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1.
J Nematol ; 38(1): 76-82, 2006 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-19259433

RESUMEN

The soybean cyst nematode Heterodera glycines (SCN) is of major economic importance and widely distributed throughout soybean production regions of the United States where different maturity groups with the same sources of SCN resistance are grown. The objective of this study was to assess SCN-resistant and -susceptible soybean yield responses in infested soils across the north-central region. In 1994 and 1995, eight SCN-resistant and eight SCN-susceptible public soybean cultivars representing maturity groups (MG) I to IV were planted in 63 fields, either infested or noninfested, in 10 states in the north-central United States. Soil samples were taken to determine initial SCN population density and race, and soil classification. Data were grouped for analysis by adaptation based on MG zones. Soybean yields were 658 to 3,840 kg/ha across the sites. Soybean cyst nematode-resistant cultivars yielded better at SCN-infested sites but lost this superiority to susceptible soybean cultivars at noninfested sites. Interactions were observed among initial SCN population density, cultivar, and location. This study showed that no region-wide predictive equations could be developed for yield loss based on initial nematode populations in the soil and that yield loss due to SCN in our region was greatly confounded by other stress factors, which included temperature and moisture extremes.

2.
J Chromatogr A ; 915(1-2): 61-74, 2001 Apr 27.
Artículo en Inglés | MEDLINE | ID: mdl-11358263

RESUMEN

Roots from soybean cultivars Williams 82 and Hartwig along with one of their progeny 14a, were extracted with non-polar, moderately polar, and highly polar solvent systems. Extracts were compared by thin-layer chromatography and by HPLC. Methanol extractions conducted at ambient temperature coupled with analysis by reversed-phase HPLC using UV detection provided the most representative sets of reproducible fingerprints. Further optimization of the overall protocol should allow for the profiling of different soybean cultivars when their roots are exposed to various environments and insults during early growth.


Asunto(s)
Cromatografía Líquida de Alta Presión/métodos , Glycine max/clasificación , Cromatografía en Capa Delgada , Estándares de Referencia , Reproducibilidad de los Resultados , Glycine max/química , Espectrofotometría Ultravioleta
3.
Plant Dis ; 84(1): 77-82, 2000 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-30841226

RESUMEN

An experiment was conducted in Heterodera glycines-infested fields in 40 north central U.S. environments (21 sites in 1994 and 19 sites in 1995) to assess reproduction of this nematode. Two resistant and two susceptible soybean cultivars from each of the maturity groups (MG) I through IV were grown at each site in 6.1 m by 4 row plots. Soil samples were collected from each plot at planting and harvest and processed at Iowa State University to determine H. glycines initial (Pi) and final (Pf) population densities as eggs per 100 cm3 of soil. Overall, reproduction (Pf/Pi) of H. glycines on susceptible cultivars in all MG was similar. Reproduction was higher on MG III and IV susceptible cultivars than on those in MG I and II. Resistant MG I and II cultivars reduced nematode population densities more consistently than those in MG III and IV. Reproduction of the nematode was similar among sites within the same maturity zone (MZ), defined as the areas of best adaptation of the corresponding MG. Nonetheless, careful monitoring of nematode population densities is necessary to assess changes that occur over time in individual fields.

4.
J Nematol ; 32(4): 411-3, 2000 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-19270996

RESUMEN

A new apparatus to release eggs from cysts of soybean cyst nematode (Heterodera glycines) is described and its efficiency evaluated. A rubber stopper was mounted on a bolt, and cysts were ground against a 60-mesh screen. Eggs and second-stage juveniles were washed into a series of screens nested underneath the apparatus. This method was fast and efficient, and had no ill effect on prepared inoculum.

5.
Phytopathology ; 89(3): 204-11, 1999 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-18944760

RESUMEN

ABSTRACT The prevalence of brown stem rot (caused by Phialophora gregata), Heterodera glycines, and Phytophthora sojae in the north central United States was investigated during the fall of 1995 and 1996. Soybean fields were randomly selected using an area-frame sampling design in collaboration with the National Agricultural Statistics Service. Soil and soybean stem samples, along with tillage information, were collected from 1,462 fields in Illinois, Iowa, Minnesota, Missouri, and Ohio. An additional 275 soil samples collected from Indiana were assessed for H. glycines. For each field, the incidence and prevalence of brown stem rot was assessed in 20 soybean stem pieces. The prevalence and recovery (expressed as the percentage of leaf disks colonized) of P. sojae and the prevalence and population densities of H. glycines were determined from the soil samples. The prevalence of brown stem rot ranged from 28% in Missouri to 73% in Illinois; 68 and 72% of the fields in Minnesota and Iowa, respectively, showed symptomatic samples. The incidence of brown stem rot was greater in conservation-till than in conventional-till fields in all states except Minnesota, which had few no-till fields. P. sojae was detected in two-thirds of the soybean fields in Ohio and Minnesota, whereas 63, 55, and 41% of the fields in Iowa, Missouri, and Illinois, respectively, were infested with the pathogen. The recovery rates of P. sojae were significantly greater (P

6.
J Nematol ; 31(4): 498-507, 1999 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-19270922

RESUMEN

Globodera millefolii and G. artemisiae are interesting because their type localities (Estonia and Russia, respectively) are geographically distant from those of the potato cyst nematodes and other Globodera species that seem to have originated in the Western world, and because the type host for each is a member of Compositae rather than Solanaceae. Sequence data for ITS1, ITS2, and 5.8S ribosomal DNA (ITS rDNA) for G. millefolii and G. artemisiae were nearly identical to sequence data for Cactodera salina from the rhizosphere of the estuary plant Salicornia bigelovii in Sonora, Mexico. The ITS rDNA sequences of these three species were all about 94% similar to those of two other Cactodera species for which ITS rDNA data were obtained. Phylogenetic analysis indicated that, based on the ITS rDNA data, G. millefolii and G. artemisiae are more closely related phylogenetically to the Cactodera species than to other nominal Globodera species. The molecular data further suggest that the genus Cactodera may comprise two or more morphologically similar but separate groups.

7.
Theor Appl Genet ; 92(1): 83-6, 1996 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-24166120

RESUMEN

Soybean cyst nematode (SCN) is a major soybean yield-limiting pest. The present study was conducted to map broad-based SCN resistance loci from the cultivar 'Hartwig'. Two-hundred F2∶3 lines derived from the cross 'Williams 82' x 'Hartwig' were screened with a fourth-generation SCN inbred and 56 polymorphic molecular markers. Allele states and phenotypes were analyzed using stepwise regression and the model selection was made at P [Symbol: see text] 0.01. Four unlinked RFLP markers (A006, A567, A487, A112) were associated with SCN resistance and the partial coefficient of determinations (R(2)) were 91%, 1%, 1%, and 1%. We have mapped a new, major SCN resistance locus (A006) and three minor loci (A567, A487, A112). This complete mapping will accelerate the transfer of broad-based resistance without linkage drag and aid in the determination of relationships among various SCN-resistant germplasm sources.

8.
J Nematol ; 27(3): 273-83, 1995 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-19277290

RESUMEN

Ribosomal DNA (rDNA) sequence data were compared for five species of Globodera, including G. rostochiensis, G. pallida, G. virginiae, and two undescribed Globodera isolates from Mexico collected from weed species and maintained on Solanum dulcamara. The rDNA comparisons included both internal transcribed spacers (ITS1 and ITS2), the 5.8S rRNA gene, and small portions of the 3' end of the 18S gene and the 5' end of the 28S gene. Phylogenetic analysis of the rDNA sequence data indicated that the two potato cyst nematodes, G. pallida and especially G. rostochiensis, are closely related to the Mexican isolates, whereas G. virginiae is relatively dissimilar to the others and more distantly related. The data are consistent with the thesis that Mexico is the center of origin for the potato cyst nematodes.

9.
J Nematol ; 27(3): 418-22, 1995 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-19277307

RESUMEN

The number of resistance genes in soybean to soybean cyst nematode (SCN) Heterodera glycines was estimated using progeny from a cross of 'Williams 82' x 'Hartwig' (derived from 'Forrest'(3) x PI 437.654) screened with a fourth-generation inbred nematode line derived from a race 3 field population of SCN. Numbers of females developing on roots of inoculated seedlings were assigned to phenotype cells (resistant, susceptible, or segregating) using Ward's minimum variance cluster analysis. The ratio obtained from screening 220 F soybean families was not significantly different from a 1:8:7 (resistant:segregating:susceptible) ratio, suggesting a two-gene system for resistance. The ratio obtained from screening 183 F plants was not significantly different from a 3:13 (resistant:susceptible) ratio, indicating both a dominant (Rhg) and a recessive (rhg) resistance gene.

10.
J Nematol ; 26(2): 144-51, 1994 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-19279877

RESUMEN

Six geographic isolates of Heterodera avenae, including two isolates each from Sweden, Australia, and the United States, were compared on the basis of 2-D PAGE protein patterns and the complete DNA sequence for the two internal transcribed ribosomal DNA spacers (rDNA ITS1 and ITS2) and the 5.8S rRNA gene. The protein pattern data and rDNA ITS sequence data both indicated that the Swedish Gotland strain of H. avenae differed markedly from the rest of the isolates. Protein patterns for the Australia isolates differed more from a Swedish strict H. avenae isolate and isolates from Oregon and Idaho, than the two U.S. isolates and the Swedish strict H. avenae isolate differed from each other. Except for the Gotland strain isolate, the rDNA ITS sequences were highly conserved among all of the H. avenae isolates, just as we earlier found them to be conserved among species of the schachtii group of Heterodera.

11.
J Nematol ; 19(4): 431-40, 1987 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-19290167

RESUMEN

Two-dimensional polyacrylamide gel electrophoretic patterns of proteins for two isolates of Labronema from Indiana were nearly identical to the pattern for L. vulvapapillatum from Europe. The pattern for a nominal isolate of L. pacificum from Florida was very different from the patterns of nominal L. pacificum isolates from Hawaii and Fiji (which had patterns very similar to each other). Patterns for four other isolates (in Eudorylaimus and Aporcelaimellus) were different from the Labronema patterns and from each other, although some constellations of protein spots were shared among all the isolates. The study demonstrates the utility of 2-D PAGE for clarifying taxonomic problems that cannot be resolved using classical morphological data alone.

12.
J Nematol ; 18(2): 169-72, 1986 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-19294160

RESUMEN

Four of five geographical isolates of Heterodera glycines from Indiana classified as Race 3 using standard differentials showed many differences when classified using another group of differentials comprised of five soybean breeding lines and cultivars. Two isolates from northern Indiana produced cysts on more of the differentials tested than did three isolates from southern Indiana, suggesting that potential resistant lines should be tested on a range of H. glycines populations originating from the areas for which cultivars are being developed.

13.
J Nematol ; 18(2): 173-7, 1986 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-19294161

RESUMEN

Although much morphometric overlap occurs among five geographical isolates of Heterodera glycines in Indiana, significant differences in means exist among the isolates for various comparisons of second-stage juveniles. By using combinations of means, most of the isolates can be distinguished from the rest: e.g., the Vanderburgh County isolate (southern Indiana) has the longest esophagus, tail, and tail terminus; the Vigo County isolate (also from the south) has the shortest esophagus; the White County isolate (northern Indiana) has the shortest tail and tail terminus and the greatest total length; the Benton County isolate (north) is the shortest. Morphological similarities and differences do not appear to be coordinated with reproductive behavioral patterns we observed in the northern versus the southern isolates.

14.
J Nematol ; 18(2): 177-82, 1986 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-19294162

RESUMEN

Protein patterns obtained by two-dimensional polyacrylamide gel electrophoresis for three isolates of Heterodera glycines from southern Indiana appear qualitatively similar and have higher pairwise Jaccard similarity coefficients with each other than with isolates from northern Indiana. Three isolates from three northern counties share proteins not present in the southern isolates, but as a group the northern isolates are less similar to each other than are the southern Indiana isolates.

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