Genetic Analysis of Adult Plant Resistance to Yellow Rust and Leaf Rust in Common Spring Wheat Quaiu 3

Abstract

Identifying and utilizing rust resistance genes in wheat has been hampered by the continuous and rapid emergence of new pathogen races. A major focus of many wheat breeding programs is achieving durable adult plant resistance (APR) to yellow (stripe) rust (YR) and leaf (brown) rust (LR), caused by Puccinia striiformis and P. triticina, respectively. This study aimed to determine the genetic basis of resistance to YR and LR in the common spring wheat ‘Quaiu 3’. To that end, we evaluated 198 F5 recombinant inbred lines (RILs), derived from a cross of susceptible ‘Avocet-YrA’ with Quaiu 3, for APR to LR and YR in artificially inoculated field trials conducted in Mexico during the 2009 and 2010 growing seasons. High narrow-sense heritability (h2) estimates, ranging between 0.91 and 0.95, were obtained for both LR and YR disease severities for both years. The quantitative and qualitative approaches used to estimate gene numbers showed that, in addition to known resistance genes, there are at least two to three APR genes associated with LR and YR resistance in the RIL population. The moderately effective race-specific resistance gene Lr42 and the pleiotropic slow-rusting APR gene Lr46/Yr29 were found to interact with additional unidentified APR genes. The unidentified APR genes should be of particular interest for further characterization through molecular mapping, and for utilization by wheat breeding programs.

Saturated Genetic Mapping of Wheat Streak Mosaic Virus Resistance Gene Wsm2 in Wheat

“…tritici); Lr27 (Mago et al, 2011) andLr74 (McIntosh et al, 2016) for resistance to leaf rust (Puccinia triticina f. sp. tritici); and Yr30 (Singh et al, 2000;Suenaga et al, 2003;Basnet et al, 2013) and Yr58 (McIntosh et al, 2016) for resistance to stripe rust (Puccinia striiformis). It will be important to study the interaction of Wsm2 with other genes to elucidate more about the mechanism of resistance to WSMV and determine if there is an overlap of genes for different traits.…”

Advanced Breeding Strategies to Mitigate the Threat of Yellow Stripe Rust of Wheat

“…Additional Avocet-Yr A-derived minor QTL were also detected for YR on chromosomes 1A, 3D, 4A, and 6A. Yr54 is a newly characterized APR gene which can be combined with other genes by using closely linked molecular markers (Basnet et al, 2013).…”

“…Similarly, during the last 15 years, several molecular mapping studies have reported dozens of quantitative trait loci (QTL) distributed throughout all 21 chromosomes for YR resistance, and at least in 20 chromosomes for LR resistance in hexaploid wheat germplasm (Naz et al, 2008;Basnet 2012;Singh 2012 http://wheatatlas.cimmyt.org/country/varieties/ AFG/0). Quaiu 3 does not seem to carry any effective seedling resistance genes for YR resistance, as it displays high infection type (IT) ratings in seedling screenings (IT 6-8 on the 0-9 scale, depending on Mexican P. striiformis races and the greenhouse environment).…”

“…Quaiu 3 does not seem to carry any effective seedling resistance genes for YR resistance, as it displays high infection type (IT) ratings in seedling screenings (IT 6-8 on the 0-9 scale, depending on Mexican P. striiformis races and the greenhouse environment). However, it carries a moderately effective race-specific LR resistance gene (Lr42), initially transferred from Aegilops tauschii to the winter wheat line KS91WGRC11 (Basnet et al, 2013). In a previous study, Basnet et al, (2013) also estimated a minimum of three genes conferring resistance to both LR and YR in Quaiu 3.…”

“…However, it carries a moderately effective race-specific LR resistance gene (Lr42), initially transferred from Aegilops tauschii to the winter wheat line KS91WGRC11 (Basnet et al, 2013). In a previous study, Basnet et al, (2013) also estimated a minimum of three genes conferring resistance to both LR and YR in Quaiu 3. In addition to Lr42, they also suggested that Quiau 3 carries two APR genes, Yr29 and Yr30, based on closely linked molecular markers.…”