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Southern stem canker (SSC) in soybean [Glycine max (L.) Merrill], caused by the fungal pathogen Diaporthe aspalathi, is a major disease in the southern United States. It can cause up to 80% yield loss in severely infected fields. Plant introduction (PI) 398469, a Maturity Group VI soybean accession from South Korea, is one of six known sources of resistance to SSC. To determine the genetics of the resistance provided by PI 398469, F2:3 and F5‐derived recombinant inbred line (RIL) populations were developed from a cross with the susceptible breeding line G81‐2057. Both populations were phenotyped in the greenhouse using a modified toothpick method. The SSC‐resistant and susceptible DNA bulks consisting of 20 resistant and 18 susceptible families were created from the F2:3 population and genotyped using the Infinium SoySNP50K BeadChips for a bulked segregant analysis (BSA). Based on BSA results, 22 Kompetitive allele specific polymerase chain reaction (KASP) markers were designed to genotype the RIL population. Quantitative trait locus (QTL) analysis identified qRdm_14, on chromosome (Chr) 14 with an R2 of 62%. Linkage mapping in the F2:3 population confirmed the presence of a QTL on Chr 14. F5‐derived RILs derived from G81‐2057 × Crockett were phenotyped for SSC resistance and genotyped with the KASP markers to examine the relationship between Rdm3 from Crockett and qRdm_14 from PI 398469. Both PI 398469 and Crockett carried realleles at the Rdm3 locus for resistance to SSC. The QTL and KASP marker information could be used to screen breeding lines for resistance to SSC. Core Ideas: Resistance to soybean southern stem canker is provided by a major QTL on chromosome 14 from PI 398469.Both PI 398469 and Crockett carry resistance alleles at the Rdm3 locus on chromosome 14 for SSC resistance.KASP markers developed for the Rdm3 locus can be used by breeders to perform marker‐assisted selection. [ABSTRACT FROM AUTHOR]

G11‐7013 (Reg. no. GP‐447, PI 699240) is a conventional maturity group (MG) VII soybean [Glycine max (L.) Merr.] line. It contains a 50% genetic background of an accession from South Africa by pedigree, with resistance to soybean cyst nematode race 3 (Heterodera glycines), southern root‐knot nematode (Meloidogyne incognita), and stem canker (Diaporthe aspalathi) and high meal protein. G11‐7013 was developed and released by the University of Georgia (UGA) Agricultural Experiment Stations in 2020. G11‐7013 is an F5–derived plant selection from 'Boggs' × PI 221717. G11‐7013 consistently yielded more than the elite parent Boggs in UGA advanced yield trials. Across 25 environments in the United Soybean Board Southern Protein Diversity Yield Trials MG‐VII, G11‐7013 yielded a range of 93–104% of the elite check cultivar mean over 5 yr, with an average of 98% of check means. G11‐7013 has a protein content of 436 g kg–1, a meal protein value of 51%, and an oil content of 217 g kg–1. G11‐7013 exceeds the desired meal protein levels required for soybean and derives from a diverse genetic background. Because of its high yield, high protein content, disease resistance package, and diverse pedigree, G11‐7013 can be used as a parental stock in both public and private sectors to develop high‐yielding, high‐meal‐protein soybean cultivars. [ABSTRACT FROM AUTHOR]

Plant-parasitic nematode species are one of the greatest threats to cause serious yield loss throughout soybean production regions of the United States. Soybean [Glycine max (L.) Merr.] cultivars of different maturity groups carry known resistance to soybean cyst nematode (Heterodera glycines, SCN) at rgh1 and Rhg4 loci. Continuous use of these genes caused SCN population shifts and overcoming host resistance over time. Lack of genetic diversity created a bottleneck in development of new cultivars containing novel SCN resistance genes. Additional sources of resistance to southern root-knot nematode (Meloidogyne incognita, SRKN) and reniform nematode (Rotylenchlus reniformis, RN) could result in supplemental protection of soybean yield. This research focused on determining known and new sources of SCN resistance in 1220 soybean accessions divided into two groups: (i) early-maturity groups (000-II) screened with two SCN populations, and (ii) medium-maturity groups (III-V) screened with six SCN populations. Based on the initial screening results, a subset of 76 accessions was selected for further phenotyping with SCN, SRKN, and RN populations and supplemented by genotyping using molecular markers. The results revealed that 56 lines were resistant to two nematode species in various combinations, and 12 lines were resistant to all three nematode species. Moreover, potential new sources of resistancecarrying genes other than rhg1 and Rhg4 loci were pinpointed. Interestingly, RN resistance highly correlated with rhg1 locus suggesting a common gene or tight linkage. Identified resistant soybean accessions provide promising materials for discovery of novel genes to support cultivar development. [ABSTRACT FROM AUTHOR]

Typical soybean oil is composed of palmitic, stearic, oleic, linoleic and linolenic acids. High oleic acid content in soybean seed is a key compositional trait that improves oxidative stability and increases oil functionality and shelf life. Using a marker-assisted selection method, near-isogenic lines ( NILs) of G00-3213 for the high oleic trait were developed and yield tested. These NILs have various combinations of FAD2-1A and FAD2-1B alleles that were derived from the same backcrossing populations. The results indicated that G00-3213 NILs with both homozygous mutant FAD2-1A and FAD2-1B alleles produced an average of 788 g/kg oleic acid content. The results also demonstrated that possessing these mutant alleles did not cause a yield reduction. Furthermore, seed germination tests across 12 temperatures (12.8-32.0°C) showed that modified seed composition for oleic acid in general did not have a major impact on seed germination. However, there was a possible reduction in seed germination vigour when high oleic seeds are planted in cold soil. The mutant FAD2-1A and FAD2-1B alleles did not hinder either seed or plant development. [ABSTRACT FROM AUTHOR]