Soybean Germ Research Articles

Breeding for Resistance to Soybean Rust.

Soybean rust occurs in all major soybean-growing regions of the world including the North American mainland. Soybean rust, caused by Phakopsora pachyrhizi, is the most destructive foliar disease of soybean, and yield losses of over 50% are common when environmental conditions are conducive for disease development. Heavily infected plants defoliate and mature more rapidly than plants not infected with rust. P. pachyrhizi has a broad host range and can infect many other legumes including some native to Australia. A number of physiological races of the fungus have been reported on these native legumes from Australia and on soybean. In addition, four single genes for rust resistance were previously identified in four different soybean plant introductions. These sources of resistance also have been reported to be susceptible in some field locations and when challenged with certain isolates of P. pachyrhizi. Partial resistance, expressed as reduced pustule number and increased length of latent period, has also been reported but has not been widely used in breeding programs. Yield stability has been used in the past and compares percentage of yields in fungicide and nonfungicide plots. Cultivars or lines with a higher percentage of yield have greater yield stability in the presence of rust. Although soybean rust only recently was found in the continental United States, a proactive project to evaluate the USDA soybean germ plasm collection for rust resistance was initiated in 2002 at the Fort Detrick plant biocontainment facility and at six international locations. Part of this project is to discover soybean lines with greater yield stability, and additional single and partial resistance. To help minimize the impact of soybean rust, the first line of defense will be fungicides, with host resistance and yield stability augmenting the long-term management of soybean rust.

Resistance to Brown Stem Rot in Soybean Germ Plasm with Resistance to the Soybean Cyst Nematode.

The soybean cyst nematode (SCN) and Phialophora gregata f. sp. sojae, the causal agent of brown stem rot (BSR), are two pathogens of soybean commonly found in the same field throughout the north-central United States. Field experiments designed to study the role of SCN-resistant germ plasm in soybean production have led to data suggesting that some sources of SCN resistance also may provide resistance to BSR. Soybean germ plasm with resistance to SCN was evaluated in greenhouse and field environments for resistance to BSR development based on the percentage of host tissue symptomatic of BSR. Comparison of SCN-resistant cultivars and plant introductions (PI) to standard BSR-resistant and -susceptible checks were conducted in two greenhouse experiments using a root-dip inoculation with a single isolate of P. gregata. For both greenhouse experiments, PI 209332 was the only source of SCN resistance with resistance to BSR similar to standard BSR-resistant checks. Nine other sources of SCN resistance, including PI 88788 and Peking, expressed BSR symptom severity similar to BSR-susceptible checks. Cultivars derived from most SCN-resistant sources, including PI 209332, also were susceptible to BSR development, while four of the five cultivars derived from PI 88788 were highly resistant to BSR development. SCN-resistant cultivars derived from PI 88788, Peking, and PI 209332 were planted along with standard BSR-resistant and -susceptible checks at two field locations naturally infested with P. gregata and SCN or P. gregata alone. As in greenhouse experiments, four of the five cultivars derived from PI 88788 expressed resistance to BSR development equal to or better than standard BSR-resistant checks at both locations. In contrast, cultivars derived from PI 209332 and Peking expressed varying levels of disease development depending on field environment. Yields observed for PI 88788-derived cultivars were higher than BSR-resistant checks regardless of the presence of SCN. Data from both greenhouse and field experiments suggest that cvs. Williams and Williams 82 may contain a gene or genes for BSR resistance that require one or more modifier genes, possibly located in the genome of PI 88788, for complete expression.

Selected Soybean Plant Introductions with Partial Resistance to Sclerotinia sclerotiorum.

Sclerotinia stem rot, caused by Sclerotinia sclerotiorum, is a major soybean (Glycine max) disease in north-central regions of the United States and throughout the world. Current sources of resistance to Sclerotinia stem rot express partial resistance, and are limited in number within soybean germ plasm. A total of 6,520 maturity group (MG) 0 to IV plant introductions (PIs) were evaluated for Sclerotinia stem rot resistance in the United States and Canada in small plots or in the greenhouse from 1995 to 1997. Selected PIs with the most resistance were evaluated for resistance in the United States and Canada in replicated large plots from 1998 to 2000. The PIs in the MG I to III tests in Urbana, IL were evaluated for agronomic traits from 1998 to 2000. The selected PIs also were evaluated with an excised leaf inoculation and petiole inoculation technique. After the 1995 to 1997 evaluations, all but 68 PIs were eliminated because of their susceptibility to Sclerotinia stem rot. In field tests in Urbana, higher disease severity in selected MG I to III PIs was significantly (P< 0.05) associated with taller plant heights and greater canopy closure. All other agronomic traits evaluated were not associated or were inconsistently associated with disease severity. MG I to III PIs 153.282, 189.931, 196.157, 398.637, 417.201, 423.818, and 561.331 had high levels of resistance and had canopies similar to the resistant checks. The resistance ratings from the petiole inoculation technique had a high and significant (P< 0.01) correlation with disease severity in the MG I and II field tests. The partially resistant PIs identified in this study can be valuable in incorporating Sclerotinia stem rot resistance into elite germ plasm.

High Frequency of Brown Stem Rot Resistance in Soybean Germ Plasm from Central and Southern China

In an effort to identify new sources of resistance to brown stem rot, caused by Phialophora gregata, 829 soybean accessions originating from 14 provinces in central and southern China and ranging in maturity from group IV to group VIII were obtained from the USDA Soybean Germplasm Collection. All accessions were inoculated in sequential evaluations in the greenhouse with three isolates of P. gregata. Putatively resistant accessions were compared statistically with resistant and susceptible standards. Two hundred forty-one, or approximately 29% of the accessions evaluated, were resistant to all three isolates of P. gregata. The percentage of resistant accessions varied among provinces, with the highest percentages identified in the provinces of Anhui, Gansu, Jiangsu, and Sichuan. Resistance to brown stem rot was not associated with maturity of the accessions or presence of soybean mosaic virus. These resistant accessions could be utilized as sources of brown stem rot resistance through integration of northern and southern soybean germ plasm.

Brown Stem Rot Resistance in Soybean Germ Plasm from Central China.

Soybean accessions from China were screened in an attempt to identify unique sources of resistance to Phialophora gregata, the cause of brown stem rot. In 1994, over 500 accessions from the USDA Soybean Germplasm Collection, University of Illinois, Urbana-Champaign, were evaluated in the field at Urbana, IL, for reaction to brown stem rot. The accessions originated from nine provinces in central China and ranged in maturity from groups II to IV. Disease assessment was based on incidence of foliar symptoms and severity of stem symptoms produced by infection with natural inoculum. Based on field results, 64 putatively resistant lines were selected and evaluated in the greenhouse by a root-dip inoculation method. Thirteen accessions with levels of resistance equal to those of resistant standards were identified from five provinces. These lines may have value as donors of unique sources of resistance to brown stem rot.

Proliferating cell nuclear antigen (PCNA/cyclin) in plant proliferating cells: immunohistochemical and quantitative analysis using autoantibody and murine monoclonal antibodies to PCNA.

Proliferating-cell nuclear antigen (PCNA), also known as cyclin, is synthesized in proliferative cells and recently was identified as DNA polymerase-delta auxiliary protein. In this paper, the association of PCNA to the proliferative cells of plants was analysed using both autoantibodies to PCNA obtained from a patient with systemic lupus erythematosus (SLE) and murine monoclonal antibodies. By immunohistochemical analysis, nuclei of cells around the growing point in soybean root tips reacted strongly with autoantibodies to PCNA in the serum from a patient with SLE. The plant PCNA in root tip cells was purified by ammonium sulfate fractionation, DEAE chromatography, and affinity chromatography. The partially purified plant PCNA was tested by immunoblotting and a 34 kD polypeptide reacted with both the human anti-PCNA autoantibody and a mouse monoclonal antibody against human PCNA (TOB 7). In addition, the purified plant PCNA reacted with both antibodies in enzyme-linked immunosorbent assay (ELISA). The binding of anti-PCNA serum to the animal PCNA was blocked by the plant PCNA in this ELISA. The association of PCNA with growing cells in plants was further confirmed by quantitative sandwich type ELISA using two murine monoclonal antibodies to PCNA, TOB7 and TO17. Those results suggested that PCNA in both plant and animal cells had the same immunological and biochemical characteristics and the plant PCNA might play an important role in cell growth, existing as it does in proliferating plant cells. The concentration of PCNA in soybean germ extract before germination was less than 5 ng ml-1 (protein concentration, 6.8 mg ml-1), but that of the root tip stem including the growing point increased to 887 ng ml-1 (protein concentration 3.8 mg ml-1) in the second day after germination.

Hydrogen Oxidation by the Host-Controlled Uptake Hydrogenase Phenotype of Bradyrhizobium japonicum in Symbiosis with Soybean Host Plants

Symbioses between uptake hydrogenase host-regulated (Hup-hr) phenotypes of Bradyrhizobium japonicum and exotic, agronomically unadapted soybean germ plasm were examined for expression of uptake hydrogenase activity. Determinations for hydrogen evolution and uptake hydrogenase activity identified five plant introduction (PI) lines which formed hydrogen-oxidizing symbioses with strains USDA 61 and PA3 6c. Hup-hr strains belonging to serogroup 94 expressed uptake hydrogenase activity in symbioses with PI 181696 and PI 219655 at rates sufficient to prevent hydrogen from escaping the nodules. The identification of soybean germ plasm forming hydrogen-oxidizing symbioses with Hup-hr bradyrhizobia potentially has implications for enhancing nitrogen fixation efficiency in soybean production.

Soybean Dwarf Virus: Experimental Host Range, Soybean Germ Plasm Reactions, and Assessment of Potential Threat to U.S. Soybean Production

Current and recent public cultivars, miscellaneous commercial cultivars, ancestral lines of Glycine max, and a broad range of leguminous and nonleguminous species were evaluated for susceptibility to strains of soybean dwarf virus (SDV). Most suceptible hosts were found within the Fabaceae with a few susceptible species in the Chyenopodiaceae and Polemoniaceae. There was greater similarity in symptoms and host range between the yellowing strain of SDV (SDV-Y) and the subterranean clover red leaf strain of SDV from New Zealand (SDV-NZ) than between SDV-Y and SDV-D (dwarfing strain) (...)

Evaluating Soybean Germ Plasm for Brown Stem Rot Resistance

Over 3.400 accessions from the USDA Soybean Germplasm Collection in maturity groups 000 to IV were evaluated between 1981 and 1984 for resistance to brown stem rot (BSR) caused by Phialophora gregata. Lines were evaluated in naturally infested fields at latitudes to which they were adapted. In 1985 and 1986, 13 early maturity, and 25 late maturity, putatively resistant lines were evaluated in replicated tests. (…)

Genetic analysis of mannose-6-phosphate isomerase in soybeans

Five mannose-6-phosphate isomerase (EC 5.3.1.8) variants were observed electrophoretically in cultivated soybeans (Glycine max (L.) Merr.) and wild soybeans (G. soja Sieb. &amp;Zucc.). Four of the five variants differed in the mobility of the two mannose-6-phosphate isomerase bands observed, while the fifth showed no enzyme activity. Several crosses involving different variants were made to study inheritance of the observed variants. The inheritance data showed that the five variants were allelic and controlled by a single locus (Mpi). The five alleles were as follows: Mpi-a (Rf 0.61 and 0.66); Mpi-b (Rf 0.66 and 0.7); Mpi-c (Rf 0.71 and 0.75); Mpi-d (Rf 0.76 and 0.80); and mpi. Mpi-a, Mpi-b, Mpi-c, and Mpi-d are codominant, and the null allele mpi is recessive. The Mpi-b allele is most common while the Mpi-d and mpi alleles are rare in both the cultivated and wild soybean germ plasm from various sources examined.Key words: Glycine max, Glycine soja, isozymes, Mpi, gel electrophoresis, allelic frequency.

Soybean Germ Plasm Evaluation for Resistance to Colletotrichum truncatum

Soybean Germ Plasm Evaluation for Resistance to Colletotrichum truncatum

Interactions of Peanut Mottle Virus Strains and Soybean Germ Plasm

Interactions of Peanut Mottle Virus Strains and Soybean Germ Plasm

Identification of Additional Soybean Germ Plasm with Resistance to Race 3 of the Soybean Cyst Nematode

Identification of Additional Soybean Germ Plasm with Resistance to Race 3 of the Soybean Cyst Nematode

Identification of Additional Soybean Germ Plasm with Resistance to Race 3 of the Soybean Cyst Nematode

Identification of Additional Soybean Germ Plasm with Resistance to Race 3 of the Soybean Cyst Nematode

Soybean seed protein electrophoresis profiles from 15 Asian countries or regions: Hypotheses on paths of dissemination of soybeans from China

Soybean [Glycine max (L.) Merr.] seed protein extracts from 1,603 accessions obtained from 15 Asian countries or regions (not including Japan) were analyzed for the presence of alleles of 2 proteins. Three alleles of the Kunitz. trypsin inhibitor orSBTI-A 2 designated asTi a,Ti b andTi c are electrophoretically distinguishable from one another by their different Rf values of 0.79, 0.75 and 0.83, respectively. The Sp1 seed protein or β-amylase has 2 alleles designatedSp1 a andSp 1 b which are electrophoretically distinguishable from one another by their Rf values 0.36 and 0.42. About 94 percent of the soybean accessions had theTi a allele. Two accessions from Korea,P.I. 157440 andP.I. 196168, do not have theSBTI-A2 protein(ti). Two accessions, one from Pakistan and the other from Korea, were identified as having theTi c allele. Only the Korean and central Indian soybean populations have a high frequency for theTi b allele. Within Korea, the soybeans from those districts that lie closest to Japan have a high frequency for theTi b allele whereas the soybeans from those districts that lie closest to China have a low frequency for theTi b allele. TheTi b allele is not present in soybeans from the Philippines, Vietnam, Thailand, Malaysia, Burma, Nepal, Pakistan, and Afghanistan. Only 1 accession each from Taiwan and Indonesia have theTi b allele. TheSp 1 a allele is not present in soybeans from Taiwan, Vietnam, Thailand, Malaysia, Indonesia, Burma, Pakistan and Afghanistan. The highest frequency for theSp1 a allele occurs in soybean germ plasm from northern India and Nepal. The soybeans from Asia (including Japan) were divided into 3 gene centers— primary, secondary, and tertiary—containing 7 germ plasm pools. Paths of dissemination of the soybean from China to the rest of Asia were developed based upon a combination of electrophoretic data and available historical, agronomic, and biogeographical literature.

Consumption and Utilization of Soyflour-Wheat Germ Diets by Heliothis Spp1, 2, 3

Larvae of Heliothis zea (Boddie) (Noctuidae) consumed significantly more of a soybean flour-wheat germ diet than did larvae of H. virescens (F.) or backcross larvae of male H. virescens × Fn female progeny from a cross between male H. virescens and female H. subflexa (Guenee). H. zea larvae also gained significantly more weight. Differences in food consumption or weight gain between H. virescens and backcross larvae were not significant. When corn cob grits were added to the soybean flour-wheat germ diet, and the soybean flour content was nearly doubled, the 2 species and the backcross used food more efficiently and gained more weight. Heliothis spp. reared on a soybean flour-wheat germ diet containing corn cob grits prepared with either high or low amounts of agar had similar growth and development parameters, but larval survival was lower with the lesser agar.