<p>Online Resource 1</p><p>Article title: “A QTL with major effect on reducing leaf rust severity on the short arm of chromosome 1A of wheat detected across different genetic backgrounds and diverse environments”</p><p>Journal: Theoretical and Applied Genetics</p><p>Authors: Ziyi Du, Mingzhe Che, Guohui Li, Jiang Chen, Wei Quan, Yan Guo, Zhen Wang, Junda Ren, Huyan Zhang, Zhongjun Zhang</p><p>Name, affiliation, and email of corresponding author: Zhongjun Zhang Department of Plant Pathology, China Agricultural University [email protected]</p><p>Identification of P. triticina races </p><p>Leaves bearing P. triticina uredinia were collected from the MX plants in the field plots of Gansu and Shandong during 2012 to 2014. Sixty single uredinial isolates (30 each location) derived from the collections were analyzed in 2014 following Long et al. (2002). Briefly, a collection consisted of one uredinia- bearing leaf. The leaves were air-dried and stored at 4℃ until analysis. Urediniospores from each collection were used to inoculate 7-day-old seedlings of the wheat cultivar Thatcher (CI 10003) grown in 10-cm-diameter pots. The inoculated seedlings were incubated in a dew chamber (100% relative humidity) at 18±1℃ overnight (18 hr). Then, the incubated seedlings were moved to a greenhouse and placed inside plexiglass chambers designed to keep the collections isolated from one another, with one chamber for each collection. The greenhouse was operated at temperatures between 18 and 28°C daily under natural light supplemented to 16 hr. After 12 to 15 days, three seedlings were saved per collection, each with the primary leaf trimmed to bear a single uredinium. Six to nine days later, urediniospores were collected separately from one such uredinium per collection. The isolates were increased through one uredinial generation on Thatcher seedlings. The urediniospores suspended in water containing 0.03% Tween 20 were atomized onto 7- to 8-day-old plants (five to seven plants) of each differential host. The differential series consisted of 16 near-isogenic lines of Thatcher with respective single resistance genes Lr1, Lr2a, Lr2c, Lr3, Lr3ka, Lr9, Lr10, Lr11, Lr14a, Lr16, Lr17, Lr18, Lr24, Lr26, Lr30, and LrB (Long et al. 2002). These lines, originally kindly provided by the USDA-ARS Cereal Disease Laboratory, University of Minnesota, St Paul, MN, USA, are maintained at the Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, and the Department of Plant Pathology, Hebei Agricultural University, Baoding 071001, P. R. China. The inoculated seedlings were incubated in dew chambers (100% relative humidity) at 18±1℃ overnight (18 hr), and then maintained at 18 to 28℃ daily in a 16-hr photoperiod. After 10 to 12 days, infection type (IT) was recorded as either high (IT 3 to 4) or low (IT 0 to 2+) folowing Long et al. (2002). Races were designated following the three letter code system of Long and Kolmer (1989), with an additional fourth letter that described the high or low infection type to Thatcher wheat lines with genes LrB, Lr10, Lr14a, and Lr18. </p>