A Cryptic Wheat-Aegilops triuncialis Translocation with Leaf Rust Resistance Gene Lr58.
Vasu Kuraparthy1, Shilpa Sood1, Parveen Chunneja2, Harcharan S. Dhaliwal3, Satinder Kaur2, Robert L. Bowden4, and Bikram S. Gill1. (1) Kansas State University, Department of Plant Pathology, Manhattan, KS 66502-5502, (2) Punjab Agricultural University, Department of Plant Breeding, Genetics & Biotechnology, Ludhiana, 141004, India, (3) Indian Institute of Technology, (3) Department of Biotechnology, Roorkee, 247667, India, (4) USDA-ARS, Kansas State University, Plant Science and Entomology Research Unit, Manhattan, KS 66502-5502
Genes transferred to crop plants from wild species are often associated with deleterious traits. Using molecular markers, we detected a cryptic introgression with a leaf rust resistance gene transferred from Aegilops triuncialis L. into common wheat (Triticum aestivum L.). One agronomically desirable rust resistant introgression line was selected and advanced to BC3F11 from a cross of hexaploid wheat and Ae. triuncialis. In situ hybridization using Ae. triuncialis genomic DNA as a probe failed to detect the alien introgression. The translocation line was resistant to the most prevalent races of leaf rust in India and Kansas. Genetic mapping in a segregating F2:3 population showed that the rust resistance was monogenically inherited. Homoeologous group-2 RFLP markers XksuF11, XksuH16, and Xbg123 showed diagnostically polymorphic alleles between the resistant and susceptible bulks. The alien transfer originated from homoeologous chromosome recombination. The Ae. triuncialis-specific alleles of XksuH16, XksuF11, Xbg123 and one SSR marker Xcfd50 co-segregated with the rust resistance suggesting that the wheat-Ae. triuncialis translocation occurred in the distal region of chromosome arm 2BL. This translocation was designated T2BS·2BL-2tL(0.95). The unique source and map location of the introgression on chromosome 2B indicated that the leaf rust resistance gene is new and was designated Lr58