Soluble sugar is an important quality trait in food‐grade soybeans [Glycine max (L.) Merr.]. Desirable sugars such as sucrose, glucose, and fructose can help improve the taste and flavor of soyfood including tofu, soymilk, and natto; whereas oligosaccharides including raffinose and stachyose are indigestible by humans and animals and often cause flatulence or diarrhea. In this study, 241 plant introductions (PIs) of three maturity groups (MGs) from 28 origins were investigated for seed sugar content including glucose, fructose, sucrose, raffinose, and stachyose. Variation was detected in individual and total sugars in soybean PIs from different origins and MGs. Sucrose and stachyose are the major sugars in soybean seed. The sucrose content ranged from 1.6 to 95.4 mg g−1 with 13 PIs containing greater than 70 mg g−1 and 14 PIs having less than 10 mg g−1 The stachyose content ranged from 0.2 to 69.6 mg g−1 with 14 PIs containing less than 10 mg g−1 stachyose. The high sucrose and low stachyose types are the most valuable for breeding specialty soybeans for soyfood and animal feed. In addition, 30 PIs were identified as having high concentrations of glucose or fructose as major sugars. This new class of high glucose or fructose has not been reported before. While soybean germplasm with unique sugar profiles may be useful for future breeding and genetic research, environmental effects on sugar stability will need to be further investigated.

Fusarium graminearum, a pathogen of wheat and corn, was reported recently as a saprophytic fungus colonizing soybean (Glycine max L. Merr.) fruits and seeds at R7 in Argentina (2). To evaluate the capacity of F. graminearum obtained from stem and seeds of symptomatic soybean plants that cause disease on soybean seedlings, isolates were obtained during the 2001 to 2002 growing season from: (i) the basal one-third of stems from field-grown soybean plants, collected at R5, with light brown external and internal discoloration and leaves with interveinal chlorosis; and (ii) soybean seeds with pink tegument. The pathogen was isolated on potato glucose agar acidified with 0.2% lactic acid (PGAA). Isolates were identified as F. graminearum on the basis of growth rate and pigmentation of colonies on PGAA, lack of microconidia (1), and morphology and size of typical macroconidia in sporodochia developed on Spezieller Nährstoffarmer Agar (3). Isolates of F. graminearum, CE135 and CE136 (from wheat) and CE137 (from corn) deposited in the Centro de Referencia en Micología (CEREMIC), Fac. Farmacia y Bioquímica, UNR, Argentina, were used as references in identifying the soybean isolates. Plants (14-day-old) were inoculated separately with stem and seed isolates in the greenhouse at 26 ± 2 and 20 ± 2°C day/night temperature by inserting a piece of mycelium into a wound made with a scalpel in the hypocotyl. A completely randomized block design (RCB) was utilized with four replicate pots with four plants per pot. Plants wounded but without mycelium served as controls. This test was conducted twice (experiments 1 and 2). Another test was completed by burying a thin layer of wheat caryopsis colonized by fungal mycelium of the stem isolate CE170 in the soil of pots. Plants in pots with soil without inoculum served as controls (4). The experiment was conducted twice (experiments 3 and 4) in an RCB with five replications, four plants per replication. The progress of symptoms in experiments 1 and 2 were stem with light brown discoloration around the inoculation point that extended progressively along the stem, interveinal chlorosis or loss of turgence of unifoliate leaves, and interveinal chlorosis of trifoliate leaves followed by plant wilting and death. Twenty-one days after inoculation, average percentages of dead plants (%DP) was 42 and 21% for stem and seed isolates, respectively. For experiments 3 and 4, %DP was 56%, 45 days after emergence. These plants had roots with light brown, necrotic areas. Control plants remained healthy. The pathogen was reisolated from the stem (100%) and root (57%) tissues of symptomatic plants but not from similar tissues of control plants. To our knowledge, this is the first report of a pathogenic relationship between F. graminearum and soybean. References: (1) P. E. Nelson et al. Fusarium species: An Illustrated Manual for Identification. The Pennsylvania State University Press, University Park, PA, 1983. (2) R.N. Pioli et al. Fitopatología 35(2):111, 2000. (3) B. A. Summerell et al. Plant Dis. 87:117, 2003. (4) C. E. Windels. Fusarium. Pages 115–128 in: Methods for Research on Soilborne Phytopathogenic Fungi. L. L. Singleton, J. D. Mihail, and C. M. Rush, eds. The American Phytopathological Society, St. Paul, MN, 1992.

Pythium damping‐off and root rot of soybean [Glycine max (L.) Merr.] causes poor stands and consequently reduces yields. Resistance to seedling diseases caused by Pythium spp. was reported in the soybean cultivar Archer and was described to be associated with the Rps1k gene for resistance to Phytophthora sojae. To characterize the inheritance of Pythium damping‐off resistance in Archer and to determine if this resistance is linked to Rps1k, the cross of Archer × ‘Hutcheson’ (susceptible parent) was made and F2:4 lines generated. Parents and F2:4 lines were screened with Pythium aphanidermatum using a hypocotyl inoculation technique. Five days after inoculation, plant survival was scored. The F2:4 lines and parents were also inoculated with race 7 of P. sojae to assess the association of resistance to Pythium spp. with the Rps1k gene. Data from the F2:4 lines fit the model for a single dominant gene in Archer that confers resistance to P. aphanidermatum. The genetic linkage test showed that resistance to P. aphanidermatum was independent of the Rps1k gene in Archer. To identify the genomic location of the Pythium resistance gene, F2:4 lines were screened with simple sequence repeat (SSR) markers from all the soybean molecular linkage groups (MLGs). Two SSR markers, Satt510 and Satt114 on MLG F, which were polymorphic between the parents and the resistant and susceptible bulks, were shown to be associated with Pythium resistance. The Pythium resistance gene, named Rpa1, was located 10.6 cM from Satt510 and 26.6 cM from Satt114.

‘Osage’ soybean [Glycine max (L.) Merr.] (Reg. No. CV‐495, PI 648270) was developed and released by the Arkansas Agricultural Experiment Station as a Maturity Group V conventional cultivar in March 2007. It was derived from the cross ‘Hartz 5545’ × ‘KS4895’ and has been evaluated in 130 field tests in several southern states. Osage is widely adapted to areas between 33 and 37°N latitude and has high yield potential and moderately high protein content. Overall, when grown in southern environments, Osage had seed yield 3.2% greater than the check ‘5601T’ and 3.3% greater than the check ‘5002T’. Seed protein of Osage is 3.1% and 5.4% greater than 5601T and 5002T, respectively. Osage is resistant to several important diseases in the Mid‐South USA, including southern stem canker, sudden death syndrome, soybean mosaic virus, and frogeye leaf spot.

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