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Tagging and Validation of a Major Quantitative Trait Locus for Leaf Rust Resistance and Leaf Tip Necrosis in Winter Wheat Cultivar Forno

October 2004 , Volume 94 , Number  10
Pages  1,036 - 1,041

T. Schnurbusch , E. Bossolini , M. Messmer , and B. Keller

First, second, and fourth authors: Institute of Plant Biology, University of Zürich, Zollikerstr. 107, CH-8008 Zürich, Switzerland; and third author: Pharmaceutical Institute, University of Basel, Benkenstr. 254, CH-4108 Witterswil, Switzerland

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Accepted for publication 8 June 2004.

A major leaf rust (Puccinia triticina) resistance quantitative trait locus (QTL) ( previously has been described on chromosome 7DS in the winter wheat (Triticum aestivum) cv. Forno. It was detected in a population of single-seed descent (SSD) lines derived from the cross Arina × Forno. conferred a durable and slow-rusting resistance phenotype, co-segregated with a QTL for leaf tip necrosis (LTN) and was mapped close to Xgwm295 at a very similar location as the adult plant leaf rust resistance gene Lr34 found in some spring wheat lines. Here, we describe the validation of this QTL by mapping it to the same chromosomal region close to Xgwm295 on chromosome 7DS in a population of SSD lines from the winter wheat × spelt (T. spelta) cross Forno × Oberkulmer. In both populations, the log of the likelihood ratio curves for leaf rust resistance and LTN peaked at identical or very similar locations, indicating that both traits are due to the same gene. We have improved the genetic map in the target region of using microsatellite and expressed sequence tag (EST) markers. Two EST loci (Xsfr.BF473324 and Xsfr.BE493812) define a genetic interval of 7.6 centimorgans containing, a considerably more precise genetic location for this QTL than previously described both in spring and winter wheat. The identified genetic interval is physically located in the distal 39% of chromosome 7DS. Single-marker analysis identified Xsfr.BF473324 and Xgwm1220 as the most informative loci for and In the rice genome, the two ESTs flanking the chromosomal segment in wheat are conserved on chromosome 6S in a region colinear with wheat chromosome 7DS. There, they define a physical region of three rice bacterial artificial chromosomes spanning ≈300 kb.

© 2004 The American Phytopathological Society