Bonas U, Stall R E, Staskawicz B
Department of Plant Pathology, University of California, Berkeley 94720.
Mol Gen Genet. 1989 Jul;218(1):127-36. doi: 10.1007/BF00330575.
The avirulence gene avrBs3 from Xanthomonas campestris pv. vesicatoria was cloned and found to be localized on a self-transmissable plasmid. Genetic analysis of an avrBs3 insertion mutation revealed that avrBs3 constitutes a single locus, specifying the resistant phenotype on pepper plants. Southern blot experiments showed that no DNA sequences homologous to avrBs3 were present in other races of X. c. pv. vesicatoria, which are unable to induce a hypersensitive reaction on ECW-30R. However, the DNA of several different pathovars of X. campestris hybridized to the avrBs3 probe. A deletion analysis defined a region of 3.6-3.7 kb essential for avrBs3 activity. The nucleotide sequence of this region was determined. A 3561 nucleotide open reading frame (ORF1), encoding a 125,000 dalton protein, was found in the 3.7 kb region that was sufficient for avrBs3 activity. A second long ORF (2351 nucleotides) was identified on the other strand. A remarkable feature of both ORFs is the presence of 17 direct repeats of 102 bp which share 91%-100% homology with each other.
从野油菜黄单胞菌疮痂致病变种中克隆出无毒基因avrBs3，发现其定位于一个自我传递质粒上。对avrBs3插入突变体的遗传分析表明，avrBs3构成一个单一基因座，决定辣椒植株上的抗性表型。Southern杂交实验表明，在野油菜黄单胞菌疮痂致病变种的其他小种中不存在与avrBs3同源的DNA序列，这些小种无法在ECW - 30R上诱导过敏反应。然而，野油菜黄单胞菌几个不同致病变种的DNA与avrBs3探针杂交。缺失分析确定了一个对avrBs3活性至关重要的3.6 - 3.7 kb区域。测定了该区域的核苷酸序列。在对avrBs3活性而言足够的3.7 kb区域中发现了一个3561个核苷酸的开放阅读框（ORF1），编码一个125,000道尔顿的蛋白质。在另一条链上鉴定出第二个长开放阅读框（2351个核苷酸）。两个开放阅读框的一个显著特征是存在17个102 bp的直接重复序列，它们彼此之间具有91% - 100%的同源性。
