Li J, Klindworth D L, Shireen F, Cai X, Hu J, Xu S S
Department of Plant Sciences, North Dakota State University, Fargo, ND 58105, USA.
Genome. 2006 Dec;49(12):1545-54. doi: 10.1139/g06-114.
The aneuploid stocks of durum wheat (Triticum turgidum L. subsp. durum (Desf.) Husnot) and common wheat (T. aestivum L.) have been developed mainly in 'Langdon' (LDN) and 'Chinese Spring' (CS) cultivars, respectively. The LDN-CS D-genome chromosome disomic substitution (LDN-DS) lines, where a pair of CS D-genome chromosomes substitute for a corresponding homoeologous A- or B-genome chromosome pair of LDN, have been widely used to determine the chromosomal locations of genes in tetraploid wheat. The LDN-DS lines were originally developed by crossing CS nulli-tetrasomics with LDN, followed by 6 backcrosses with LDN. They have subsequently been improved with 5 additional backcrosses with LDN. The objectives of this study were to characterize a set of the 14 most recent LDN-DS lines and to develop chromosome-specific markers, using the newly developed TRAP (target region amplification polymorphism)-marker technique. A total of 307 polymorphic DNA fragments were amplified from LDN and CS, and 302 of them were assigned to individual chromosomes. Most of the markers (95.5%) were present on a single chromosome as chromosome-specific markers, but 4.5% of the markers mapped to 2 or more chromosomes. The number of markers per chromosome varied, from a low of 10 (chromosomes 1A and 6D) to a high of 24 (chromosome 3A). There was an average of 16.6, 16.6, and 15.9 markers per chromosome assigned to the A-, B-, and D-genome chromosomes, respectively, suggesting that TRAP markers were detected at a nearly equal frequency on the 3 genomes. A comparison of the source of the expressed sequence tags (ESTs), used to derive the fixed primers, with the chromosomal location of markers revealed that 15.5% of the TRAP markers were located on the same chromosomes as the ESTs used to generate the fixed primers. A fixed primer designed from an EST mapped on a chromosome or a homoeologous group amplified at least 1 fragment specific to that chromosome or group, suggesting that the fixed primers might generate markers from target regions. TRAP-marker analysis verified the retention of at least 13 pairs of A- or B-genome chromosomes from LDN and 1 pair of D-genome chromosomes from CS in each of the LDN-DS lines. The chromosome-specific markers developed in this study provide an identity for each of the chromosomes, and they will facilitate molecular and genetic characterization of the individual chromosomes, including genetic mapping and gene identification.
硬粒小麦（Triticum turgidum L. subsp. durum (Desf.) Husnot）和普通小麦（T. aestivum L.）的非整倍体系主要分别在‘Langdon’（LDN）和‘中国春’（CS）品种中培育而成。LDN-CS D基因组染色体二体代换（LDN-DS）系，即一对CS D基因组染色体替代LDN相应的同源A或B基因组染色体对，已被广泛用于确定四倍体小麦中基因的染色体位置。LDN-DS系最初是通过将CS缺体-四体与LDN杂交，随后与LDN进行6次回交而培育出来的。随后又与LDN进行了5次额外回交对其进行改良。本研究的目的是利用新开发的TRAP（靶区域扩增多态性）标记技术，对一组最新的14个LDN-DS系进行特征分析，并开发染色体特异性标记。从LDN和CS中共扩增出307个多态性DNA片段，其中302个被定位到各个染色体上。大多数标记（95.5%）作为染色体特异性标记存在于单一染色体上，但4.5%的标记定位到2条或更多条染色体上。每个染色体上的标记数量各不相同，从低至10个（1A和6D染色体）到高至24个（3A染色体）。分别分配到A、B和D基因组染色体上的每个染色体平均有16.6、16.6和15.9个标记，这表明在3个基因组上检测到TRAP标记的频率几乎相等。将用于推导固定引物的表达序列标签（EST）来源与标记的染色体位置进行比较，发现15.5%的TRAP标记位于与用于生成固定引物的EST相同的染色体上。从定位在一条染色体或一个同源群上的EST设计的固定引物扩增出至少1个该染色体或群特异性的片段，这表明固定引物可能从靶区域产生标记。TRAP标记分析证实了每个LDN-DS系中至少保留了来自LDN的13对A或B基因组染色体以及来自CS的1对D基因组染色体。本研究中开发的染色体特异性标记为每个染色体提供了标识，它们将有助于对各个染色体进行分子和遗传特征分析，包括遗传作图和基因鉴定。
