Search

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.

Phytophthora rot, caused by Phytophthora sojae, is a damaging disease of soybean (Glycine max (L.) Merr.) throughout the soybean-producing regions of the world. The discovery of new sources of resistance in soybean is vital in maintaining control of Phytophthora rot, because races of the pathogen have been discovered that can attack cultivars with commonly used resistance genes. The objectives of this study were to investigate the distribution and diversity of Phytophthora-resistant soybean in southern China and identify sources that confer resistance to multiple races for implementation into breeding programs. Soybean accessions obtained from southern China were evaluated for their response to races 1, 3, 4, 5, 7, 10, 12, 17, 20, and 25 of P. sojae using the hypocotyl inoculation technique in the greenhouse at Urbana, Illinois in 1996 and 1997. Accessions were identified that confer resistant responses to multiple races of the pathogen. These accessions may provide sources of resistance for control of Phytophthora rot of soybean in the future. The majority of the accessions with resistance to eight or more of the ten races tested were from the provinces of Hubei, Jiangsu, and Sichuan in southern China. Based on the evaluated accessions, these provinces appear to be valuable sources of Phytophthora-resistant soybean.

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.

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

Hoffman, D. D., Diers, B. W., Hartman, G. L., Nickell, C. D., Nelson, R. L., Pedersen, W. L., Cober, E. R., Graef, G. L., Steadman, J. R., Grau, C. R., Nelson, B. D., del Rio, L. E., Helms, T., Anderson, T., Poysa, V., Rajcan, I., and Stienstra, W. C. 2002. Selected soybean plant introductions with partial resistance to Sclerotinia sclerotiorum. Plant Dis. 86:971-980. 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.

The continuous replacement of neurons in the olfactory epithelium provides an advantageous model for investigating neuronal differentiation and maturation. By calculating the relative enrichment of every mRNA detected in samples of mature mouse olfactory sensory neurons (OSNs), immature OSNs, and the residual population of neighboring cell types, and then comparing these ratios against the known expression patterns of >300 genes, enrichment criteria that accurately predicted the OSN expression patterns of nearly all genes were determined. We identified 847 immature OSN-specific and 691 mature OSN-specific genes. The control of gene expression by chromatin modification and transcription factors, and neurite growth, protein transport, RNA processing, cholesterol biosynthesis, and apoptosis via death domain receptors, were overrepresented biological processes in immature OSNs. Ion transport (ion channels), presynaptic functions, and cilia-specific processes were overrepresented in mature OSNs. Processes overrepresented among the genes expressed by all OSNs were protein and ion transport, ER overload response, protein catabolism, and the electron transport chain. To more accurately represent gradations in mRNA abundance and identify all genes expressed in each cell type, classification methods were used to produce probabilities of expression in each cell type for every gene. These probabilities, which identified 9,300 genes expressed in OSNs, were 96% accurate at identifying genes expressed in OSNs and 86% accurate at discriminating genes specific to mature and immature OSNs. This OSN gene database not only predicts the genes responsible for the major biological processes active in OSNs, but also identifies thousands of never before studied genes that support OSN phenotypes.

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.

Brown stem rot (BSR), caused by Phialophora gregata (Allington & Chamberlain) W. Gams, is a vascular-foliar soybean [Glycine max (L.) Merr.] disease of the north central USA. Although yield comparisons have been made between susceptible and resistant lines, no study has evaluated yield differences between near-isogenic lines differing in brown stem rot reaction. The objective of this study was to compare brown stem rot resistant and brown stem rot susceptible near-isogenic lines for yield and other agronomic traits. In this study, five pairs of near-isogenic fines for the Rbs2 resistance gene were grown at six locations in Illinois in 1994 and nine locations in Illinois in 1995, relying on natural infection with P. gregata. Near-isogenic lines were evaluated for disease incidence (percentage of plants exhibiting brown stem rot foliar symptoms) and disease severity (degree of foliar chlorosis-necrosis) in late August and harvested in September and October. At seven locations with 13% or greater incidence of brown stem rot, a 10.6% yield advantage was associated with the resistance gene, Rbs2. At eight locations with less than 3% incidence of brown stem rot, there was no yield difference between resistant and susceptible near-isogenic lines. These results indicate that Rbs2 prevents yield loss in the presence of brown stem rot.

Rhizoctonia root rot, caused by Rhizoctonia solani Kuhn, is a soilborne disease that can cause yield loss in soybean (Glycine max). The soybean cultivar 'Savoy' has partial resistance to R. solani. 'Savoy' was crossed to 'Jack', a cultivar that is susceptible to R. solani. Progeny from this cross was evaluated in the greenhouse for reaction to R. solani. Reaction and segregation of the F2 and F3 generations to R. solani indicated that resistance behaves as a quantitative trait. Heritability estimates indicate that selection for resistance to R. solani in soybean based on F2:3 family means would be more efficient than selecting on a single F2 plant basis.

The continuous replacement of cells in the spiny lobster olfactory organ depends on proliferation of new cells at a specific site, the proximal proliferation zone (PPZ). Using representational difference analysis of cDNA, we identified transcripts enriched in the PPZ compared to the mature zone (MZ) of the organ. The 12 clones identified included four novel sequences, three exoskeletal proteins, a serine protease, two protease inhibitors, a putative growth factor, and a sequence named PET-15 that has similarity to antimicrobial proteins of the crustin type. PET-15 mRNA was only detected in epithelial cells. It was abundant in all epithelial cells of the PPZ, but was only detected in the MZ at sites of damage to the olfactory organ. PET-15 mRNA was increased by types of damage that are known to induce proliferation of new olfactory sensory neurons in the olfactory organ. It increased in the PPZ after partial ablation of the olfactory organ and in the MZ after shaving of aesthetasc sensilla. These ipsilateral effects were mirrored by smaller increases in the undamaged contralateral olfactory organ. These contralateral effects are most parsimoniously explained by the action of a diffusible signal. Because epithelial cells are the source of proliferating progenitors in the olfactory organ, the same diffusible signal may stimulate increases in both cellular proliferation and PET-15 mRNA. The uniformity of expression of PET-15 in the PPZ epithelium suggests that the epithelial cells that give rise to new olfactory sensory neurons are a subset of cells that express PET-15. © 2003 Wiley Periodicals, Inc. J Neurobiol 58: 355–368, 2004

The pigmentation of fish and crustaceans is a natural phenomenon that is part of their natural life cycle and in which carotenoids play a dominant role. Among aquaculture species, particularly salmonid fish and shrimp, color is an important quality criterion for consumers. A similar case is evident in the aquatic ornamental industry, in which most fish species are selected and kept based on their attractive skin color. This chapter reviews the biological, practical, and regulatory considerations of carotenoids as pigmenting sources in aquaculture feed and their relevance to enhancing the sensory and color quality of fish and crustaceans.

The relations between parental bonding and attachment constructs and borderline personality disorder features were examined in a sample of 393 18-year-old participants. Hierarchical regression analyses revealed that parental bonding and attachment scores (especially insecure attachment, anxious or ambivalent attachment, and a perception of a relative lack of caring from one's mother) were uniquely associated with borderline features beyond what could be accounted for by gender, childhood adversity experiences, Axis I disorder, and nonborderline Axis II symptoms. Although relatively modest, these relations suggest that bonding and attachment constructs might be considered in comprehensive etiological models of borderline personality disorder.

Recurrent selection for high seed oil content was carried out with 2,008 progeny of 28 plants regenerated via embryogenesis, 95 via organogenesis and 25 from protoplasts via organogenesis from five different soybean cultivars. Two lines derived from plants regenerated from the cultivar Jack with small increases in seed oil content emerged after three selection cycles in the field but in both cases the protein content was decreased and the seed yield of one of the lines was also decreased. Apparently somaclonal variation for seed oil content can arise, but on the basis of the decreases in protein and yield found in this study, this small change is not useful for soybean improvement.

Brown stem rot (BSR) of soybean [Glycine max (L.) Merr.] is caused by the fungal pathogen Phialophora gregata (Allington & D.W. Chamberlain) W. Gams and occurs in soybean production areas around the world, Brown stem rot resistance genes Rbs 1 , Rbs 2 , and Rbs 1 have been identified in soyhean germplasm and plant introductions through traditional genetic analyses. Resistance to BSR has been shown to reduce yield losses in soybean, but selection for this trait is laborious and confounded by environmental variation, The objectives of this study were to identify molecular markers linked to BSR resistance genes Rbs 1 and Rbs 2 , and map these genes in the soybean genome, Genetic families of populations segregating for Rbs 1 and Rbs 2 were evaluated in the greenhouse for BSR phenotypic reaction and identified as resistant, segregating, or susceptible. Leaf tissue collected from members of F 2:3 families was bulked and DNA simple sequence repeat (SSR) marker analysis was used to identify markers that cosegregated with BSR reaction phenotypes. Five pairs of Rbs 2 near-isogenic lines were subjected to a similar analysis to verify results obtained from marker analysis conducted on the population segregating for Rbs 2 . Results of marker analyses indicated that SSR markers Satt215 and Satt431 were linked to Rbs 1 and that Satt244 and Satt431 were linked to Rbs 2 . Marker-assisted selection in the Rbs 1 (using Satt431) and Rbs 2 (using Satt244) populations would have correctly predicted 88 and 82%, respectively, of the BSR reaction phenotypes. The Rbs 1 and Rbs 2 loci map to Molecular Linkage Group J and lie in a region known to contain Rbs 1 . This region also contains loci conditioning resistance to taxonomically diverse fungal pathogens and a locus affecting nodulation in response to a bacterial symbiont.

Transposable element systems have been proposed to explain instability in floral pigmentation of several plant species, including soybean [Glycine max (L.) Merr.]. Soybean lines with chimeric (purple and pink sectored) flowers are hypothesized to contain wp-m, an active transposable element that is able to excise from the wp locus during morphological development. The objectives of this research were (i) to determine the inheritance of the chimeric flower phenotype when crossed to stable pink or purple flowered revertant lines and (ii) to determine the effect of wp on agronomic traits in stable flowered lines derived from wp-m. Chimeric flowers crossed to pink flowered revertant (wp * ) lines produced four F 2 populations with unusual segregation ratios of 52 pink, three purple, and two chimeric flowered plants. Crossing chimeric flowers to revertant purple flowered (Wp * ) lines resulted in F 2 populations that did not have the chimeric flower phenotype evident. In the agronomic evaluations, stable wp * lines were later in maturity and averaged 4 g kg -1 higher in protein content and 3 g kg -1 lower in oil content than Wp * lines. The data suggest wp acts in a pleiotropic manner to influence protein synthesis, as purple flowered revertant lines from a pink flower source had lower protein content than sister lines with wp * . Pink flowered lines derived from a purple flower source had higher levels of protein than sister lines with Wp * . The influence of wp on the anthocyanin pathway, plant morphology, and protein accumulation is a unique phenomenon that has not been reported in other plant species.

A novel, multicolored flower trait with pink and purple sectors or pink and purple flowers on the same plant was found in the soybean line LN89-5320-8-53 that was derived from stocks containing the wp allele for pink flower color. Some all purple flowered or all pink flowered lines derived from the original mutable plant were inherited in a stable manner. However, many plants that are all pink or all purple flowered do not remain stable and they switch back to other phenotypes during inbreeding. High rates of somatic instability and reversions of the wp locus were observed during self-fertilization in which the percent of plants with multicolored flowers ranged from 0.3 to 28%. In contrast to the behavior of this trait during selfing, the instability of the wp-m allele is not transmissible during outcrossing and stabilizes to the recessive pink phenotype in the F2 plants. In addition, we demonstrate that other mutable alleles for seed color (r-m) and flower color (w4-m) do not interact genetically with stable pink derivatives of the wp-m allele when combined by crossing. In addition, the mutability of the w4-m allele is also reduced in crosses to the pink line. Similarly, stable white derivatives of the w4-m locus are not activated by the wp-m mutable allele. The opposite behaviors displayed by the wp-m mutable allele during selfing and outcrossing is unusual compared to other unstable soybean alleles and to mutable alleles resulting from transposable element insertions and excisions in many plant genes. Finally, we demonstrate that novel soybean seed coat colors are produced by a pleiotropic effect of the wp/wp flower color genotype in combination with the homozygous i/i genotype for seed color and that the wp, i, and t loci segregate independently.

Capitella capitata (Fabricius) (Annelida: Polychaeta) is considered to be a species complex in many areas. An individual C. capitata was collected from the Scottish west coast bearing eggs of both Type 1 (small worms with small number of large eggs, lecithotrophic development) and Type 2 (large worms with large number of small eggs, planktotrophic development) (sensu Pearson & Pearson 1991). This appears to be the first record of such an occurrence and egg morphometrics compare with Pearson & Pearson's (1991) data for other Type 1 and Type 2 eggs. Field evidence for poecilogony is advanced.

Phytophthora sojae (Kauffmann and Gerdemann) is the causal agent of phytophthora root and stem rot of soybean [Glycine max (L.) Merr.]. A disease outbreak in favorable environmental conditions has the potential to inflict 100% yield loss. Soybean accessions from central China offer unique genetic variability and are potential sources for novel genes conferring phytophthora resistance. Approximately 500 accessions have been classified for reaction to races 1, 3, and 7 of P. sojae. Eighteen accessions were selected that were resistant to races 1 and 3 and susceptible to race 7. RFLP markers linked to resistance alleles were used to compare the accessions to isolines with known Rps alleles. Restriction fragment length polymorphism (RFLP) results were supported with greenhouse hypocotyl inoculations with zoospores of races 1, 3, 5, 8, 12, 13, and 25. One plant introduction (PI) was found likely to possess Rpsla, five possibly possessed Rps2, seven could carry Rps3, and four were found possibly to possess Rps4. Evidence of multigene combinations were detected in eight accessions. Unique RFLP bands and hypocotyl inoculation reactions were discovered in PIs 567343, 567530, 567572A, 567574A, 567583A, 567764, and 567766, implying possible presence of novel Rps alleles. Knowledge of which Rps allele combinations are present in these accessions will allow for integration of the novel resistance into modern cultivars.

Since Phytophthora sojae Kauf. & Gerde. is constantly evolving new races that overcome the resistance genes that have been deployed in soybean cultivars [Glycine max (L.) Merr.], the search for new sources of resistance is important in breeding programs involving disease management strategies. No systematic screening of the germplasm collection has been made that would give us an indication of the prevalence and distribution of phytophthora resistance in China. The objective of this study was to examine the distribution of Phytophthora resistant soybean in central China. By means of hypocotyl inoculation in the greenhouse, lines from central China were classified for their reaction to Races 1, 3, 7, and 25 of P. sojae in 1993 and 1994 at Urbana, IL, and Wooster, OH. Resistance was more frequent in the eastern provinces with the origin of Rps1-d in central China. Any searches for new P. sojae resistance genes in soybean should be focused on the Chinese provinces (Anhui and Jiangsu) with the highest incidence of resistant soybean lines.

Several chemically mutagenized lines of soybean [Glycine max (L.) Merr.] have shown enhanced nodulation and partial tolerance to high NO 3 - levels. Previous genetic analyses of hypernodulating or supernodulating soybean mutants indicated that they were genetically controlled by recessive monogenes following simple Mendelian principles. In the present study, we determined the genetic control of hypernodulating mutants selected from two soybean cultivars, Williams and Enrei, and analyzed the allelism of mutant genes controlling the hypernodulating phenotypes. Reciprocal crosses between four hypernodulating mutants (NOD1-3, NOD2-4, NOD4, and En6500) and two normally nodulated cultivars (Williams 82 and Harosoy 63) were made. The patterns of nodulation in F 1 s, F 2 s, and F 2:3 progeny were visually evaluated at 14 d after planting in the greenhouse. Chi squares for each progeny and homogeneity tests for each cross were calculated. The results indicated that hypernodulation in the mutants studied was conditioned by single recessive genes. Three mutants (NOD1-3, NOD4, and En6500) were controlled by a single recessive allele rj 7 , although they were isolated from distinctly different genetic materials. The allelism study indicated that another non-allelic mutant gene was identified which was responsible for hypernodulation in mutant NOD2-4. This new gene has been tentatively designated rj 8 . With respect to genetic interaction between the two mutant genes identified, the segregation ratio in the F 2 did not fit a classical pattern and therefore we speculated that these two genes interact to modify expression in an unknown fashion. Hence, additional genetic analysis is needed to clarify the genetic interaction between rj 7 and the proposed rj 8 gene.

Transformation of soybean [Glycine max (L.) Merr.] with a gene encoding a glyphosate-tolerance 5-enolpyruvylshikimate-3-phosphate synthase enzyme from Agrobacterium sp. strain CP4 resulted in the development of glyphosate-tolerant line 40-3-2. Glyphosate (N-phosphonomethyl glycine) is the active ingredient of Roundup herbicide. Line 40-3-2 was yield tested at 17 locations in 1992, 23 locations in 1993, and 18 locations in 1994. At those locations, broadcast applications of glyphosate at various rates were made over 40-3-2 or its derivatives from early vegetative growth to pod fill. No significant yield reduction was observed as a result of the glyphosate treatment at any of the locations. Development of glyphosate-tolerant soybean promises to provide the farmer with access to a new weed control system that should result in lower production costs and reliable weed control under a wide range of conditions.

Several genes act epistatically to produce flower color in soybean [Glycine max (L.) Merr.]. The genotype W1W1W3W3w4w4 produces the purple-throat phenotype and W1W1w3w3w4w4 gives a near-white phenotype. Our objective was to determine whether restriction fragment length polymorphisms of several anthocyanin pathway genes are associated with flower color traits. Genomic DNA from isolines of several flower color genes in the cultivar Clark were digested with 23 different endonucleases and probed with clones representing phenylalanine ammonia lyase, chalcone synthase, or dihydroflavonal reductase (DFR). The HaeIII digest revealed a polymorphism between the isoline containing the dominant W3 allele for purple-throat and the other isolines with the homozygous recessive w3 alleles. The DFR polymorphism cosegregated with flower color variants in an F 2 population segregating for the W3 alleles. No recombinant types were found in 78 individuals, indicating either the W3 encodes DFR or is closely linked to a DFR gene.

Manganese deficiency is a recurring problem in soybean [Glycine max (L.) Merr.] grown on high pH soils. Presently, the application of chemical fertilizers is used to alleviate yield losses associated with this deficiency. Because chemical control is often ineffective, genetic tolerance could be used in areas where Mn deficiency is a problem. The development of soybean genotypes tolerant to Mn deficiency is facilitated if the mode of inheritance is understood. The F 2 and F 2:3 progeny of the tolerant germplasm line A14 and the intolerant cultivar Pride B216 were evaluated in the field for tolerance to Mn deficiency. The observed wide range in progeny response to Mn deficiency suggested digenic inheritance. This model was supported by the results of a cluster analysis applied to the F 2:3 family mean ratings and variances. Low estimates of narrow sense heritability (k 2 = 0.19) in the F 2 generation indicated that F 2 phenotypic differences were largely due to environmental variation, thereby making yield selection for tolerance to Mn deficiency in the F 2 generation difficult. Estimates of narrow sense heritability based on F 2:3 family means were greater (h 2 = 0.70), indicating that selection based on F 2:3 family means should be effective.

Manganese (Mn) deficiency is a problem in soybeans grown on high pH soils, which to date can only be controlled by chemical fertilizers. In view of the success of genetic resistance in reducing yield losses associated with iron (Fe) deficiency chlorosis, a one year study was initiated to determine whether genetic resistance could be used to control Mn deficiency related yield losses. For this study, twenty soybean genotypes ranging from Group I maturity to Group III maturity were planted at five locations which had previously exhibited symptoms of Mn deficiency. Individual plots were rated for Mn‐deficiency symptoms on a 1–5 scale (1 = no yellowing to 5 = severe yellowing with some necrosis) at the Rl growth stage and plants in the center rows were harvested for yield. The mean Mn‐deficiency rating was 2.8 with a range from 1.8 for NKS 23–03 and P9181 to a 3.9 for A3205. The mean yield was 3059.3 kg/ha with a range from 3670.6 for A3205 to 2567.5 kg/ha for Chapman. The correlation between Mn‐defi...

The effect of boron (B), zinc (Zn), and manganese (Mn) deficiency in the medium on eight soybean genotypes was evaluated using friable callus after a 21 day growth period. Of the three micronutrients evaluated, Zn and B deficiencies had the greatest effect on callus weight, while Mn had only a slight effect. Despite this, significant differences in callus weight reduction of the eight genotypes tested were observed on the three different media. These results indicate that genotypic variation for response to B, Zn, and Mn deficiency is present in soybean at the cellular level. If the resistant genotypes identified in this study are also resistant at the whole plant level, then they could be used in soils which are deficient in the above micronutrients.

Sudden death syndrome (SDS), caused by Fusarium solani (Mart.) Sacc., can cause severe yield reduction in soybean [Glycine max (L.) Merr.]. We evaluated SDS leaf symptom development on six cultivars considered SDS-susceptible and six considered SDS-resistant. Microplot treatments used local noninfested soil inoculated (using an oat-based inoculum) with a pathogenic F. solani isolate from Arkansas; soil from two different F. solani-infested sites in Illinois; and, as a control, local noninfested soil. Plants were rated for severity and incidence of SDS leaf symptoms every 5 d from R1 through R6 developmental stages (.)

The evaluation of soybean genotypes for resistance to iron deficiency through field experiments is complicated by variation in symptom expression. The objective of this study was to develop a tissue culture technique that could distinguish between Fe‐efficient and Fe‐inefficient genotypes. Ten soybean genotypes varying in sensitivity to iron deficiency were planted at 5 locations and rated based on chlorosis expression. For the lab evaluation, friable callus of the ten genotypes was placed on a 4MSII medium amended with 10 mM NaHCO3. Callus growth reduction relative to a control medium without NaHCO3 was recorded. Callus weight of all cultivars was affected by the addition of NaHCO3 however, significant differences in growth reduction among genotypes was observed. The high correlation between callus growth reduction and field chlorosis ratings observed (r2=0.92) and the fact that the expiant source plant can be grown to produce seed indicates that this technique would be useful in a soybean breed...

Resistance to brown stem rot of soybean has been identified and utilized in cultivar development and germ plasm enhancement. However, little is known about the nature of resistance to this disease. In an attempt to better understand the resistance mechanism by locating the tissue or tissues responsible for resistance, reciprocal grafts were made between brown stem rot-resistant and -susceptible genotypes including near-isogenic lines for resistance gene Rbs2. Results of brown stem rot evaluation of grafted plants indicate that brown stem rot resistance is conditioned by the root in all resistance sources evaluated.

The objectives of this study were: (i) to develop a tissue culture technique for the evaluation of Fe efficiency in soybean, and (ii) to compare the laboratory technique with field Fe chlorosis scores. Nineteen genotypes that had low and high levels of Fe efficiency were evaluated in the laboratory and at five field locations. Friable callus was induced from epicotyl sections, weighed, and placed on two different modified Murashige and Skoog media; one low in α-naphthaleneacetic acid and the other low in Fe. Callus growth was rated as lack of growth compared to respective controls. As an example, Fe-inefficient cultivars ('Asgrow A3205' and 'Pride B216') had significantly reduced growth compared to Fe-efficient germ plasm lines ('All' and 'A14'). Correlation between the laboratory and field chlorosis rating was highest for the low auxin medium (r (2) = 0.78), although correlation for the low Fe medium was also significant (r (2) = 0.72). These results show that in vitro evaluation for Fe efficiency can be a useful tool for plant breeders.

The olfactory epithelium has the unusual ability to replace its neurons. We forced replacement of mouse olfactory sensory neurons by bulbectomy. Microarray, bioinformatics, and in situ hybridization techniques detected a rapid shift in favor of pro-apoptotic proteins, a progressive immune response by macrophages and dendritic cells, and identified or predicted 439 mRNAs enriched in olfactory sensory neurons, including gene silencing factors and sperm flagellar proteins. Transcripts encoding cell cycle regulators, axonogenesis proteins, and transcription factors and signaling proteins that promote proliferation and differentiation were increased at 5--7 days after bulbectomy and were expressed by basal progenitor cells or immature neurons. The transcription factors included Nhlh 1, Hes 6, Lmyc 1, c-Myc, Mxd 4, Id 1, Nmyc 1, Cited 2, c-Myb, Mybl 1, Tead 2, Dp 1, Gata 2, Lmo 1, and Sox1 1. The data reveal significant similarities with embryonic neurogenesis and make several mechanistic predictions, including the roles of the transcription factors in the olfactory sensory neuron lineage.

The pathogen Phytophthora sojae (M.J. Kaufmann and J.W. Gerdemann) can be injected into soybean pods [Glycine max (L.) Merr.] to determine presence of phytophthora root and stem rot resistance. The objective of this study was to use pod inoculation in the field to screen soybean F 2 populations segregating for Rps alleles. The potential exists to inject different races of the pathogen into pods at different nodes of a single plant, allowing for multiple screenings at a time. Controlling the amount of Phytophthora sojae pathogen injected into each pod was necessary for accurate scoring of disease progression. Injecting 25 μL of Race 1 or Race 3 mycelium inoculum gave optimal symptom differences. The amount of disease progression up the pod to the point of attachment or the complete lack of rotting was determined to distinguish between susceptible and resistant plants, respectively. The data obtained from scoring pods conformed well to ratios of expected models. This technique provides a rapid and inexpensive field screening for identifying resistant or susceptible progeny early in the selection process.

Enhanced nodulation and dinitrogen fixation by soybean [Glycine max (L.) Merr.] has been proposed to increase yield relative to normal nodulating types. This study was conducted to determine if two hypernodulating soybean mutants (NOD4 and NOD1-3) were capable of increased yield, compared with normal nodulating cultivars Williams 82 and Hobbit 87, and a non-nodulating check (NN5). Performance data were collected in 1990 and 1991 from a replicated design using two row-widths, 18 and 76 cm, at three locations in east central Illinois, Dwight, Champaign and Urbana [...]

Most soybean [Glycine max (L.) Merr.] cultivars and plant introductions have either purple (Wl) or white (wl) flowers. Pink (wp) flower color results when the homozygous wp alleles are combined with Wl. This study was conducted to determine the effect of pink flower color on agronomic traits in soybean. Pink and near-isogenic purple-flowered lines were derived from an F₄ plant. Seven homozygous pink-flowered, three homozygous purple-flowered, and two lines segregating for pink and purple flower color were evaluated at three locations in Illinois for 2 yr. When pink-flowered lines were compared to purple-flowered lines no differences were found for yield, maturity, height, lodging, or seed quality, while significant (P < 0.05) differences were found for seed weight, protein, and oil concentration. Pinkflowered lines averaged 22% higher in seed weight, 4% higher in protein, and 3% lower in oil compared to the purple-flowered lines. The pink flower trait represents unique germplasm in soybean that can be used in the development of high yielding cultivars with increased seed protein. Contribution from the Illinois Agric. Exp. Stn., Urbana. Research supported in part by the Illinois Soybean Operating Board and Illinois Crop Improvement Assoc.

A number of genes have been identified that affect root nodule formation in soybean [Glycine max (L.) Merr.] when inoculated with Bradyrhizobium japonicum (Kirchner) Buchanan. The non-nodulating mutant, NN5, used in this study was isolated from N-nitroso-N-methylurea mutagenized Williams seed. The objectives of this study were to determine the number of genes responsible for non-nodulation in NN5 and the relationship between the genes in NN5 and the other known non-nodulation genes (.)

Normal levels of linolenic acid (70-80 g kg -1 ) in soybean [Glycine max (L.) Merr.] oil adversely affect oil flavor and stability. The mutation-induced line C1640 has half the normal level of linolenic acid (37 g kg -1 ), but is 24% lower yielding than «Century», from which it was selected. This study was conducted to determine if there are genetic relationships between agronomic traits and the fan allele for low linolenic acid identified in C1640. Century and «Harper», both with the FanFan alleles for normal 18:3, were crossed with C1640 containing the fanfan alleles for low 18:3 (.)

Genetic analyses have indicated that brown stem rot (BSR) resistance in soybean is conferred by dominant alleles at three independent loci, the actions of which may be modified by linked or independent loci. A study was conducted to characterize the inheritance of BSR resistance in PI 567609, a soybean plant introduction from China. Segregating progeny from crosses of PI 567609 with BSR-susceptible and -resistant genotypes were evaluated for response to BSR-causal fungus, Phialophora gregata. Genetic analyses indicated that PI 567609 carries a single gene or cluster of linked genes for brown stem rot resistance, and that this gene (or cluster) is allelic to, or tightly linked to previously identified resistance genes, Rbs1, Rbs2, and Rbs3. Because previous allelism tests indicated that Rbs1, Rbs2, and Rbs3 were unlinked, and molecular mapping studies have indicated that Rbs1, Rbs2, and Rbs3 are linked on molecular linkage group J of soybean, a new model is proposed for BSR resistance. In this model, BSR resistance is controlled through the interaction of alleles at four independent loci, at least two of which are necessary to condition a resistance response. Functional redundancy at three of these loci allows any one of the three to interact with a fourth locus to confer resistance to BSR.

Previous studies have reported a correlation between genome size and relative maturity among plant species. The objective of this study was to determine whether such a relationship exists in soybean. Twenty cultivars, representing maturity groups ranging from 000 to IX, were analyzed using flow cytometric procedures. A 15% difference in genome size was observed ranging from ‘BSR 201’ at 2.88 pg to ‘Maple Presto’ at 2.51 pg. A highly significant correlation (r = 0.55) was observed between maturity and the genome size of the 20 cultivars.

Genetic alterations of regenerated plants based on the tissue culture process (somaclonal variation) have become common for many plant species including soybean [Glycine max (L.) Merr.]. The objective of this study was to test for the presence of tissue-culture-derived genetic variation in eight agronomic traits in homozygous progeny regenerated by organogenesis using the commercially important cultivar Asgrow ‘A3127.’ A total of 86 lines derived by repeated self-pollination of nine regenerated plants was grown in two locations for 2 years. When compared to the unregenerated parent, statistically significant variation (P