CHROMOSOME LOCATION OF LEAF RUST RESISTANCE GENE LR43 FROM AEGILOPS TAUSCHII IN COMMON WHEAT

Wheat leaf rust resistance gene Lr43 was recently transferred from Aeg ilops tauschii Coss. to common wheat (Triticum aestivum L.) to produce hard red winter wheat germplasm line KS92WGRC16. Monosomic and teloce ntric analyses were used to determine the chromosomal and chromosome a rm location of Lr43. KS92WGRC16 was crossed with each of the seven D-g enome monosomic lines. The F-2 families were inoculated with race PBJL of the leaf rust fungus, Puccinia recondita Roberge ex Desmaz. f. sp. tritici (Eriks. & E. Henn.) D.M. Henderson. The number of resistant t o susceptible seedlings did not deviate significantly from a 3:1 ratio in crosses involving 1D, 2D, 3D, 4D, 5D, or 6D monosomic lines. Howev er, the 7D monosomic-derived F-2 deviated significantly from a 3:1 rat io (chi(2) = 32.5 P < 0.001) indicating that Lr43 is located on this C hromosome. Twenty resistant F-2 plants from the critical cross were pr ogeny tested, and results confirmed the location of Lr43 on chromosome 7D. Telocentric analysis showed that Lr43 is on the short arm of chro mosome 7D (7DS) and it is unlinked to the centromere. This information may facilitate development of molecular markers and result in more ef ficient breeding for resistant cultivars.