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An integrated genetic and physical map of chromosome XIX in poplar
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Edité par CCSD -
International audience. Poplar was chosen as a model species for the sequencing of a first tree genome, since 2004 a draft genome sequence is available for a wild Populus trichocarpa individual named Nisqually-1. An integrated genetic and physical map has already been generated. However, the chromosome XIX remains unachieved. This chromosome carries many genes of interest, such as rust resistance, suitability for mychorization, root growth, and sex determination. An integrated genetic and physical map is needed to allow positional cloning of valuable genes. We propose to complete the physical map of this chromosome of 12Mb by using a concomitant reiterative approach of chromosome walking and genetic mapping. A 14X BAC library constructed from the individual P. trichocarpa (Clone 101-74) arranged in 3D pools was used as new genomic resource for chromosome walking. About 15 000 BAC ends were initially aligned to the sequence of Niqually-1's chromo- some XlX. About 70 BAC clones have been clearly assigned on the chromosome XlX, they are distributed into 13 main contigs. Extension of each contig, is under way with new PCR based markers developed from corresponding BAC ends. End sequence reads were also utilized to develop genetic markers to enhance genetic map resolution of the P. trichocarpa clone 101-74's chromosome XlX. Because poplar presents a high level of heterozygozyty, genetic markers were used to determine homolog origin for BAC clones.
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