Novel sources of leaf rust resistance in winter wheat

Authors: LI, GENQIAO - Oklahoma State University; Xu, Xiangyang; Bai, Guihua; CARVER, BRETT - Oklahoma State University; HUNGER, ROBERT - Oklahoma State University; Bonman, John

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/21/2016
Publication Date: 3/3/2017
Citation: Li, G., Xu, X., Bai, G., Carver, B.F., Hunger, R.M., Bonman, J.M. 2017. Novel sources of leaf rust resistance in winter wheat. Crop Science. 57(2):865-876.

Interpretive Summary: Leaf rust is one of the most widespread and destructive diseases of wheat. Most newly developed wheat cultivars or breeding lines in the southern Great Plains of the USA are susceptible to Pt2013, a bulk of Puccinia triticina (Pt) races collected from multiple fields in Oklahoma, indicating the urgency of finding new resistance sources. We screened a set of 2171 landraces and historical cultivars using three Pt pathotypes, and identified 25 accessions exhibiting high resistance to all three pathotypes. Another 66 and 53 accessions showed high resistance to one and two pathotypes, respectively. These resistant landraces and historical cultivars are valuable for breeding leaf rust resistance, and can be directly used in wheat breeding.

Technical Abstract: Leaf rust is one of the most widespread diseases of wheat, causing significant yield losses. More than 70 leaf rust resistance genes have been reported, but most of them have lost their effectiveness in the southern Great Plains of the USA. Thus continuous search for new sources of resistance is essential to the improvement of wheat production in this region. In this study, we evaluated leaf rust resistance of newly released wheat breeding lines and a worldwide collection of landraces and historical cultivars to identify novel resistance sources. Results showed that only four out of 183 cultivars and breeding lines recently developed in the U.S. hard red winter wheat breeding programs (2.2%) were highly resistant to Pt2013, a bulk of Puccinia triticina (Pt) races collected from multiple fields in Oklahoma, indicating the urgency of finding new resistance genes. Among 2171 accessions screened with Pt2013, 26 landraces and 61 historical cultivars exhibited high resistance, and 159 landraces and 309 historical cultivars showed moderate resistance. These highly or moderately resistant accessions were further evaluated for their responses to another two Pt races that dominated in the fields of Oklahoma in 2015, Pt52-2 and Pt54-1, and 25 of them showed high resistance to these two races and the bulk of races. Another 66 and 53 accessions showed high resistance to one and two races, respectively. Genetic diversity analysis based on 5011 single nucleotide polymorphism (SNP) markers identified several genetically duplicated or similar accessions. The resistance sources identified in this study are valuable for breeding leaf rust resistance.