| The chromosome A09, is one of the longest among A-genome chromosomes and carries genes for major agronomical traits, such as seed size, seed coat color, and glucosinolate and fat synthesis in Brassica species. Therefore, dissecting this chromosome is of great scientific and practical significance.In this study, markers S121-Ⅰ-1、S121-Ⅰ-2、S59-6、S134-16、S121-Ⅱ-2、B021I11-1、 H016P07-2、Niab047, which located on chromosome A09of B. juncea, were used to screen ZBjuH BAC library as a starting point to build BAC contigs, BAC-ends sequencing technology and PCR walking screening were used for further bidirectional extension.725BACs were screened out, end sequence of315BACs were determined, and564BESs were gained,467pairs of primers were designed, of which250according to BESs,189STS primers according to homology B. rapa sequence,21STS primers according to unigene sequence in Sichuan Yellow-seed acquired by RNA-seq technology. About6.3Mb BAC contings in length in total were constructed.The BAC contings were corresponding to six homologous regions of B. rapa genomic sequence, Scaffold000045、Scaffold000081、Scaffold000040、Scaffold0000059、 Scaffold000169、Scaffold000134、Scaffold000145, as revealed by BLAST against BRAD database. Although a conserved region, Scaffold000045to Scaffold000040, was found between B. juncea, B. rapa and B. napus, comparison to B. rapa in scaffold order showed that the chromosome A09has undergone significant structural rearrangements from Scaffolds0000134to Scaffolds0000145, Scaffolds0000059has been reversed, Scaffolds0000169previously unanchored to a chromosome has been located next to the scaffolds000059in B. juncea, as found in B. napus, indicating that the chromosome A09has undergone different structural rearrangements during allopolyploidization of B. juncea and B. napus. These results have laid a foundation for construction of physical map of chromosome A09of B juncea and better understanding of evolution of the Brassica A09chromosome. |
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