Using Next-Generation Sequencing Technologies to Map Wheat Leaf Rust Resistance Gene Lr16

Puccinia triticina causes significant yield losses worldwide. Lr16 is a wheat leaf rust resistance gene found in some varieties grown in the northern Great Plains of the U.S. that provides partial resistance at the seedling stage. The Lr16 gene is located at the tip of chromosome 2B, and the closest molecular markers have mapped between 1 and 9 cM depending on the population used. The objective of this research is to use RNA-Seq and genotyping by sequencing (GBS) technologies to develop new markers linked to Lr16. RNA was isolated from seedling Thatcher (Tc) and TcLr16 and used to generate cDNA. The cDNA was then fragmented, sequenced and reassembled back to Thatcher. Contigs from TcLr16 that did not align to Tc were analyzed using BLAST to identify putative gene functions. Primers were designed to target resistance gene analog sequences not found in Tc. PCR reactions were performed using these primers and previously known SSR markers on an F₂ CS x TcLr16 mapping population consisting of 192 plants. DNA from resistant and susceptible plants from this same mapping population was used for GBS to develop SNP markers. Progress on the mapping will be presented.