Hunger Sandra, Di Gaspero Gabriele, Möhring Slike, Bellin Diana, Schäfer-Pregl Ralf, Borchardt Dietrich C, Durel Charles-Eric, Werber Martin, Weisshaar Bernd, Salamini Francesco, Schneider Katharina
Max Planck Institut für Züchtungsforschung, Carl von Linné Weg 10, 50829 Köln, Germany.
Genome. 2003 Feb;46(1):70-82. doi: 10.1139/g02-106.
Sequence conservation among resistance genes (R genes) was exploited to identify 47 R gene analogues (RGAs) from sugar beet (Beta vulgaris L.). Using degenerate primers, 11 RGAs were amplified from genomic DNA and 7 from leaf or beet cDNA. Twenty-nine were selected from an EST sequencing program. Twenty-one RGAs contained structures similar to the nucleotide binding site (NBS)--leucine rich repeat (LRR) domain, a motif commonly found in several R genes. Among the remaining RGAs, 19 revealed similarity to the serine (threonine) protein kinase domain of R genes, 4 showed features related to the LRR region of the rice disease resistance gene Xa21, 1 RGA resembled the sugar beet nematode resistance gene Hs1pro-1, and 2 had homologies to other gene products associated with disease resistance. For 20 EST-derived RGAs, transcript levels were compared in leaf and root tissue revealing organ-specific transcription in 7 cases. Thirty-three RGAs were spread over all nine sugar beet chromosomes, except for a cluster of nine closely linked RGAs on chromosome 7. The analysis of linkage between RGAs and loci for rhizomania and Cercospora resistance identified alleles associated with resistance in both cases.
利用抗性基因（R基因）间的序列保守性，从甜菜（Beta vulgaris L.）中鉴定出47个R基因类似物（RGA）。使用简并引物，从基因组DNA中扩增出11个RGA，从叶片或甜菜cDNA中扩增出7个。29个是从EST测序计划中挑选出来的。21个RGA含有与核苷酸结合位点（NBS）-富含亮氨酸重复序列（LRR）结构域相似的结构，这是几种R基因中常见的基序。在其余的RGA中，19个与R基因的丝氨酸（苏氨酸）蛋白激酶结构域相似，4个显示出与水稻抗病基因Xa21的LRR区域相关的特征，1个RGA类似于甜菜抗线虫基因Hs1pro-1，2个与其他抗病相关基因产物具有同源性。对于20个EST衍生的RGA，比较了叶片和根组织中的转录水平，发现7个案例中存在器官特异性转录。33个RGA分布在所有9条甜菜染色体上，除了第7号染色体上一组9个紧密连锁的RGA。对RGA与根瘤病和尾孢菌抗性位点之间的连锁分析，在这两种情况下都鉴定出了与抗性相关的等位基因。
