Identification And Meiosis Observation Of The New Chinese Cabbage Germplasm With Cabbage Chromosomes

In order to create the alien addition lines, the BC₁ plants devived from the backcrosse between the Chinese cabbage-cabbage allotriploid (ACC,2n=3x=29) and diploid Chinese cabbage (AA, 2n=2x=20) and their selfing progenies BC₁F₂ plants are used as studying materials. Two monosomic addition lines, one translocation line, one disomic addition line and two double alien monosomic addition lines are obtained by routine planishing technique , karyotype analysis and SSR molecular marks. And their morphologic, cytologic and reproductive characters are studied. This study provids basic material for the alien substitution lines and the translocation lines and also help to research the relative of A and C genomes, gene mapping and expression and the genetic improvement of varietices. The main results are showed as follows:1. The chromosome number of BC₁ was identified by counting chromosomes of tipced at mitosis, and the chromosome number of BC₁F₂ was identified by counting chromosomes of PMC at meiosis anaphase I. The rate of plants with 21 chromosomes and 22 chromosomes identified from 98 plants of BC₁ and 16 plants of BC₁F₂ was 4.08% and 5.10%, 12.5% and 12.5% respectively. The chromosome number of most plants was 23 to 24,with rate 55.10% in BC₁ and 31.25% in BC₁F₂.2. The field traits of BC1F2 plants with the same chromosome number showed multiplicity. The plants with extra chromosomes seemed like the parent cabbage in certain aspects, which would help to identify the type of addition chromosome according to field characters.3. Three monosomic addition lines with cabbage chromosome 2 and 4 , one disomic alien addition line with cabbage chromosome 2 and two double alien monosomic addition lines with cabbage chromosome2,4 and cabbage chromosome 4,9 were obtained by karyotype analysis. The field characters of the plants obtained were observed. The results showed that the alien addition lines seemed like the parent cabbage in certain aspects comparing with the diploid parent Chinese cabbage. And the characters of the plants with different cabbage chromosomes were very different. The field characters of two plants both with cabbage chromosome 4 were very different, and the results from SSR molecular marks of them showed that one of them may be a translocation line. 4.The PMC meiosis behavior of the plants obtained showed that: 1)To the plants with 21 chromosomes AA+C_2II,AA+C_4I,AA+C_4T, the chromosome configuration at diakinesis was mainly 10II+I, few of them were 9II+III. The form_I of chromosome separation at anaphase I was mainly 11-10, and the form of chromosome separation at anaphase II was mainly 11-10-11-10,one or two lagging chromosomes appeared in few cells. 2) To the disomic alien addition lines with 22 chromosomes AA+C_2D, the chromosome configuration at diakinesis was 11II; chromosomes moved to the equator plank at metaphase I ; the form of chromosome separation at anaphase I was mainly 10-2-10,and the form 11-11 occurred in few cells because of the lagging chromosomes. 3) To the double alien monosomic addition lines with 22 chromosomes w42 and e45, the chromosome configuration at diakinesis was mainly 10II+I+I, and multiple forms of chromosome separation at anaphase I, including 11-11,12-10 and 10-2-10 were deserved. 4) To the plants with more than 22 chromosomes, there were many formations of chromosome synapsis at diakinesis. The rate of multivalents was increased distinctly, which led to more lagging or losing chromosomes. The above separation formation indicated the multiformity.