Huang Li, Brooks Steven A, Li Wanlong, Fellers John P, Trick Harold N, Gill Bikram S
Wheat Genetics Resource Center, Department of Plant Pathology, Kansas State University, Manhattan 66506-5502, USA.
Genetics. 2003 Jun;164(2):655-64. doi: 10.1093/genetics/164.2.655.
We report the map-based cloning of the leaf rust resistance gene Lr21, previously mapped to a gene-rich region at the distal end of chromosome arm 1DS of bread wheat (Triticum aestivum L.). Molecular cloning of Lr21 was facilitated by diploid/polyploid shuttle mapping strategy. Cloning of Lr21 was confirmed by genetic transformation and by a stably inherited resistance phenotype in transgenic plants. Lr21 spans 4318 bp and encodes a 1080-amino-acid protein containing a conserved nucleotide-binding site (NBS) domain, 13 imperfect leucine-rich repeats (LRRs), and a unique 151-amino-acid sequence missing from known NBS-LRR proteins at the N terminus. Fine-structure genetic analysis at the Lr21 locus detected a noncrossover (recombination without exchange of flanking markers) within a 1415-bp region resulting from either a gene conversion tract of at least 191 bp or a double crossover. The successful map-based cloning approach as demonstrated here now opens the door for cloning of many crop-specific agronomic traits located in the gene-rich regions of bread wheat.
我们报道了叶锈病抗性基因Lr21基于图谱的克隆，该基因先前被定位到普通小麦（Triticum aestivum L.）1DS染色体臂远端的一个基因丰富区域。二倍体/多倍体穿梭定位策略有助于Lr21的分子克隆。通过遗传转化和转基因植物中稳定遗传的抗性表型证实了Lr21的克隆。Lr21全长4318 bp，编码一个1080个氨基酸的蛋白质，该蛋白质包含一个保守的核苷酸结合位点（NBS）结构域、13个不完美的富含亮氨酸重复序列（LRR），以及一个在已知NBS-LRR蛋白N端缺失的独特的151个氨基酸序列。在Lr21基因座进行的精细结构遗传分析在一个1415 bp区域内检测到一个非交叉事件（侧翼标记未交换的重组），该事件由至少191 bp的基因转换片段或双交换导致。本文所展示的成功基于图谱克隆方法，为克隆位于普通小麦基因丰富区域的许多作物特异性农艺性状打开了大门。
