Cytogenetic Research Of Chinese Cabbage-cabbage Alien Addition Lines

In order to establish a set of Chinese cabbage-Cabbage monosomic alien addition lines, the backcross BC₁ between allotiplid hybrids(AAC) and Chinese cabbage(AA) and its selfing progenies BC₁F₂ are used as studying materials. Morphology and cytology of the plants are studied. Four monosomic addition lines and two double alien addition lines are screened and identified by karyotype analysis from BC₁. This study provids a chance for carring out the genetic improvement of Chinese cabbage, builts a basic for creating alien substitution and translocation lines. It also helps to locate the alien genes on the specific chromosome and provids the genetic materials for researching the relationship between A and C genomes.The main results are shown as follow:1. The BC₁ and BC₁F₂ were identified by taking count of the chromosome number at mitosis metaphase and at meiosis metaphase I or anaphase I . The chromosome number of BC₁ varied from 20～29, the majority of those aneuploids were 2n=23～24, the ratios of the plants with 20 chromosomes , 21 chromosomes and 22 chromosomes were 9.68%, 6.54% and 9.68% respectively, at the same time the ratios of the plants with 23～24 chromosomes reached 56.45%, the ratios of the plants with 25～26 chromosomes and 27～28 chromosomes reached 14.52% and 3.22% respectively. The chromosome number of 19 BC₁F₂ plants was 2n=20 ,with a regular meiosis behavior.2. The field characters of BC₁F₂ plants showed multiplicity although they had the same chromosomal number, two of them seemed like the parent cabbage in floral organs. All of those performances were possildly arised from translocation of alien chromosomes.3. Four monosomic addition lines AA+C₁I,AA+C₂I,AA+C₅I and AA+C₈I added chromosome 1,2,5,8 of cabbage respectively and two double alien addition lines S₈ which added chromosome 2 and 6, and S₃₉ which added chromosome 6 and 7 were identified and obtained from BC₁ by karyotype analysis at mitosis.4. All of the alien addition lines were obviously different in morphological characters.The lines AA+C₁I and AA+C₅I appeard similar to Chinese-cabbage in morphology but AA+C₁I flowered early. And there were some plants ,like AA+C₂I,AA+C₈I,S₈ and S₃₉ seemded similar to cabbge in leafycolor, leafycharacters, floral organs. The lines AA+C₂I had dark and green and smooth leaf with wax at grey-white leaf back.The inflorescence and floral organs of AA+C₈I looked like cabbage. The leaf of S₈ was dark-green and be mispherical. S₃₉ had dark-green smooth leaf.5.The pollen characters of four monosomic alien addition lines and two double monosomic alien addition lines were further observed. The results showed that there were siginificantly differences in pollen amount between alien addition lines and diploid parent Chinese-cabbage. The relativity of the pollen amount and viability was tested. The correlation between the pollen regularity and pollen viability was significantly.6.The characteristics of meiosis division for the monosomic alien addition lines were observed, The chromosome configurations at diakinesis could be divided two types 10â…¡+â… and 9â…¡+1â…¢. They maily formed distributions of 10-11 and 10-1-10 at anaphaseâ… , distributions of 11-10-11-10,10-10-2-10-10,10-10-11-10-1 at anaphaseâ…¡; To the double monosomic alien addition lines, the chromosome configurations at diakinesis during meiosis division may be classed three types 10â…¡+2â… ,9â…¡+â…¢+ I and 11â…¡. They maily formed distributions of 10-12,11-11,10-2-10,10-1-11,10-11 at anaphaseâ… and 11-11-10-10,10-10-10-11,10-10-10-10 at anaphaseâ…¡.