Gallego F, Feuillet C, Messmer M, Penger A, Graner A, Yano M, Sasaki T, Keller B
Department of Resistance and Quality Breeding, Swiss Federal Research Station for Agroecology and Agriculture, Zürich, Switzerland.
Genome. 1998 Jun;41(3):328-36. doi: 10.1139/g98-024.
The wheat genome is large, hexaploid, and contains a high amount of repetitive sequences. In order to isolate agronomically important genes from wheat by map-based cloning, a simpler model of the genome must be used for identifying candidate genes. The objective of this study was to comparatively map the genomic regions of two wheat leaf rust disease resistance loci, Lr1 and Lr10, in the putative model genomes of rice and barley. Two probes cosegregating with the Lr1 gene on chromosome 5DL of wheat were studied. The rice sequences corresponding to the two probes were isolated and mapped. The two probes mapped to two different rice chromosomes, indicating that the organization of the region orthologous to Lr1 is different in rice and wheat. In contrast, synteny was conserved between wheat and barley in this chromosomal region. The Lrk10 gene cosegregated with Lr10 on chromosome 1AS in wheat. The rice gene corresponding to Lrk10 was mapped on rice chromosome 1, where it occurred in many copies. This region on rice chromosome 1 corresponds to the distal part of the group 3S chromosomes in Triticeae. The synteny is conserved between rice chromosome 1 and the Triticeae group 3S chromosomes up to the telomere of the chromosomes. On group 3S chromosomes, we found a gene that is partially homologous to Lrk10. We conclude that in the genomic regions studied, there is limited and only partially useful synteny between wheat and rice. Therefore, barley should also be considered as a model genome for isolating the Lr1 and Lr10 genes from wheat.
小麦基因组庞大，是六倍体，且包含大量重复序列。为了通过图位克隆从小麦中分离出具有重要农艺性状的基因，必须使用一个更简单的基因组模型来鉴定候选基因。本研究的目的是在水稻和大麦的假定模型基因组中，对两个小麦叶锈病抗性基因座Lr1和Lr10的基因组区域进行比较定位。研究了与小麦5DL染色体上Lr1基因共分离的两个探针。分离并定位了与这两个探针相对应的水稻序列。这两个探针定位于水稻的两条不同染色体上，表明与Lr1直系同源的区域在水稻和小麦中的组织方式不同。相比之下，在这个染色体区域，小麦和大麦之间的同线性是保守的。Lrk10基因与小麦1AS染色体上的Lr10共分离。与Lrk10相对应的水稻基因定位于水稻第1染色体上，在该染色体上有多个拷贝。水稻第1染色体上的这个区域对应于小麦族3S染色体组的远端部分。水稻第1染色体与小麦族3S染色体组之间的同线性一直保守到染色体的端粒。在3S染色体组上，我们发现了一个与Lrk10部分同源的基因。我们得出结论，在所研究的基因组区域中，小麦和水稻之间的同线性有限且仅部分有用。因此，大麦也应被视为从小麦中分离Lr1和Lr10基因的模型基因组。
