Cereal Research Centre, Agriculture and Agri-Food Canada, Winnipeg, Manitoba, Canada.
Theor Appl Genet. 2010 Jul;121(2):373-84. doi: 10.1007/s00122-010-1316-7. Epub 2010 Mar 30.
Leaf rust resistance gene Lr34 is likely the most important leaf rust gene characterized to date. It has been characterized as an adult plant resistance gene and is known to enhance the resistance of other leaf rust resistance genes and to condition resistance to a number of other diseases. Located on chromosome 7D, this gene was identified to be one of six co-located genes of which, an ABC transporter was shown to be the only valid candidate. Ten new molecular markers were developed spanning the Lr34 locus, including six novel microsatellite markers (cam), one insertion site-based polymorphism marker (caISBP), two single nucleotide polymorphisms (caSNP), and one gene-specific marker (caIND). Using these new markers and others that were previously published, a comparative fine map of the locus was constructed from five segregating populations representing 1,742 lines. Identification of a susceptible line with a recombination in the 4.9 kb interval between caSNP4 located in the ABC transporter gene and cam8 located just upstream of this gene provided further evidence to support the identity of the ABC transporter as Lr34 by ruling out four of the adjacent genes. Originally, three mutations forming two haplotypes had been described for the ABC transporter gene. A third combination of the three mutations and an additional rare mutation in exon 22 were subsequently described. We identified an additional novel mutation in exon 10 that would cause a frameshift and is likely non-functional. This mutation was only found in Lr34- lines and constituted a novel molecular haplotype. Characterization of two germplasm collections of 700 Triticum aestivum lines permitted us to gain an understanding of the frequency of the ABC haplotypes characterized to date and their distribution in germplasm from and around the world. In addition to the four haplotypes previously described, a fifth haplotype was found in two of the 700 lines from the germplasm collections. These lines displayed the deletion in indel 11 characteristic of Lr34+ lines, but are likely susceptible to leaf rust. Mapping and haplotyping data suggest that of all the markers described herein, marker caIND11 is the best diagnostic marker for marker-assisted selection of Lr34 because it is co-dominant, robust and with the exception of 2/700 lines, it is highly diagnostic. Other markers are also described to provide alternatives for laboratories with different technologies.
叶锈病抗性基因 Lr34 可能是迄今为止鉴定的最重要的叶锈病基因。它被鉴定为成株期抗性基因,已知可增强其他叶锈病抗性基因的抗性,并可控制多种其他疾病的抗性。该基因位于 7D 染色体上,被鉴定为六个共定位基因之一,其中 ABC 转运蛋白是唯一的有效候选基因。开发了跨越 Lr34 基因座的 10 个新的分子标记,包括 6 个新的微卫星标记 (cam)、1 个插入位点多态性标记 (caISBP)、2 个单核苷酸多态性 (caSNP) 和 1 个基因特异性标记 (caIND)。利用这些新标记和之前发表的其他标记,通过代表 1742 条系的五个分离群体构建了该基因座的比较精细图谱。位于 ABC 转运蛋白基因内的 caSNP4 和位于该基因上游的 cam8 之间 4.9kb 间隔处的感病系发生重组,这进一步证明了该基因座的 ABC 转运蛋白是 Lr34,排除了四个相邻基因。最初,描述了 ABC 转运蛋白基因的三个突变形成两个单倍型。随后,在该基因的外显子 22 中描述了第三个突变组合和另一个罕见的突变。我们鉴定了外显子 10 中的另一个新突变,该突变会导致移码并可能失去功能。该突变仅在 Lr34-系中发现,构成了一个新的分子单倍型。对 700 个普通小麦种质资源系的两个种质资源集的特征描述,使我们能够了解迄今为止鉴定的 ABC 单倍型的频率及其在世界各地种质资源中的分布。除了之前描述的四个单倍型外,在两个来自种质资源集的 700 个系中发现了第五个单倍型。这些系表现出 indel11 缺失的特征,与 Lr34+系相同,但可能对叶锈病敏感。图谱和单倍型数据表明,在所描述的所有标记中,标记 caIND11 是 Lr34 辅助选择的最佳诊断标记,因为它是共显性的,稳健的,除了 2/700 个系外,它的诊断性很高。还描述了其他标记,为具有不同技术的实验室提供替代方案。