Alfalfa (Medicago sativa L.) flavonoids. 1. Apigenin and luteolin glycosides from aerial parts.

Nine flavones and adenosine have been identified in aerial parts of alfalfa, and their structures were established by spectral (FABMS and NMR) techniques. Five of the identified compounds, including apigenin 7-O-[beta-D-glucuronopyranosyl(1-->2)-O-beta-D-glucuronopyranosyl]-4'-O-beta-D-glucuronopyranoside, apigenin 7-O-[2-O-feruloyl-beta-D-glucuronopyranosyl(1-->2)-O-beta-D-glucuronopyranosyl]-4'-O-beta-D-glucuronopyranoside, apigenin 7-O-[2-O-feruloyl-[beta-D-glucuronopyranosyl(1-->3)]-O-beta-D-glucuronopyranosyl(1-->2)-O-beta-D-glucuronopyranoside], apigenin 7-O-[2-O-p-coumaroyl-[beta-D-glucuronopyranosyl(1-->3)]-O-beta-D-glucuronopyranosyl(1-->2)-O-beta-D-glucuronopyranoside], and luteolin 7-O-[2-O-feruloyl-beta-D-glucuronopyranosyl(1-->2)-O-beta-D-glucuronopyranosyl]-4'-O-beta-D-glucuronopyranoside, have not been reported before in the plant kingdom. Additionally, five known compounds, including apigenin 7-O-beta-D-glucuronopyranoside, apigenin 4'-O-beta-D-glucuronopyranoside, apigenin 7-O-[beta-D- glucuronopyranosyl(1-->2)-O-beta-D-glucuronopyranoside], luteolin 7-O-beta-D-glucuronopyranoside, and adenosine, were identified.

Races of Phytophthora sojae on Soybean in Illinois.

Phytophthora root rot of soybean (Glycine max (L.) Merr.), caused by Phytophthora sojae M. J. Kauffmann & J. W. Gerdemann, has been isolated throughout the soybean-producing regions of the United States. There are more than 39 identified races of P. sojae pathogenic on soybean, and 13 host resistance alleles have been identified at 7 loci (1). None of these alleles confers resistance to all races of P. sojae. The most commonly used resistance allele, Rps1k, confers resistance to the greatest number of races (2). The objective of this study was to identify races of P. sojae in Illinois soybean fields to determine whether the currently used resistance alleles are effective against the P. sojae races found in Illinois. Soybean breeders must be aware of the existence and distribution of races to incorporate appropriate sources of genetic resistance into cultivars. From 192 soil samples collected throughout Illinois in 1997, 33 isolates were obtained and identified to race by inoculating Rps isolines of soybean cv. Williams. A new race with virulence to the Rps1d and Rps7 alleles, designated as race 54, accounted for 48% of the isolates. Another new race with virulence to Rps1d, Rps3a, Rps3c, Rps4, Rps5, Rps6, and Rps7 alleles, designated race 55, was identified in one sample. One isolate, identified as race 41, was obtained from a diseased plant with the Rps1k allele. Another isolate, identified as race 43, was obtained from a diseased plant with the Rps1c allele. Based on virulence patterns of P. sojae, most of the isolates obtained from Illinois soils were races 1, 3, and 4 or variants of these races, such as race 54, with added virulence to the Rps1d allele. References: (1) A. F. Schmitthenner. 1999. Compendium of Soybean Diseases. 4th ed. G. L. Hartman, J. B. Sinclair, and J. C. Rupe, eds. The American Phytopathological Society, St. Paul, MN. pp. 39-42. (2) A. F. Schmitthenner, M. Hobe, and R. G. Bhat. Plant Dis. 78:269, 1994.

Yield and Seed Quality of Soybean Cultivars Infected with Sclerotinia sclerotiorum.

Sclerotinia stem rot (SSR) is one of the most important diseases of soybean in the United States. Five maturity group III cultivars, Asgrow A3304 STS (A3304), Pioneer Brand 9342 (P9342), Pioneer Brand 9381 (P9381), Probst, and Yale, grown in fields in east-central Illinois, were used to determine the relationship of SSR incidence to yield, 100-seed weight, seed protein and oil content, visual seed quality, and seed germination. In addition, the number of sclerotia in seed samples and the seedborne incidence of Sclerotinia sclerotiorum were determined. For each cultivar, at least 23 two-row plots, 3 m long, that represented a range of SSR incidence from low to high, were used to count the number of plants with and without SSR stem symptoms and were used to estimate yields and evaluate seed quality. Disease incidence ranged from 2 to 45% for Probst, 0 to 65% for P9381, 0 to 68% for P9342, 1 to 93% for Yale, and 0 to 95% for A3304. Regression of yields on SSR incidences for each cultivar was significant (P < 0.05); for every 10% increase in SSR incidence, yields were reduced by 147, 194, 203, 254, and 263 kg/ha for Probst, A3304, P9342, Yale, and P9381, respectively. Disease incidence was negatively correlated (P < 0.05) with seed germination for all cultivars but Probst, and to oil content and seed weight for P9381 and Yale. Disease incidence was positively correlated (P < 0.05) with seed quality for all cultivars and to the number of sclerotia in harvested seeds for P9342, P9381, and Probst. The seedborne incidence of S. sclerotiorum was 0.3, 0.3, 0.3, 0.4 and 0.7% in A3304, P9381, Yale, Probst, and P9342, respectively, and represents a significant potential for further spread of this pathogen and disease.

Rapid detection of members of the family Enterobacteriaceae by a monoclonal antibody.

Six monoclonal antibodies directed against enterobacteria were produced and characterized. The specificity of one of these antibodies (CX9/15; immunoglobulin G2a) was studied by indirect immunofluorescence against 259 enterobacterial strains and 125 other gram-negative bacteria. All of the enterobacteria were specifically recognized, the only exception being Erwinia chrysanthemi (one strain tested). Bacteria not belonging to members of the family Enterobacteriaceae were not detected, except for Plesiomonas shigelloides (two strains tested), Aeromonas hydrophila (five strains tested), and Aeromonas sobria (one strain tested). This recognition spectrum strongly suggested that CX9/15 recognized the enterobacterial common antigen. By sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot (immunoblot) experiments, the six antienterobacteria antibodies presented similar specificities; they all revealed only one band with an apparent molecular weight of about 20,000 from the crude extract of an enterobacterium. The six monoclonal antibodies, and especially CX9/15, can be used to develop new tests for rapid and specific detection of enterobacteria.