THE INHERITANCE OF STEM RUST AND LEAF RUST RESISTANCE IN SOME ETHIOPIAN WHEAT COLLECTIONS

Common and durum wheat populations obtained from Sweden and originally collected in Ethiopia were screened for resistance to stem rust and l eaf rust. Resistant selections of common wheat were crossed and backcr ossed with either stem rust susceptible RL6071, or leaf rust susceptib le Thatcher. Genetic studies, based largely on tests of backcross F-2 families, showed that four of the selections had in common a recessive gene SrA. Plants with this gene were resistant (1(+) infection type) to all stem rust races tested. This gene was neither Sr26 nor Sr29. Th e resistance of other selections, based on tests with an array of rust isolates, was due to various combinations of Sr6, 8a, 9a, 9d, 9e, 11, 13, 30, and 36. One of the selections had linked genes, Lr19/Sr25. An other selection had a dominant gene for resistance (;1 infection type) to all the races of leaf rust. With the possible exception of this ge ne for leaf rust resistance and SrA, no obviously new resistance was f ound.