Mapping of Stem‐Rust Genes <i>Sr9</i> and <i>Srl6</i> of Wheat¹

Abstract

The stem‐rust genes Sr9a from Red Egyptian and Srl6 from Thatcher, previously known to be located on chromosome 2B with little or no linkage between them, were mapped by means of telocentric chromosomes. Both genes lie on the long arm, and they showed 10.6% and approximately 50% crossing‐over, respectively, with the centromere. Male transmission of telocentric 2B L in competition with the entire 2B from Red Egyptian and Thatcher was 23.6% and 16.0%, respectively, as compared with only 0.4% and 4.1% for telo‐2Bs.