Molecular Characterization of Slow-Rusting Genes Lr34/Yr18 in Chinese Wheat Cultivars

Lr34 and Yr18 are important slow rusting resistance genes that have been widely used in many countries. The aim of this study was to identify Lr34/Yr18 genes in 231 Chinese wheat cultivars and 422 landraces using an STS marker csLV34, which can amplify a 150-bp and a 229-bp fragment in the genotypes with and without Lr34/Yr18, respectively. The results indicated that only 14 genotypes carried the resistance genes Lr34/Yr18 in the improved wheat cultivars, with a frequency of 6.1%. Different frequencies were found in wheat cultivars from different zones, which were 0, 3.0%, 21.4%, 16.7%, and 33.3% in North Plain Winter Wheat Region (NPWWR), Yellow-Huai Facultative Winter Wheat Region (YHFWWR), Middle-Lower Yangtze Valley Winter Wheat Region (MLYVWWR), Southwest Winter Wheat Region (SWWR), and Northwest Spring Wheat Region (NSWR), respectively. Whereas, 85.1% of 422 landraces contained Lr34/Yr18, with the frequencies of 89.6%, 77.4%, 93.1%, 93.8%, 96.6%, and 61.1% in NPWWR, YHFWWR, MLYVWWR, SWWR, Southern China Winter Wheat Region (SCWWR) and NSWR, re-spectively. The marker csLV34 exhibited a good repeatability, and can be therefore used for the identification of Lr34/Yr18 in wheat breeding programs.