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Fifty genotypes of groundnut including released varieties and advanced breeding lines were used to assess the drought tolerance. These genotypes were evaluated both in managed drought stress (DS) and non stress (NS) situations during post rainy season (Jan-April), 2011 at Oilseeds Farm, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India. The drought stress was imposed by withholding irrigation after 60 days after sowing for the drought stress trial. Observations were recorded for pod yield per plant and kernel yield per plant on randomly chosen five plants per entry per replication. The data were subjected to ANOVA and drought tolerance parameter viz., drought susceptibility index (DSI) for pod yield per plant and kernel yield per plant. The results indicated that genotypes differed significantly for pod and kernel yield per plant. Among the genotypes, 7 and 6 genotypes were observed as highly drought tolerant based on pod and kernel yield per plant respectively. A total of 6 and 9 genotypes recorded as highly susceptible to drought for pod and kernel yield per plant respectively. Among these genotypes, each three drought tolerant (ICGV 91114, K1375 and ICGV 02125) and drought susceptible (ICGV 01279, ICGV 98170 and ICGV 98175) genotypes were selected for hybridization programme to develop mapping populations. [ABSTRACT FROM AUTHOR]

Three lines were crossed with seven testers in a L x T mating design to estimate combining ability for yield and its attributing traits in groundnut, Arachis hypogaea L. The variance due to specific combining ability (SCA) was greater than variance due to general combining ability (GCA) for all the characters under study except days to maturity which indicated the role of non-additive gene action in the inheritance of these characters. The parents R-2001-2, ICGV-00451, SEL-1 and GPBD-5 were identified as good general combiners for the most of the yield attributing characters as they recorded high per se with positive significant gca effects for pod yield/plant. Among 21 crosses evaluated, five crosses R-2001-2 x GPBD-5, ICGV- 91114 x KRG-1, R-2001-2 x TPT-25, ICGV-00350 x TAG-24 and ICGV-00350 x TMV-2 exhibited high and positive significant sea effects for pod yield/plant. [ABSTRACT FROM AUTHOR]

Groundnut ringspot virus (GRSV) and Tomato chlorotic spot virus (TCSV) are two emerging tospoviruses in Florida. In a survey of the southeastern United States, GRSV and TCSV were frequently detected in solanaceous crops and weeds with tospovirus-like symptoms in south Florida, and occurred sympatrically with Tomato spotted wilt virus (TSWV) in tomato and pepper in south Florida. TSWV was the only tospovirus detected in other survey locations, with the exceptions of GRSV from tomato (Solanum lycopersicum) in South Carolina and New York, both of which are first reports. Impatiens (Impatiens walleriana) and lettuce (Lactuca sativa) were the only non-solanaceous GRSV and/or TCSV hosts identified in experimental host range studies. Little genetic diversity was observed in GRSV and TCSV sequences, likely due to the recent introductions of both viruses. All GRSV isolates characterized were reassortants with the TCSV M RNA. In laboratory transmission studies, Frankliniella schultzei was a more efficient vector of GRSV than F. occidentalis. TCSV was acquired more efficiently than GRSV by F. occidental but upon acquisition, transmission frequencies were similar. Further spread of GRSV and TCSV in the United States is possible and detection of mixed infections highlights the opportunity for additional reassortment of tospovirus genomic RNAs. [ABSTRACT FROM AUTHOR]

Kunitz trypsin inhibitor (KTI), a major anti-nutritional factor present in soybean seed, is a major bottleneck in industrial use of soybean and public acceptance of soybean food products. Biochemical screening for trypsin inhibitor content was carried out in 145 genotypes of soybean comprising exotic collections and released varieties. The trypsin inhibitor content ranged from 14.15 to 186.27 mg g-1 of seed meal. Lowest level of trypsin inhibitor content was observed in genotype PI542044, (14.15 mg g-1 seed meal). Popular Indian soybean varieties viz., JS335, JS9305, NRC37, NRC7, PK1225, DS9712, JS9752, and DS9814 contained higher level of trypsin inhibitor. Heat treatment was able to reduce the TI content but to certain level leaving about 20% residual activity. The study indicated the need for other ways to create genotypes with reduced KTI for use in breeding program. [ABSTRACT FROM AUTHOR]

Members of the plant-specific IQ67-domain (IQD) protein family are involved in plant development and the basal defense response. Although systematic characterization of this family has been carried out in Arabidopsis, tomato (Solanum lycopersicum), Brachypodium distachyon and rice (Oryza sativa), systematic analysis and expression profiling of this gene family in soybean (Glycine max) have not previously been reported. In this study, we identified and structurally characterized IQD genes in the soybean genome. A complete set of 67 soybean IQD genes (GmIQD1–67) was identified using Blast search tools, and the genes were clustered into four subfamilies (IQD I–IV) based on phylogeny. These soybean IQD genes are distributed unevenly across all 20 chromosomes, with 30 segmental duplication events, suggesting that segmental duplication has played a major role in the expansion of the soybean IQD gene family. Analysis of the Ka/Ks ratios showed that the duplicated genes of the GmIQD family primarily underwent purifying selection. Microsynteny was detected in most pairs: genes in clade 1–3 might be present in genome regions that were inverted, expanded or contracted after the divergence; most gene pairs in clade 4 showed high conservation with little rearrangement among these gene-residing regions. Of the soybean IQD genes examined, six were most highly expressed in young leaves, six in flowers, one in roots and two in nodules. Our qRT-PCR analysis of 24 soybean IQD III genes confirmed that these genes are regulated by MeJA stress. Our findings present a comprehensive overview of the soybean IQD gene family and provide insights into the evolution of this family. In addition, this work lays a solid foundation for further experiments aimed at determining the biological functions of soybean IQD genes in growth and development. [ABSTRACT FROM AUTHOR]

Although the functional roles of zinc finger-containing glycine-rich RNA-binding proteins (RZs) have been characterized in several plant species, including Arabidopsis thaliana and rice (Oryza sativa), the physiological functions of RZs in wheat (Triticum aestivum) remain largely unknown. Here, the functional roles of the three wheat RZ family members, named TaRZ1, TaRZ2, and TaRZ3, were investigated using transgenic Arabidopsis plants under various abiotic stress conditions. Expression of TaRZs was markedly regulated by salt, dehydration, or cold stress. The TaRZ1 and TaRZ3 proteins were localized to the nucleus, whereas the TaRZ2 protein was localized to the nucleus, endoplasmic reticulum, and cytoplasm. Germination of all three TaRZ-expressing transgenic Arabidopsis seeds was retarded compared with that of wild-type seeds under salt stress conditions, whereas germination of TaRZ2- or TaRZ3-expressing transgenic Arabidopsis seeds was retarded under dehydration stress conditions. Seedling growth of TaRZ1-expressing transgenic plants was severely inhibited under cold or salt stress conditions, and seedling growth of TaRZ2-expressing plants was inhibited under salt stress conditions. By contrast, expression of TaRZ3 did not affect seedling growth of transgenic plants under any of the stress conditions. In addition, expression of TaRZ2 conferred freeze tolerance in Arabidopsis. Taken together, these results suggest that different TaRZ family members play various roles in seed germination, seedling growth, and freeze tolerance in plants under abiotic stress. [ABSTRACT FROM AUTHOR]

A mapping population segregating for the important nutritional quality traits (protein content, oil content and fatty acid profile) was evaluated for genetic variability and correlation among the traits. The population exhibited significant variation among the genotypes, seasons and G x E interaction. Moderate magnitude of variability followed by higher heritability was observed for most of the quality traits. Positive correlation was observed between protein and oil content, whereas, negative correlation between oleic and linoleic acid indicated their antagonistic nature. All the eight fatty acids were correlated with each other either positively or negatively. Superior RILs were identified for higher protein content, oil content, oleic acid and O/L ratio from the population. [ABSTRACT FROM AUTHOR]

Highlights: [•] GmICHG is a β-glucosidase that is exclusively localized in the root apoplast of soybean. [•] GmICHG plays a constitutive role in the production of free isoflavones in the roots. [•] Upon wounding and fungal infection of cotyledons, GmICHG was transiently up-regulated in taproots. [•] Such long-distance up-regulation was not observed with either GmIFS or GmIF7GT. [•] Transcription of GmICHG in the roots was sensitive to abiotic stresses on the roots. [Copyright &y& Elsevier]

Three experiments were carried out in pots under glass house conditions of Bangladesh Institute of Nuclear Agriculture (BINA) to assess tolerance levels of groundnut mutant genotypes/mutant varities to salinity stress. The first experiment assessed salinity levels based on reduction in shoot biomass under 8 desi siemen per meter (dS/m) salinity imposed during flowering till harvest stages of 41 mutants, 4 mutant varieties and 5 non mutant varieties including the parent of the mutants and mutant varieties. Based on the result of the first experiment 22 mutants/varieties with higher, moderate and lower shoot biomass reductions were further screened based on pod number and pod weight under the same salinity level and growth stages. It was observed that the mutants and mutant varieties attained different levels of salinity tolerance in contrast to to their parent Dacca-1 which was highly sensitive. From the third experiment, it was also revealed that the tolerant mutant/variety accumulated increased total sugar contents to that of unstressed control treatment when exposed to salinity stresses during flowering and pod filling stages and free amino acid during pod filling stage, helped maintaining turgor of guard cell and intake of CO2 through opened stomata. This CO2 in presence of undamaged chloroplast helped maintaining photosynthesis and mobilization of assimilates to reproductive organs, particularly kernel. Finally, it was concluded that it is possible to modify salinity tolerance level of a sensitive groundnut through induced mutation by directly irradiating its seed or seeds of mutant(s) derived from it. [ABSTRACT FROM AUTHOR]

Diversity analysis among released/prerelease groundnut cultures was carried out to assess the genetic relationship which helps in the documentation of the differences in the context of intellectual property rights and to identify diverse parents for use in hybridization programme for improvement of yield and other desirable traits i.e. drought resistance and foliar disease resistance etc.. Twenty-nine released and pre-release groundnut genotypes were grown during kharif season with protective irrigation in randomized block design with three replications. Data on morphological, yield and yield attributes were recorded. Diversity was analysed through Mahalanobis's D² analysis. Twenty-nine genotypes were grouped into nine clusters. Clustering pattern showed relationship with pedigree and place of breeding. Maximum contribution to diversity was by harvest index, days to emergence and length of main axis and minimum contribution was by number of mature pods per plant. [ABSTRACT FROM AUTHOR]

The success of any breeding programme depends upon the amount of variability present for different characters in a population and its efficient management. The genetic coefficient of variation is a useful measure of the magnitude of genetic variance present in the population. However, estimation of genetic variability alone cannot indicate the possible improvement that could be achieved through selection, but it should be used in conjunction with heritability and genetic advance. High heritability combined with high GAM was observed for most of the characters especially for shelling percentage, sound mature kernel weight and pod yield per plant. High heritability coupled with moderate genetic advance as percent of mean (GAM) was recorded for protein and sound mature kernel weight. Oil showed high heritability with low GAM. It was also observed that variability and heritability for chlorophyll and yield in 40 peanut genotypes and reported wide variability and moderate heritability values for chlorophyll and seed weight per plant. High GCV, PCV and heritability and genetic advance were noticed for harvest index and its component traits viz., pod yield per plant, number of branches per plant and sound mature kernel percentage. [ABSTRACT FROM AUTHOR]

Groundnut (Arachis hypogaea) is an economically important legume crop in Vietnam and many other countries worldwide. Stem and pod rot, caused by the soilborne fungus Scierotium rolfsii, is a major yield-limiting factor in groundnut cultivation. To develop sustainable measures to control this disease, fundamental knowledge of the epidemiology and diversity of S. rolfsii populations is essential. In this study, disease incidence was monitored in eight groundnut areas in central Vietnam with a total of 240 observational field plots. The results showed that 5 to 25% of the field-grown groundnut plants were infected by S. rolfsii. Based on internal transcribed spacer (ITS) ribosomal DNA sequence analyses, three distinct groups were identified among a total of 103 randomly selected S. rolfsii field isolates, with the majority of the isolates (n = 90) in one ITS group. S. rolfsii isolates originating from groundnut, tomato, and taro were all pathogenic on groundnut and relatively sensitive to the fungicide tebuconazole but displayed substantial diversity of various genetic and phenotypic traits, including mycelial compatibility, growth rate, and sclerotial characteristics. [ABSTRACT FROM AUTHOR]

Abstract: It was proposed that if some mRNA characteristics resulted in a low efficiency of termination signal, an additional closely located stop codon (tandem stop codons) could be used to prevent the harmful readthrough. However, the role of tandem terminators in higher eukaryotes was not verified and remains hypothetical. In this work the sequence features of Arabidopsis thaliana and Oryza sativa mRNAs were analyzed. It was found that plant mRNAs with UGA terminator were characterized by a higher frequency of nonsense codons in the first triplet position of 3′-UTR that could result from a weak natural selection for “reserve” stop signal. Interestingly, the presence of tandem stop codons positively correlated with a specific amino acid composition in the C-terminal position of the encoded proteins. In particular, C-terminal glycine positively correlated with significantly higher frequencies of reserve terminators at the beginning positions of 3′-UTR in UGA-containing mRNAs. This finding coincides with some earlier observations concerning the role of glycine and its codons in inefficient termination of translation and recoding (e.g., 2A oligopeptide). [Copyright &y& Elsevier]

With 6 figures and 4 tables The cultivated soybean is domesticated from the wild soybean. Nevertheless, the origin of a semi‐wild‐type (Glycine gracilis) intermediate in morphology between the wild and cultivated species has not been very clearly established. The current hypothesis is that it is formed by hybridization between wild and cultivated soybeans. However, this theory is based on molecular data and lacks undisputed evidence, owing to no actual insight into the morphological behaviour of the occurrence of natural introgression. Phenotypic evidence is required in addition to molecular analyses. We investigated wild and cultivated soybean populations and captured the process of natural introgression between wild and cultivated soybeans as the direct and crucial evidence for the interspecific gene flow. Normal wild and cultivated soybean seeds from natural and cultivated populations generated G. gracilis‐type plants, which revealed the speciation of G. gracilis type. Our results demonstrated that the semi‐wild soybean type originated from reciprocal hybridizations between wild and cultivated soybeans. Phenotypically different cytoplasmic impacts between the wild and cultivated cytoplasmic genomes occurred in G. gracilis. [ABSTRACT FROM AUTHOR]

The article presents a study which analyzes the genetic mechanism of the high alpha-tocopherol content trait of Keszthelyi Aproszemu Sarga (KAS), a variety of soybean (Glycine max). It is said that breeding methods focuses on improving alpha-tocopherol content to increase the nutritional value of crops. The study identified a gene, which encodes g-tocopherol methyltransferase, as a candidate gene responsible for high alpha-tocopherol concentration in KAS.

The article presents a study regarding the induction of genetic variability for fatty acid composition in a large-seeded groundnut variety through induced mutagenesis in India. The study utilizes TPG 41, a Spanish bunch large-seeded variety with 120 days maturity period and has been released for irrigated areas in summer season. It concludes that it is possible to induce genetic variability through induced mutagenesis for various fatty acids and yield traits.

Background: Plant roots are the primary site of perception and injury for saline-alkaline stress. The current knowledge of saline-alkaline stress transcriptome is mostly focused on saline (NaCl) stress and only limited information on alkaline (NaHCO3) stress is available. Results: Using Affymetrix® Soybean GeneChip®, we conducted transcriptional profiling on Glycine soja roots subjected to 50 mmol/L NaHCO3 treatment. In a total of 7088 probe sets, 3307 were up-regulated and 5720 were down-regulated at various time points. The number of significantly stress regulated genes increased dramatically after 3 h stress treatment and peaked at 6 h. GO enrichment test revealed that most of the differentially expressed genes were involved in signal transduction, energy, transcription, secondary metabolism, transporter, disease and defence response. We also detected 11 microRNAs regulated by NaHCO3 stress. Conclusions: This is the first comprehensive wild soybean root transcriptome analysis under alkaline stress. These analyses have identified an inventory of genes with altered expression regulated by alkaline stress. The data extend the current understanding of wild soybean alkali stress response by providing a set of robustly selected, differentially expressed genes for further investigation. [ABSTRACT FROM AUTHOR]

Background: Next generation sequencing is transforming our understanding of transcriptomes. It can determine the expression level of transcripts with a dynamic range of over six orders of magnitude from multiple tissues, developmental stages or conditions. Patterns of gene expression provide insight into functions of genes with unknown annotation. Results: The RNA Seq-Atlas presented here provides a record of high-resolution gene expression in a set of fourteen diverse tissues. Hierarchical clustering of transcriptional profiles for these tissues suggests three clades with similar profiles: aerial, underground and seed tissues. We also investigate the relationship between gene structure and gene expression and find a correlation between gene length and expression. Additionally, we find dramatic tissue-specific gene expression of both the most highly-expressed genes and the genes specific to legumes in seed development and nodule tissues. Analysis of the gene expression profiles of over 2,000 genes with preferential gene expression in seed suggests there are more than 177 genes with functional roles that are involved in the economically important seed filling process. Finally, the Seq-atlas also provides a means of evaluating existing gene model annotations for the Glycine max genome. Conclusions: This RNA-Seq atlas extends the analyses of previous gene expression atlases performed using Affymetrix GeneChip technology and provides an example of new methods to accommodate the increase in transcriptome data obtained from next generation sequencing. Data contained within this RNA-Seq atlas of Glycine max can be explored at http://www.soybase.org/soyseq. [ABSTRACT FROM AUTHOR]

In many parts of Japan cultivated soybean and wild soybean are sympatric. The objective of this study was to measure gene movement from cultivated soybean to wild soybean and within wild soybean in natural populations in Japan. Seven microsatellite markers that were found to have particularly high ability to discriminate components of the soybean complex in Japan were used to measure the extent of pollen and seed dispersal within and between populations of G. soja at seven localities (14 populations) in northern, central, and southern regions of Japan (1334 seeds/168 individuals) were measured. Each G. soja site consisted of two neighboring populations (100 m-2 km apart), which were adjacent to (<5 m), or isolated from (>50 m), cultivated soybean fields. Gene flow from G. max to G. soja was not detected. However, in populations of G. soja, the outcrossing rate ranged from 0-6.3% (average 2.2%), and the dispersal distance of pollen ranged from 5-25 m (average 10.5 m). In addition, 13 individuals of G. soja (7.7%) collected in four populations were assigned to neighboring populations (100-400 m). The results suggest the occurrence of long-distance seed dispersal in G. soja. Spatial autocorrelation analysis revealed a clear isolation by distance model, and a strong positive genetic correlation among individuals was observed within a range of 400 m (r = 0.168-0.551). Gene flow by hybridization among G. soja individuals occurs more frequently than the rare hybridization events between G. max and G. soja in Japan. [ABSTRACT FROM AUTHOR]

Mutability of the w4 flower color locus in soybean, Glycine max (L.) Merr., is conditioned by an allele designated w4-m. Germinal revertants recovered among self-pollinated progeny of mutable plants have been associated with the generation of necrotic root mutations, chlorophyll-deficiency mutations, and sterility mutations. A total of 24 necrotic root mutant lines were generated from a total of 24 independent reversion events at the w4-m locus. The initial mutable population included 4 mutable categories for w4-m, designated (1) low frequency of early excisions, (2) low frequency of late excisions, (3) high frequency of early excisions, and (4) high frequency of late excisions. These mutable categories were based upon flower phenotype, i.e., somatic tissue. A total of 22 of 24 necrotic root mutations occurred from germinal reversions classified in the high frequency of excision categories. Of these 22 mutants, 14 came from early excisions and 8 came from late excisions. These necrotic root mutants were allelic to 6 previously identified necrotic root mutants derived from the study of germinal revertants, i.e., gene tagging studies, chemical mutagenesis, and “spontaneous” occurrences from genetic crosses. Thus, all 30 necrotic root mutants in soybean are allelic. An F2 mapping population from the cross of Minsoy (Rn1 Rn1) × T328 (rn1 rn1) was used to map the Rn1 locus using simple sequence repeat (SSR) markers. The Rn1 locus was located between Satt288 and Satt612 on molecular linkage group G. [ABSTRACT FROM AUTHOR]

Soybean cyst nematode ( Heterodera glycines Ichinohe; SCN) is the primary disease responsible for yield loss of soybean [ Glycine max (L.) Merr.]. Resistant cultivars are an effective management tool; however, the sources currently available have common resistant genes. Glycine soja Sieb. and Zucc., the wild ancestor of domesticated soybean, represents a diverse germplasm pool with known SCN resistance. The objectives of this research were to: (1) determine the genetic variation and inheritance of SCN resistance in a G. max (‘S08-80’) × G. soja (PI464925B) F 4:5 recombinant inbred line (RIL) population; and (2) identify and evaluate quantitative trait loci (QTL) associated with SCN resistance. Transgressive segregation for resistance was observed, although neither parent was resistant to the Chatham and Ruthven SCN isolates. Broad sense heritability was 0.81 for the Ruthven and 0.91 for the Chatham isolate. Root dry weight was a significant covariate that influenced cyst counts. One RIL [female index (FI) = 5.2 ± 1.11] was identified as resistant to the Chatham isolate (FI < 10). Seventeen and three RILs infected with Chatham and Ruthven isolates, respectively, had mean adjusted cyst counts of zero. Unique and novel QTL, which derived resistance from G. soja, were identified on linkage groups I, K, and O, and individually explained 8, 7 and 5% (LOD = 2.1–2.7) of the total phenotypic variation, respectively. Significant epistatic interactions were found between pairs of SSR markers that individually may or may not have been associated with SCN resistance, which explained between 10 and 15% of the total phenotypic variation. Best-fit regression models explained 21 and 31% of the total phenotypic variation in the RIL population to the Chatham and Ruthven isolates, respectively. The results of this study help to improve the understanding of the genetic control of SCN resistance in soybean caused by minor genes resulting in horizontal resistance. The incorporation of the novel resistance QTL from G. soja could increase the durability of SCN-resistance in soybean cultivars, especially if major gene resistance breaks down. [ABSTRACT FROM AUTHOR]

The objectives of this study were to evaluate soybean [Glycine max (L.) Merr.] agronomic and quality traits and to examine correlations among traits in an interspecific soybean population. The agronomic traits included maturity, plant canopy height, canopy spread, leaflet length, leaflet width, seed yield, and seed size. The seed quality traits were sucrose, raffinose, and stachyose content. A total of 308 recombinant inbred lines (RIL) were developed from the cross between a large-seeded Glycine max breeding line (V71-370) and a small-seeded Glycine soja Sieb. & Zucc. accession (PI 407162). Normal distribution was observed for most of the traits with a slight skewness towards the G. soja parent. Most correlation coefficients were highly significant, such as the positive correlation between yield and sucrose and between seed size and sucrose. Genotype x environment interaction was significant for all of the agronomic traits but not for sugar contents. Maturity, seed size, and sucrose content were highly heritable, whereas plant height, canopy spread, leaflet length, leaflet width, yield, stachyose content, and raffinose content had relatively low broad-sense heritabilities. Our findings suggest that the lack of genotype x location effects on sugar content favors progress through selection, but the strong correlation among the sugars may hinder progress in selecting lines that are high in sucrose but low in raffinose and stachyose over different environmental conditions. The information on heritabililty and interrelationships among the agronomic and seed quality traits will be helpful to breeders in constructing their breeding populations and implementing selection strategies. [ABSTRACT FROM AUTHOR]

The research objectives were to determine aspects of the population dynamics relevant to effective monitoring of gene flow in the soybean crop complex in Japan. Using 20 microsatellite primers, 616 individuals from 77 wild soybean ( Glycine soja) populations were analysed. All samples were of small seed size (< 0.03 g), were directly collected in the field and came from all parts of Japan where wild soybeans grow, except Hokkaido. Japanese wild soybean showed significant reduction in observed heterozygosity, low outcrossing rate (mean 3.4%) and strong genetic differentiation among populations. However, the individual assignment test revealed evidence of rare long-distance seed dispersal (> 10 km) events among populations, and spatial autocorrelation analysis revealed that populations within a radius of 100 km showed a close genetic relationship to one another. When analysis of graphical ordination was applied to compare the microsatellite variation of wild soybean with that of 53 widely grown Japanese varieties of cultivated soybean ( Glycine max), the primary factor of genetic differentiation was based on differences between wild and cultivated soybeans and the secondary factor was geographical differentiation of wild soybean populations. Admixture analysis revealed that 6.8% of individuals appear to show introgression from cultivated soybeans. These results indicated that population genetic structure of Japanese wild soybean is (i) strongly affected by the founder effect due to seed dispersal and inbreeding strategy, (ii) generally well differentiated from cultivated soybean, but (iii) introgression from cultivated soybean occurs. The implications of the results for the release of transgenic soybeans where wild soybeans grow are discussed. [ABSTRACT FROM AUTHOR]

The soybean cyst nematode (SCN, Heterodera glycines Riggs and Niblack) is the most important soybean [Glycine max (L.) Merr.] pathogen in the USA and its control relies on genetic resistance. When resistance genes from exotic sources are transferred into elite cultivars, deleterious alleles are frequently transferred with resistance through genetic linkages. Two SCN resistance loci have been identified in G. soja Sieb. and Zucc. PI 468916, and the effect these loci have on yield and other agronomic traits is not known. The objective of this study was to determine the effect of each G. soja SCN resistance gene on yield and other agronomic traits in elite soybean backgrounds. These effects were tested in two populations each segregating for SCN resistance derived from G. soja, with one population also segregating for the SCN resistance loci, rhg1, derived from G. max PI 88788. Each population was analyzed for genetic markers linked to the SCN resistance loci and field tested in multiple environments with low to high SCN infestations. The G. soja and rhg1 SCN resistance alleles either had no effect or significantly (P < 0.05) enhanced yield compared with the susceptible alleles. The SCN resistance alleles were also associated with increasing days to maturity, plant height, and lodging scores. Deployment of the G. soja SCN resistance loci will increase the genetic diversity for SCN resistance and will provide breeders with an alternative source of SCN resistance that is not associated with reduced yield. [ABSTRACT FROM AUTHOR]

The objective of this study was to examine the distribution of rDNA loci in the genus Glycine Willd. by fluorescent in situ hybridization (FISH) using the internal transcribed spacer (ITS) region of nuclear ribosomal DNA as a probe. The hybridized rDNA probe produced two distinct yellow signals on reddish chromosomes representing two NORs in 16 diploid (2n=40) species. Aneudiploid (2n=38) and aneutetraploid (2n=78) Glycine tomentella Hayata also exhibited two rDNA sites. However, the probe hybridized with four chromosomes as evidenced by four signals in two diploid species (Glycine curvata Tind. and Glycine cyrtoloba Tind.) and tetraploid (2n=80) G. tabacina (Labill.) Benth. and G. tomentella. Synthesized amphiploids (2n=80) of Glycine canescens F. J. Herm. (2n=40) and the 40-chromosome G. tomentella also showed four signals. This study demonstrates that the distribution of the rDNA gene in the 16 Glycine species studied is highly conserved and that silence of the rDNA locus may be attributed to amphiplasty during diploidization and speciation. [ABSTRACT FROM AUTHOR]