Characterization of Seed Rot Resistance to Pythium aphanidermatum in Soybean

Abstract

The soybean [Glycine max (L.) Moench.] cultivar ‘Archer’ has a single gene for resistance to hypocotyl infection by Pythium aphanidermatum (Rpa1) but it is not known if this source of resistance limits pre‐emergence damping‐off caused by this pathogen. Resistance in Archer to pre‐emergence damping‐off caused by P. aphanidermatum was characterized in 84 F2:6 soybean lines derived from a cross of ‘Archer’ (the resistant parent) and ‘Hutcheson’ (the susceptible parent). The lines and parents were evaluated for percent germination at 7 days and percent stand at 14 days via a seed plate assay and an infested vermiculite assay, respectively. The lines were assayed with 5403 single‐nucleotide polymorphism (SNP) markers and the results compared with the assay data. Seed germination and plant stands for the Archer × Hutcheson population fit the model for a quantitative trait indicating that Pythium resistance was controlled by multiple genes or quantitative trait loci (QTLs). Two QTLs were identified by each of the two phenotyping methods on chromosomes 4 and 7. The QTL on chromosome 4 explained 8.29 and 13.76 % of the variation and the QTL on chromosome 7 accounted for 4.5 and 13.85 % of the variation in the seed plate and infested vermiculite assays, respectively. Heritability of resistance was 0.8534 and 0.6955 in the seed plate and the infested vermiculite assays, respectively, indicating that Pythium resistance from Archer could successfully be incorporated into soybean breeding programs. These QTLs were not associated with Rpa1, the gene for resistance to hypocotyl symptoms.

Quantitative Disease Resistance Loci towards Phytophthora sojae and Three Species of Pythium in Six Soybean Nested Association Mapping Populations

“…A single R gene was mapped on chromosome 13 for resistance to Py. This was followed by mapping quantitative disease resistance loci (QDRL) on chromosomes 4 and 7 in Archer using seed plate assays and cup assays (Urrea et al, 2017). (Rosso et al, 2008) in the cultivar Archer (Cianzio et al, 1991).…”

“…Resistance towards P. sojae has been identified in numerous soybean genotypes; >25 single Rps genes as well as numerous quantitative trait loci (QTL) have been mapped (Dorrance and Schmitthenner, 2000;Wang et al, 2010Wang et al, , 2012bLee et al, 2014;Matthiesen et al, 2016;Schneider et al, 2016;Dorrance, 2018). Although resistance towards Pythium has been identified in several soybean genotypes (Griffin, 1990;Bates et al, 2008;Ellis et al, 2013;Balk, 2014), it has only been mapped towards three species of Pythium to date (Rosso et al, 2008;Ellis et al, 2013;Stasko et al, 2016;Urrea et al, 2017;Lin et al, 2018;Klepadlo et al, 2018). A single R gene was mapped on chromosome 13 for resistance to Py.…”

“…(Rosso et al, 2008) in the cultivar Archer (Cianzio et al, 1991). This was followed by mapping quantitative disease resistance loci (QDRL) on chromosomes 4 and 7 in Archer using seed plate assays and cup assays (Urrea et al, 2017). Resistance to Py.…”

Mapping Quantitative Trait Loci for Tolerance to Pythium irregulare in Soybean (Glycine max L.)

“…Two types of resistance have currently been discovered for resistance to Pythium spp. in soybean, including R-type of resistance (Rosso et al 2008), and quantitative resistance or tolerance ( Ellis et al , 2013 , Stasko et al , 2016 , Urrea et al , 2017 ). Using a similar hypocotyl inoculation assay and evaluation standards as for Phytophthora sojae ( Dorrance et al 2004 ), an R-type resistance gene, Rpa1 (for resistance to P. aphanidermatum-1 ), was dissected and mapped to MLG F (Chromosome 13) from a resistant soybean cultivar ‘Archer’ (Rosso et al 2008).…”

“…For Pythium disease resistance, although not commonly deployed, host resistance genes have been described to be an optimum option. ( Rupe et al 2011 , Nanayakkara et al , 2002, Ellis et al 2013 , Stasko et al 2016 , Urrea et al 2017 ).…”