The spring wheat (Triticum aestivum) cultivar Lemhi has one gene, and cultivars Lee, Compair, and Fielder have two genes each for resistance to stripe rust, caused by Puccinia striiformis. To determine the chromosomal locations of the genes, the cultivars were crossed with susceptible disomic Chinese Spring and a set of 21 Chinese Spring aneuploids. Monosomic F 1 plants were cytologically determined, grown in a green-house, and self pollinated to produce F 2 seed. F 2 seedlings and their parents were inoculated with selected North American races of P. striiformis. The results confirmed that Yr6 in Fielder is on chromosome 7B and Yr8 in Compair is on chromosome 2D; and they show that YrLem in Lemhi is on chromosome IB, YrLel in Lee is on chromosome 4D, YrLe2 in Lee is on chromosome 6D, YrCom in Compair is on chromosome 5B, and YrFie in Fielder is on chromosome 6D. None of the Lee genes that we detected with North American races is Yr7. We propose official gene designations Yr19 for YrCom, Yr20 for YrFie, Yr21 for YrLem. Yr22 for YrLel, and Yr23 for YrLe2
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Xianzhong Chen (1995) studied this question.