Hydrophobic Protein Synthesized in the Pod Endocarp Adheres to the Seed Surface

Soybean (Glycine max [L.] Merr.) hydrophobic protein (HPS) is an abundant seed constituent and a potentially hazardous allergen that causes asthma in persons allergic to soybean dust. By analyzing surface extracts of soybean seeds with sodium dodecyl sulfate-polyacrylamide gel electrophoresis and amino-terminal microsequencing, we determined that large amounts of HPS are deposited on the seed surface. The quantity of HPS present varies among soybean cultivars and is more prevalent on dull-seeded phenotypes. We have also isolated cDNA clones encoding HPS and determined that the preprotein is translated with a membrane-spanning signal sequence and a short hydrophilic domain. Southern analysis indicated that multiple copies of the HPS gene are present in the soybean genome, and that the HPS gene structure is polymorphic among cultivars that differ in seed coat luster. The pattern of HPS gene expression, determined by in situ hybridization and RNA analysis, shows that HPS is synthesized in the endocarp of the inner ovary wall and is deposited on the seed surface during development. This study demonstrates that a seed dust allergen is associated with the seed luster phenotype in soybean and that compositional properties of the seed surface may be altered by manipulating gene expression in the ovary wall.     

Gene amplification of the Hps locus in Glycine max

Background  

Hydrophobic protein from soybean (HPS) is an 8 kD cysteine-rich polypeptide that causes asthma in persons allergic to soybean dust. HPS is synthesized in the pod endocarp and deposited on the seed surface during development. Past evidence suggests that the protein may mediate the adherence or dehiscence of endocarp tissues during maturation and affect the lustre, or glossiness of the seed surface.     

The Hermansky-Pudlak syndrome 3 (cocoa) protein is a component of the biogenesis of lysosome-related organelles complex-2 (BLOC-2)

Hermansky-Pudlak syndrome (HPS) is a genetically heterogeneous inherited disease affecting vesicle trafficking among lysosome-related organelles. The Hps3, Hps5, and Hps6 genes are mutated in the cocoa, ruby-eye-2, and ruby-eye mouse pigment mutants, respectively, and their human orthologs are mutated in HPS3, HPS5, and HPS6 patients. These three genes encode novel proteins of unknown function. The phenotypes of Hps5/Hps5,Hps6/Hps6 and Hps3/Hps3,Hps6/Hps6 double mutant mice mimic, in coat and eye colors, in melanosome ultrastructure, and in levels of platelet dense granule serotonin, the corresponding phenotypes of single mutants. These facts suggest that the proteins encoded by these genes act within the same pathway or protein complex in vivo to regulate vesicle trafficking. Further, the Hps5 protein is destabilized within tissues of Hps3 and Hps6 mutants, as is the Hps6 protein within tissues of Hps3 and Hps5 mutants. Also, proteins encoded by these genes co-immunoprecipitate and occur in a complex of 350 kDa as determined by sucrose gradient and gel filtration analyses. Together, these results indicate that the Hps3, Hps5, and Hps6 proteins regulate vesicle trafficking to lysosome-related organelles at the physiological level as components of the BLOC-2 (biogenesis of lysosome-related organelles complex-2) protein complex and suggest that the pathogenesis and future therapies of HPS3, HPS5, and HPS6 patients are likely to be similar. Interaction of the Hps5 and Hps6 proteins within BLOC-2 is abolished by the three-amino acid deletion in the Hps6(ru) mutant allele, indicating that these three amino acids are important for normal BLOC-2 complex formation.     

The Hermansky-Pudlak syndrome 1 (HPS1) and HPS4 proteins are components of two complexes,BLOC-3 and BLOC-4, involved in the biogenesis of lysosome-related organelles

Hermansky-Pudlak syndrome (HPS) is a genetic disease of lysosome, melanosome, and granule biogenesis. Mutations of six different loci have been associated with HPS in humans, the most frequent of which are mutations of the HPS1 and HPS4 genes. Here, we show that the HPS1 and HPS4 proteins are components of two novel protein complexes involved in biogenesis of melanosome and lysosome-related organelles: biogenesis of lysosome-related organelles complex-(BLOC) 3 and BLOC-4. The phenotypes of Hps1-mutant (pale-ear; ep) and Hps4-mutant (light-ear; le) mice and humans are very similar, and cells from ep and le mice exhibit similar abnormalities of melanosome morphology. HPS1 protein is absent from ep-mutant cells, and HPS4 from le-mutant cells, but le-mutant cells also lack HPS1 protein. HPS4 protein seems to be necessary for stabilization of HPS1, and the HPS1 and HPS4 proteins co-immunoprecipitate, indicating that they are in a complex. HPS1 and HPS4 do not interact directly in a yeast two-hybrid system, although HPS4 interacts with itself. In a partially purified vesicular/organellar fraction, HPS1 and HPS4 are both components of a complex with a molecular mass of approximately 500 kDa, termed BLOC-3. Within BLOC-3, HPS1 and HPS4 are components of a discrete approximately 200-kDa module termed BLOC-4. In the cytosol, HPS1 (but not HPS4) is part of yet another complex, termed BLOC-5. We propose that the BLOC-3 and BLOC-4 HPS1.HPS4 complexes play a central role in trafficking cargo proteins to newly formed cytoplasmic organelles.     

RFLP markers associated with soybean cyst nematode resistance and seed composition in a ‘Peking’בEssex’ population

 Soybean cyst nematode (SCN), Heterodera glycines Ichinohe, causes severe damage to soybean [Glycine max (L.) Merr] throughout North America and worldwide. Molecular markers associated with loci conferring SCN resistance would be useful in breeding programs using marker-assisted selection (MAS). In this study, 200 F_2:3 families derived from two contrasting parents, SCN-resistant ‘Peking’ with relatively low protein and oil concentrations, and SCN-susceptible ‘Essex’ with high protein and oil concentrations, were used to determine loci underlying the SCN resistance and seed composition. Three different SCN Race isolates (1, 3, and 5) were used to screen both parents and F_2:3 families. The parents were surveyed with 216 restriction fragment length polymorphism (RFLP) probes with five different restriction enzymes. Fifty-six were polymorphic and contrasted with trait data from bioassays to identify molecular markers associated with loci controlling resistance to SCN and seed composition. Five RFLP markers, A593 and T005 on linkage group (LG) B, A018 on LG E, and K014 and B072 on LG H, were significantly linked to resistance loci for Race 1 isolate, which jointly explained 57.7% of the total phenotypic variation. Three markers (B072 and K014, both on LG H; T005 on LG B) were associated with resistance to the Race 3 isolate and jointly explained 21.4% of the total phenotypic variation. Two markers (K011 on LG I, A963 on LG E) associated with resistance to the Race 5 isolate together explained 14.0% of the total phenotypic variation. In the same population we also identified two RFLP markers (B072 on LG H, B148 on LG F) associated with loci conferring protein concentration, which jointly explained 32.3% of the total phenotypic variation. Marker B072 was also linked to loci controlling the concentration of seed oil, which explained 21% of the total phenotypic variation. Clustering among quantitative trait loci (QTLs) conditioning resistance to different SCN Race isolates and seed protein and oil concentrations may exist in this population. We believe that markers located near these QTLs could be used to select for new SCN resistance and higher levels of seed protein and oil concentrations in breeding improved soybean cultivars. Received: 3 March 1998 / Accepted: 18 August 1998     

Genome-wide association mapping for seed protein and oil contents using a large panel of soybean accessions

Soybean is globally cultivated primarily for its protein and oil. The protein and oil contents of the seeds are quantitatively inherited traits determined by the interaction of numerous genes. In order to gain a better understanding of the molecular foundation of soybean protein and oil content for the marker-assisted selection (MAS) of high quality traits, a population of 185 soybean germplasms was evaluated to identify the quantitative trait loci (QTLs) associated with the seed protein and oil contents. Using specific length amplified fragment sequencing (SLAF-seq) technology, a total of 12,072 single nucleotide polymorphisms (SNPs) with a minor allele frequency (MAF)?≥?0.05 were detected across the 20 chromosomes (Chr), with a marker density of 78.7 kbp. A total of 31 SNPs located on 12 of the 20 soybean chromosomes were correlated with seed protein and oil content. Of the 31 SNPs that were associated with the two target traits, 31 beneficial alleles were identified. Two SNP markers, namely rs15774585 and rs15783346 on Chr 07, were determined to be related to seed oil content both in 2015 and 2016. Three SNP markers, rs53140888 on Chr 01, rs19485676 on Chr 13, and rs24787338 on Chr 20 were correlated with seed protein content both in 2015 and 2016. These beneficial alleles may potentially contribute towards the MAS of favorable soybean protein and oil characteristics.     

Natural variation of GmFATA1B regulates seed oil content and composition in soybean

Soybean (Glycine max) produces seeds that are rich in unsaturated fatty acids and is an important oilseed crop worldwide. Seed oil content and composition largely determine the economic value of soybean. Due to natural genetic variation, seed oil content varies substantially across soybean cultivars. Although much progress has been made in elucidating the genetic trajectory underlying fatty acid metabolism and oil biosynthesis in plants, the causal genes for many quantitative trait loci (QTLs) regulating seed oil content in soybean remain to be revealed. In this study, we identified GmFATA1B as the gene underlying a QTL that regulates seed oil content and composition, as well as seed size in soybean. Nine extra amino acids in the conserved region of GmFATA1B impair its function as a fatty acyl–acyl carrier protein thioesterase, thereby affecting seed oil content and composition. Heterogeneously overexpressing the functional GmFATA1B allele in Arabidopsis thaliana increased both the total oil content and the oleic acid and linoleic acid contents of seeds. Our findings uncover a previously unknown locus underlying variation in seed oil content in soybean and lay the foundation for improving seed oil content and composition in soybean.     

Mapping tightly linked genes controlling potyvirus infection at the Rsv1 and Rpv1 region in soybean.

Soybean mosaic virus (SMV) and peanut mottle virus (PMV) are two potyviruses that cause yield losses and reduce seed quality in infested soybean (Glycine max (L.) Merr.) fields throughout the world. Rsv1 and Rpv1 are genes that provide soybean with resistance to SMV and PMV, respectively. Isolating and characterizing Rsv1 and Rpv1 are instrumental in providing insight into the molecular mechanism of potyvirus recognition in soybean. A population of 1056 F2 individuals from a cross between SMV- and PMV-resistant line PI 96983 (Rsv1 and Rpv1) and the susceptible cultivar 'Lee 68' (rsv1 and rpv1) was used in this study. Disease reaction and molecular-marker data were collected to determine the linkage relationship between Rsv1, Rpv1, and markers that target candidate disease-resistance genes. F2 lines showing a recombination between two of three Rsv1-flanking microsatellite markers were selected for fine mapping. Over 20 RFLP, RAPD, and microsatellite markers were used to map 38 loci at high-resolution to a 6.8-cM region around Rsv1 and Rpv1. This study demonstrates that Rsv1 and Rpv1 are tightly linked at a distance of 1.1 cM. In addition, resistance-gene candidate sequences were mapped to positions flanking and cosegregating with these resistance loci. Based on comparisons of genetic markers and disease reactions, it appears likely that several tightly linked genes are conditioning a resistance response to SMV. We discuss the specifics of these findings and investigate the utility of two disease resistance related probes for the screening of SMV or PMV resistance in soybean.     

Expression of an 11 kDa methionine-rich delta-zein in transgenic soybean results in the formation of two types of novel protein bodies in transitional cells situated between the vascular tissue and storage parenchyma cells

Soybean (Glycine max (L.) Merr.) is an important protein source in human diets and animal feeds. The sulphur content of soybean seed proteins, however, is not optimal for ration formulations. Thus, increasing the methionine and cysteine content of soybean seed proteins would enhance the nutritional quality of this widely utilized legume. We have earlier reported the isolation of an 11 kDa delta-zein protein rich in methionine from the endosperm of the maize (Zea mays L.) inbred line W23a1 [Kim, W.-S. and Krishnan, H.B. (2003) Allelic variation and differential expression of methionine-rich-delta-zeins in maize inbred lines B73 and W23a1. Planta, 217, 66-74]. Using Agrobacterium-mediated transformation, a construct consisting of the coding region of the cloned delta-zein gene under regulation of the beta-conglycinin alpha'-promoter was introduced into the soybean genome. The 11 kDa delta-zein gene was expressed in the seeds of transgenic soybeans, although low-level expression was also detected in the leaves. In situ hybridization indicated that the 11 kDa delta-zein mRNA was expressed predominantly in transitional cells located between the vascular tissue and storage parenchyma cells. Immunohistochemistry of developing transgenic soybeans revealed that the accumulation of the 11 kDa delta-zein occurred primarily in these transitional cells. Expression of the 11 kDa delta-zein gene in transgenic soybean resulted in the formation of two endoplasmic reticulum-derived protein bodies that were designated as either spherical or complex. Immunocytochemical localization demonstrated that both the spherical and complex protein bodies accumulated the 11 kDa delta-zein. Although expression of the 11 kDa delta-zein gene elevated the methionine content of the alcohol-soluble protein fraction 1.5-1.7-fold above that of the non-transgenic line, the overall methionine content of seed flour was not increased. Our results suggest that the confined expression of the 11 kDa delta-zein gene in transitional cells could be limiting the increase in methionine content in transgenic soybean seeds.     

Protein Synthesis During Rehydration, Germination and Seedling Growth of Naturally and Precociously Matured Soybean Seeds (Glycine max)

Soybean seeds [Glycine max (L.) Merr.] synthesize de novo andaccumulate several non-storage, soluble polypeptides duringnatural and precocious seed maturation. These polypeptides havepreviously been coined ‘maturation polypeptides’.The objective of this study was to determine the fate of maturationpolypeptides in naturally and precociously matured soybean seedsduring rehydration, germination, and seedling growth. Developingsoybean seeds harvested 35 d after flowering (mid-development)were precociously matured through controlled dehydration, whereasnaturally matured soybean seeds were harvested directly fromthe plant. Seeds were rehydrated with water for various timesbetween 5 and 120 h. Total soluble proteins and proteins radio-labelledin vivo were extracted from the cotyledons and embryonic axesof precociously and naturally matured and rehydrated seed tissuesand analyzed by one-dimensional PAGE and fluorography. The resultsindicated that three of the maturation polypeptides (21, 31and 128 kDa) that had accumulated in the maturing seeds (maturationpolypeptides) continued to be synthesized during early stagesof seed rehydration and germination (5–30 h after imbibition).However, the progression from seed germination into seedlinggrowth (between 30 and 72 h after imbibition) was marked bythe cessation of synthesis of the maturation polypeptides followedby the hydrolysis of storage polypeptides that had been synthesizedand accumulated during seed development. This implied a drasticredirection in seed metabolism for the precociously maturedseeds as these seeds, if not matured early, would have continuedto synthesize storage protein reserves. Glycine max (L.) Merr, soybean, cotyledons, maturation, germination/seedling growth     

Mapping of the genomic regions controlling seed storability in soybean (Glycine max L.)

Seed storability is especially important in the tropics due to high temperature and relative humidity of storage environment that cause rapid deterioration of seeds in storage. The objective of this study was to use SSR markers to identify genomic regions associated with quantitative trait loci (QTLs) controlling seed storability based on relative germination rate in the F_2:3 population derived from a cross between vegetable soybean line (MJ0004-6) with poor longevity and landrace cultivar from Myanmar (R18500) with good longevity. The F_2:4 seeds harvested in 2011 and 2012 were used to investigate seed storability. The F₂ population was genotyped with 148 markers and the genetic map consisted of 128 SSR loci which converged into 38 linkage groups covering 1664.3 cM of soybean genome. Single marker analysis revealed that 13 markers from six linkage groups (C1, D2, E, F, J and L) were associated with seed storability. Composite interval mapping identified a total of three QTLs on linkage groups C1, F and L with phenotypic variance explained ranging from 8.79 to 13.43%. The R18500 alleles increased seed storability at all of the detected QTLs. No common QTLs were found for storability of seeds harvested in 2011 and 2012. This study agreed with previous reports in other crops that genotype by environment interaction plays an important role in expression of seed storability.     

Genetic control of soybean seed oil: II. QTL and genes that increase oil concentration without decreasing protein or with increased seed yield

Soybean [Glycine max (L.) Merrill] seed oil is the primary global source of edible oil and a major renewable and sustainable feedstock for biodiesel production. Therefore, increasing the relative oil concentration in soybean is desirable; however, that goal is complex due to the quantitative nature of the oil concentration trait and possible effects on major agronomic traits such as seed yield or protein concentration. The objectives of the present study were to study the relationship between seed oil concentration and important agronomic and seed quality traits, including seed yield, 100-seed weight, protein concentration, plant height, and days to maturity, and to identify oil quantitative trait loci (QTL) that are co-localized with the traits evaluated. A population of 203 F_4:6 recombinant inbred lines, derived from a cross between moderately high oil soybean genotypes OAC Wallace and OAC Glencoe, was developed and grown across multiple environments in Ontario, Canada, in 2009 and 2010. Among the 11 QTL associated with seed oil concentration in the population, which were detected using either single-factor ANOVA or multiple QTL mapping methods, the number of QTL that were co-localized with other important traits QTL were six for protein concentration, four for seed yield, two for 100-seed weight, one for days to maturity, and one for plant height. The oil-beneficial allele of the QTL tagged by marker Sat_020 was positively associated with seed protein concentration. The oil favorable alleles of markers Satt001 and GmDGAT2B were positively correlated with seed yield. In addition, significant two-way epistatic interactions, where one of the interacting markers was solely associated with seed oil concentration, were identified for the selected traits in this study. The number of significant epistatic interactions was seven for yield, four for days to maturity, two for 100-seed weight, one for protein concentration, and one for plant height. The identified molecular markers associated with oil-related QTL in this study, which also have positive effects on other important traits such as seed yield and protein concentration, could be used in the soybean marker breeding programs aimed at developing either higher seed yield and oil concentration or higher seed protein and oil concentration per hectare. Alternatively, selecting complementary parents with greater breeding values due to positive epistatic interactions could lead to the development of higher oil soybean cultivars.     

A High-Density Genetic Map for Soybean Based on Specific Length Amplified Fragment Sequencing

Soybean is an important oil seed crop, but very few high-density genetic maps have been published for this species. Specific length amplified fragment sequencing (SLAF-seq) is a recently developed high-resolution strategy for large scale de novo discovery and genotyping of single nucleotide polymorphisms. SLAF-seq was employed in this study to obtain sufficient markers to construct a high-density genetic map for soybean. In total, 33.10 Gb of data containing 171,001,333 paired-end reads were obtained after preprocessing. The average sequencing depth was 42.29 in the Dongnong594, 56.63 in the Charleston, and 3.92 in each progeny. In total, 164,197 high-quality SLAFs were detected, of which 12,577 SLAFs were polymorphic, and 5,308 of the polymorphic markers met the requirements for use in constructing a genetic map. The final map included 5,308 markers on 20 linkage groups and was 2,655.68 cM in length, with an average distance of 0.5 cM between adjacent markers. To our knowledge, this map has the shortest average distance of adjacent markers for soybean. We report here a high-density genetic map for soybean. The map was constructed using a recombinant inbred line population and the SLAF-seq approach, which allowed the efficient development of a large number of polymorphic markers in a short time. Results of this study will not only provide a platform for gene/quantitative trait loci fine mapping, but will also serve as a reference for molecular breeding of soybean.     

Genetic mapping of QTLs conditioning soybean sprout yield and quality

Soybean sprouts have been used as a food in the Orient since ancient times. In this study, 92 restriction fragment length polymorphism (RFLP) loci and two morphological markers (W1 and T) were used to identify quantitative trait loci (QTLs) associated with soybean sprout-related traits in 100 F₂-derived lines from the cross of ’Pureunkong’×’Jinpumkong 2’. The genetic map consisted of 76 loci which covered about 756 cM and converged into 20 linkage groups. Eighteen markers remained unlinked. Phenotypic data were collected in 1996 and 1997 for hypocotyl length, percentage of abnormal seedlings, and sprout yield 6 days after germination at 20°C. Hypocotyl length was determined as the average length from the point of initiation of the first secondary root to the point of attachment of the cotyledons. The number of decayed seeds and seedlings, plus the number of stunted seedlings (less than 2-cm growth), was recorded a s abnormal seedlings. Seed weight was determined based on the 50-seed sample. Sprout yield was recorded as the total fresh weight of soybean sprouts produced from the 50-seed sample divided by the dry weight of the 50-seed sample. Four QTLs were associated with sprout yield in the combined analysis across 2 years. For the QTL linked to L154 on the Linkage Group (LG) G the positive allele was derived from Pureunkong (R ² = 0.19), whereas at the other three QTLs (A089 on LG B1, A668n on LG K and B046 on LG L) the positive alleles were from Jinpumkong 2. QTLs conditioning seed weight were linked to markers A802n (LG B1), A069 (LG E), Cr321 (LG F) and A235 (LG G). At these four markers, the Jinpumkong allele increased seed weight. Markers K011n on LG B1, W1 on LG F and A757 on LG L were linked to QTLs conditioning hypocotyl length; and Bng119, K455n and K418n to QTLs conditioning the abnormal seedlings. The QTLs conditioning sprout yield were in the same genomic locations as the QTLs for seed weight identified in this population or from previously published research, indicating that QTLs for sprout yield are genetically linked to seed-weight QTLs or else that seed-weight QTLs pleiotropically condition sprout yield. These data demonstrate that effective marker-assisted selection may be feasible for enhancing sprout yield in a soybean. The transgressive segregation of sprout yield, as well as the existence of two QTLs conditioning greater than 10% of the phenotypic variation in sprout yields provides an opportunity to select for progeny lines with a greater sprout yield than currently preferred cultivars such as Pureunkong. Received: 23 August 2000 / Accepted: 23 January 2001     

Accumulation of high levels of free amino acids in soybean seeds through integration of mutations conferring seed protein deficiency

Soybean ( Glycine max [L.] Merr.) seeds are rich in protein, most of which is contributed by the major storage proteins glycinin (11S globulin) and beta-conglycinin (7S globulin). Null mutations for each of the subunits of these storage proteins were integrated by crossbreeding to yield a soybean line that lacks both glycinin and beta-conglycinin components. In spite of the absence of these two major storage proteins, the mutant line grew and reproduced normally, and the nitrogen content of its dry seed was similar to that for wild-type cultivars. However, protein bodies appeared underdeveloped in the cotyledons of the integrated mutant line. Furthermore, whereas free amino acids contribute only 0.3-0.8% of the seed nitrogen content of wild-type varieties, they constituted 4.5-8.2% of the seed nitrogen content in the integrated mutant line, with arginine (Arg) being especially enriched in the mutant seeds. Seeds of the integrated mutant line thus appeared to compensate for the reduced nitrogen content in the form of glycinin and beta-conglycinin by accumulating free amino acids as well as by increasing the expression of certain other seed proteins. These results indicate that soybean seeds are able to store nitrogen mostly in the form of either proteins or free amino acids.     

Simple sequence repeat (SSR) markers linked to E1, E3, E4, and E7 maturity genes in soybean.

Soybean near isogenic lines (NILs), contrasting for maturity and photoperiod sensitivity loci, were genotyped with approximately 430 mapped simple sequence repeats (SSRs), also known as microsatellite markers. By analysis of allele distributions across the NILs, it was possible to confirm the map location of the Dt1 indeterminate growth locus, to refine the SSR mapping of the T tawny pubescence locus, to map E1 and E3 maturity loci with molecular markers, and to map the E4 and E7 maturity loci for the first time. Molecular markers flanking these loci are now available for marker-assisted breeding for these traits. Analysis of map locations identified a putative homologous relationship among four chromosomal regions; one in the middle of linkage group (LG) C2 carrying E1 and E7, one on LG I carrying E4, one at the top of LG C2, at which there is a reproductive period quantitative trait locus (QTL), and the fourth on LG B1. Other evidence suggests that homology also exists between the E1 + E7 region on LG C2 and a region on LG L linked to a pod maturity QTL. Homology relationships predict possible locations in the soybean genome of additional maturity loci, as well as which maturity loci may share a common evolutionary origin and similar mechanism(s) of action.     

Identification of germplasm with stacked QTL underlying seed traits in an inbred soybean population from cultivars Essex and Forrest

Soybean (Glycine max (L.) Merr.) seed provides valuable oil (~200 g/kg) and protein (~400 g/kg) co-products. Seed composition variations result from several quantitative trait loci (QTL) that act through development. The objectives here were to identify loci underlying seed traits in the Essex × Forrest (EF94)-derived recombinant inbred line (RIL) population which has low frequencies of marker polymorphisms. Seed weight, protein, and oil were measured over 3 years: 2001, 2003, and 2005. Essex’s seeds were larger (141 mg/seed), higher in protein (406 g/kg), and lower in oil (190 g/kg) than Forrest’s (115 mg/seed, 395 g protein/kg, and 203 g oil/kg). Marker analysis included 413 markers for trait associations used for ANOVA, interval mapping, and composite interval mapping. Eleven QTL in nine genomic regions were associated (LOD >2; P < 0.0077) with seed traits. Two QTL, for mean protein and seed size, were clustered on linkage group (LG) E (chromosome Gm16). QTL for protein content alone were found on LG C2 (Gm6), LG D1b (Gm2), LG H (Gm12), and LG I (Gm20). The alleles from Essex, the high-protein parent, underlay higher protein (4–10 g/kg) at four of five loci. A QTL for mean oil was found on LG A2 (Gm18) and on LG I (Gm 20). The alleles from Forrest underlay higher oil (3–4 g/kg). Five separate QTL for mean seed weight were found on LG A1 (Gm05), LG N (Gm15), two on LG B1 (Gm11) and one on LG N (Gm3). The alleles from Essex underlay greater seed weight (0.4–0.66 g/100 seeds). The QTL positions were consistent with reported loci. Germplasm that contained all five beneficial alleles at the QTL underlying protein was significantly higher in protein and yield than Essex (409.7–412.3 g/kg) and included RILs 49 and 62. The germplasm identified can be useful for further breeding of the many traits and QTL measured in each line.     

Role of Lectins in Plant-Microorganism Interactions: II. Distribution of Soybean Lectin in Tissues of Glycine max (L.) Merr

Three different assay procedures have been used to quantitate the levels of soybean (Glycine max [L.] Merr.) lectin in various tissues of soybean plants. The assays used were a standard hemagglutination assay, a radioimmunoassay, and an isotope dilution assay. Most of the lectin in seeds was found in the cotyledons, but lectin was also detected in the embryo axis and the seed coat. Soybean lectin was present in all of the tissues of young seedlings, but decreased as the plants matured and was not detectable in plants older than 2 to 3 weeks. Soybean lectin isolated from seeds of several soybean varieties were identical when compared by several methods.