|Kolmer, James - Jim|
Submitted to: Theoretical and Applied Genetics
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/15/2005
Publication Date: 8/1/2005
Citation: Zhang, W., Lukaszewski, A., Kolmer, J.A., Soria, M.A., Goyal, S., Dubcovsky, J. 2005. Molecular characterization of durum and common wheat recombinant lines carrying leaf rust resistance gene (Lr19) and yellow pigment (Y) genes from Lophopyrum ponticum. Theoretical and Applied Genetics. 111(3):573-582. Interpretive Summary: The wild relative of wheat know as Lophopyrum ponticum carries a gene called Lr19 which gives wheat resistance to the leaf rust disease caused by the fungus Puccinia triticina. The gene Lr19 is very close on the wheat chromosome to a gene that gives a very distinct yellow flour color. This study used molecular markers using biotechnology to determine the location of Lr19 and the yellow flour gene on the wheat chromosomes. The rust resistance gene and the yellow flour gene were transferred to durum wheat cultivars with the molecular markers to improve their rust resistance and pasta making qualities.
Technical Abstract: Chromosome 7E from Lophopyrum ponticum carries a valuable leaf rust resistant gene designated Lr19. This gene has not been widely used in common wheat breeding because of linkage with the yellow pigment gene Y. This gene tints flour yellow reducing its appeal in bread making. However, a high level of yellow pigment is desirable in durum wheat breeding. We produced 97 recombinant chromosomes between L. ponticum transfer 7D.7E#1 and its wheat homoeologues using the ph1b mutation that promotes homoeologous pairing. We characterized a subset of 37 of these lines with eleven molecular markers and evaluated their resistance to leaf rust and the abundance of yellow pigment. The Lr19 gene was mapped between loci Xwg420 and Xmwg2062, whereas Y was mapped distal to Xpsr687, the most distal marker on the long arm of chromosome 7. A short terminal 7EL segment translocated to 7A, including Lr19 and Y (line 1-23) has been transferred to durum wheat by backcrossing. The presence of this alien segment significantly increased the abundance of yellow pigment. Lr19 also conferred resistance to a new durum leaf rust race from California and Mexico that is virulent on most durum wheat cultivars. The new durum lines with the recombinant 7E segment will be useful parents to increase yellow pigment and leaf rust resistance in durum wheat breeding programs. For the common wheat breeding programs, we selected the recombinant line 1-96, which has an interstitial 7E segment carrying Lr19 but not Y. This recombinant line can be used to improve leaf rust resistance without affecting flour color. The 7EL/7DL 1-96 recombinant chromosome did not show the meiotic self elimination previously reported for a 7EL/7BL translocation.