| Cauliflower is one of the most important vegetables in the world. It originated in the littoral countries of the Mediterranean. It was introduced into China in the middle of the 19th century, and now existed many genetic variances and formed plenty of local varieties and improved cultivars. Up to now, however, only a few molecular linkage maps and related molecular biology researches in cauliflower were published.This paper attempted to construct a single chromosome RFLP system. (1) In order to construct a genetic segregation population, 12 anther-derived plants of 4 cauliflower FIS were used as the sources to select parents with genetic polymorphism. (2) For the sake of constructing of single chromosome RFLP system, cauliflower variety, "Minghua 60 day", was used as material to micro-dissect and micro-clone single chromosome by the use of techniques of single chromosome micro-dissection and micro-amplification.(3) Using amplification products of dissected single chromosome as template, this study also engaged in the amplification of RGA homologous sequence, which created a new way for finding probes of single chromosome RFLP. Details are presented bellow:1. Analysis of genetic polymorphism of anther-derived plants in cauliflower FI using RAPD technique.1) The genomic DNA of 2 plants (code: AC07, AC 10) from the 12 anther-derived plants were used as templates, and 53 RAPD primers were identified. Results indicated that 32 RAPD primers could amplify clear bands. Among them, amplified products from 19 RAPD primers showed genetic polymorphism. The ratio of polymorphism of primers was 59.4%.2) The genomic DNA of all 12 anther-derived plants (code: AC01- AC12) were amplified by the 19 RAPD primers. We got total 138 clear DNA amplification bands from 10 RAPD primers, and selected five pairs of parents (10 plants) with high polymorphism (AC09 and AC12, AC08 and AC12, AC07 and AC12, AC04 and AC09, AC04andAC07).3) Cluster analysis of these 138 amplification bands showed that these plants could be clustered into 3 groups: AC01, AC02, AC03, AC04, AC10, AC11 and AC12 into the first group; AC05, AC06, AC07 and AC08 into the second group and AC09 into the third group. The first group could be divided into 2 sub-groups: AC01, AC02, AC03 and AC04 into asub-group; AC 10, AC 11 and AC 12 into another sub-group.2. Micro-dissection and amplification of single chromosome of cauliflower1) Using the root tip of cauliflower variety, "Minghua 60 day", as materials, 40 pieces of single chromosome of cauliflower were successfully isolated by the use of glass needles under micromanipulation equipment.2) The isolated single chromosomes were amplified by LA-PCR and DOP-PCR, respectively. Results showed that DNA fragments of LA-PCR products were much larger than that of DOP-PCR products. In addition, it was found that controlling contamination in LA-PCR was easier than that in DOP-PCR.3) Amplification products of the genomic DNA and the single chromosome were used as probes for southern blotting. Results showed that the amplifications from single chromosome actually came from the cauliflower genomic DNA.3. PCR-based cloning and analysis of NBS-LRR class resistance gene analogs from single chromosomal DNA in cauliflower1) Two degenerate oligonucleotide primer combinations, X3/Z7 and Y16/LP17, were used to amplify sequences of genomic DNA, respectively. Results indicated that only the PCR products of X3/Z7 showed a bright band of approximate 500bp. After endonuclease analysis of its clones, the clones could be divided into 12 groups, and one of the clone (hs01) was selected for sequencing. Blast showed that the sequence was RGA. This proved availabilities of primers X3/Z7 for amplifying the cauliflower RGA.2) The X3/Z7 were also used to amplify sequences from single chromosome amplified DNA. After endonuclease analysis of its clones, the clones could be divided into 7 groups. After sequencing, 5 sequences (candidate RGA) were gained, which were hs02, hs03, hs05, hs06, hs08.3) Pairwis...
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