Dixon M S, Hatzixanthis K, Jones D A, Harrison K, Jones J D
Sainsbury Laboratory, John Innes Centre, Colney Lane, Norwich, NR4 7UH, United Kingdom.
Plant Cell. 1998 Nov;10(11):1915-25. doi: 10.1105/tpc.10.11.1915.
The tomato Cf-2 and Cf-5 genes confer resistance to Cladosporium fulvum and map to a complex locus on chromosome 6. The Cf-5 gene has been isolated and is predicted to encode a largely extracytoplasmic protein containing 32 leucine-rich repeats (LRRs), resembling the previously isolated Cf-2 gene, which has 38 LRRs. Three haplotypes of this locus from Lycopersicon esculentum, L. pimpinellifolium, and L. esculentum var cerasiforme were compared, and five additional homologs of Cf-5 were sequenced. All share extensive sequence identity, particularly within the C-terminal portions of the predicted proteins. In striking contrast to the Cf-9 gene family, six of seven homologs in the Cf-2/Cf-5 gene family vary in LRR copy number, ranging from 25 to 38 LRRs. Cf-5 and one adjacent homolog differ by only two LRRs. Recombination events that vary the LRR copy number in this region could provide a mechanism for the generation of new specificities for recognition of different ligands. A recombination breakpoint between the Cf-2 and Cf-5 loci was fully characterized and shown to be intragenic.
番茄Cf - 2和Cf - 5基因赋予对番茄叶霉病的抗性，并定位到6号染色体上的一个复杂位点。Cf - 5基因已被分离出来，预计编码一种主要位于胞外的蛋白质，含有32个富含亮氨酸重复序列（LRR），类似于先前分离的Cf - 2基因，后者有38个LRR。比较了来自番茄、醋栗番茄和樱桃番茄的该位点的三种单倍型，并对另外五个Cf - 5同源基因进行了测序。所有这些基因都具有广泛的序列同一性，特别是在预测蛋白质的C末端部分。与Cf - 9基因家族形成鲜明对比的是，Cf - 2/Cf - 5基因家族的七个同源基因中有六个在LRR拷贝数上有所不同，范围从25到38个LRR。Cf - 5和一个相邻的同源基因仅相差两个LRR。该区域中改变LRR拷贝数的重组事件可能为产生识别不同配体的新特异性提供一种机制。Cf - 2和Cf - 5位点之间的一个重组断点已被完全表征，并显示为基因内的。
