combination: CS-R" X CS-2C" , their progenies - 2C monosomically added, are the basic materials for the study.(2) Determine the chromosome configuration of the somatic cells in F] by C-banding to ensure the materials are available. We also observed the behaviors of the PMC of F1, and show abnormal. We deduce that the abnormal chromosome paring is attribute to the gametocidal chromosome 2C.(3) To identify the chromosome aberration of F2 by integrated methods, and acquired the chromosomal deficiency, translocation, iso-chromosome and dicentremere chromosome. Furthermore, we statistic the law and frequency of aberrations.(4) we isolated 10 wheat-rye translocation lines, 1 translocation line within wheat genomes. Besides, we isolated 12 rye chromosomes deficiency lines, 54 wheat chromosome deficiency lines. All the deficiency lines are important materials for building deficiency map of rye and for gene clone.2 To study the effect of the gametocidal chromosome 2C (derived from Aegilops cylindryca) on meiosis and mitosis of pollen grains of triticale.(1) Because both the Hexaploid and Octoploid triticale contain a whole set of rye chromosomes, we expect to determine if there exist orientation in inducing alien chromosomes aberration by the gametocidal chromosomes 2C by designing the hybridization combination of crossing triticale with CS-2C" .(2) In the process of meiosis in hybrid FI, we observed a large number of lagging chromosomes, chromosome fragments, ring chromosomes and chromosome bridges in anaphase I and II. In dispores and tetraspores, there exists many micronucleus, some of the tetraspores form paraspores.(3) Observation on the mitotic process of the pollen grains didn't show any abnormal phenomena.Discussion about the gametocidal chromosome 2C(1) we combine the results of the present study with the study on the effect of the gametocidal chromosome 2C on Elytrigia, we did it previously, we share the viewpoint that the abnormal meiosis of PMC in F] is caused by the gametocidal chromosome 2C.(2) discussing about the exactly phase of the gametocidal chromosome functions:In this study, we observed that the first and the second meiotic divisions in all lines were cytologically abnormal, while the postmeiotic mitoses were normal. The morphology of the chromosome fragments suggests that the Gc genes induce chromosome breaks in the process of meiotic division or even earlier instead of in the GI phase prior to DNA synthesis of the first postmeiotic mitosis, reported by Shuhei Nasuda (1998).(3) we summarized based on experimental phenomena observed that the gametocidal chromosome possesses the following traits, which differ from the physical and chemical factors: It has high efficiency; The aberrant types of chromosome induced by Gc are extremely complicated, representing as chromosome deficiency, translocation, isochromosome, dicetremere chromosome and ring chromosome and so on.(4) The aberrant chromosome occurs unequally among homoeologous groups, i.e., Gc induces chromosome breaks with certain orientation.