Evaluation of Major Ancestors of North American Soybean Cultivars for Resistance to Three Pythium Species that Cause Seedling Blight

Abstract

Pythium seedling blight, which can be caused by a number of Pythium spp., is a disease that affects soybean (Glycine max) in the United States and Canada. Pythium ultimum var. ultimum, one of the most common pathogenic species, is favored by cool, wet conditions in early spring and causes seed decay, root rot, and seedling damping-off. In all, 102 major ancestors of modern North American cultivars and "first progeny" cultivars developed directly from ancestral lines were evaluated for resistance to P. ultimum var. ultimum and two other species of Pythium in greenhouse assays. Several ancestors and first progeny cultivars, as well as the resistant check Archer, had varying levels of partial resistance to an Illinois isolate of P. ultimum var. ultimum. In a subsequent experiment, four of the most resistant lines (PI 84637, Maple Isle, Fiskeby III, and Fiskeby 840-7-3) and the susceptible cultivar Kanro were screened for resistance against isolates of P. irregulare and P. sylvaticum, and resistance to P. ultimum var. ultimum was confirmed. The lines that were partially resistant to P. ultimum var. ultimum in the first experiment were also partially resistant to P. irregulare and P. sylvaticum. The P. ultimum var. ultimum isolate was the most aggressive of the three isolates, followed by the P. irregulare and P. sylvaticum isolates. Modern cultivars descended from the soybean lines with partial resistance to these pathogens could be useful sources of resistance to Pythium seedling blight if they are found to have similar levels of resistance.

Identification of Quantitative Disease Resistance Loci Toward Four Pythium Species in Soybean

“…Several studies have measured resistance toward different Pythium species (Rod et al, 2018;Lerch-Olson et al, 2020) and have identified QDRL, mostly minor, in RIL populations of soybean (Ellis et al, 2013;Stasko et al, 2016;Urrea et al, 2017;Klepadlo et al, 2019;Lin et al, 2018Lin et al, , 2020Scott et al, 2019). Almost all of the studies have shown partial resistance aside from one study by Rosso et al (2008) showing monogenic resistance.…”

“…Recently, several quantitative disease resistance loci (QDRL) for resistance to P. irregulare (Ellis et al, 2013;Stasko et al, 2016;Lin et al, 2018;Scott et al, 2019), P. aphanidermatum (Urrea et al, 2017), P. ultimum var sporangiiferum (Scott et al, 2019), P. sylvaticum (Lin et al, 2020), and P. ultimum var. ultimum (Rod et al, 2018;Klepadlo et al, 2019;Scott et al, 2019) have been identified using biparental soybean populations. Overall, only minor QDRL have been identified and have explained 4.5-17.8% of the phenotypic variation and are located on most chromosomes within the soybean genome.…”

Identifying sources of resistance in chickpea to seed rot and seedling damping‐off caused by metalaxyl‐resistant Pythium ultimum

“…This approach has been widely used to evaluate resistance to Pythium spp. in diverse grain legumes, including common bean (Campa, Perez‐Vega, Pascual, & Ferreira, 2010), soybean (Rod, Walker, & Bradley, 2018; Urrea, Rupe, Chen, & Rothrock, 2017), and chickpea (Kaiser & Hannan, 1983).…”

“…resistance to Pythium spp. in diverse grain legumes, including common bean (Campa, Perez-Vega, Pascual, & Ferreira, 2010), soybean (Rod, Walker, & Bradley, 2018;Urrea, Rupe, Chen, & Rothrock, 2017), and chickpea (Kaiser & Hannan, 1983). The majority of resistant accessions identified in the USDA-NPGS and ICRISAT mini-core collections were desi type, which typically produce smaller seeds than kabuli types (Toker, 2009).…”

Mining Fiskeby III and Mandarin (Ottawa) Expression Profiles to Understand Iron Stress Tolerant Responses in Soybean

“…Fiskeby III is reported to be more tolerant to a variety of abiotic stresses than most soybean germplasm [24][25][26][27][28]. Two studies have shown Fiskeby III to be tolerant to, though not completely resistant, to FeD stress.…”