A sucrose-binding protein and ß-conglycinins regulate soybean seed protein content and control multiple seed traits.

Expanded agriculture production is required to support the world's population but can impose substantial environmental and climate change costs, particularly with intensifying animal production and protein demand. Shifting from an animal- to a plant-based protein diet has numerous health benefits. Soybean (Glycine max [L.] Merr.) is a major source of protein for human food and animal feed; improved soybean protein content and amino acid composition could provide high-quality soymeal for animal feed, healthier human foods, and a reduced carbon footprint. Nonetheless, during the soybean genome evolution, a balance was established between the amount of seed protein, oil, and carbohydrate content, burdening the development of soybean cultivars with high proteins (HPs). We isolated 2 high-seed protein soybean mutants, HP1 and HP2, with improved seed amino acid composition and stachyose content, pointing to their involvement in controlling seed rebalancing phenomenon. HP1 encodes ß-conglycinin (GmCG-1) and HP2 encodes sucrose-binding protein (GmSBP-1), which are both highly expressed in soybean seeds. Mutations in GmSBP-1, GmCG-1, and the paralog GmCG-2 resulted in increased protein levels, confirming their role as general regulators of seed protein content, amino acid seed composition, and seed vigor. Biodiversity analysis of GmCG and GmSBP across 108 soybean accessions revealed haplotypes correlated with protein and seed carbohydrate content. Furthermore, our data revealed an unprecedented role of GmCG and GmSBP proteins in improving seed vigor, crude protein, and amino acid digestibility. Since GmSBP and GmCG are present in most seed plants analyzed, these genes could be targeted to improve multiple seed traits.

Cover Crop and Crop Rotation Effects on Tissue and Soil Population Dynamics of Macrophomina phaseolina and Yield Under No-Till System.

The effects of crop rotation and winter cover crops on soybean yield and colony-forming (CFU) units of Macrophomina phaseolina, the causal agent of charcoal rot (CR), are poorly understood. A field trial was conducted from 2011 to 2015 to evaluate (i) the impact of crop rotation consisting of soybean (Glycine max [L.] Merr.) following cotton (Gossypium hirsutum L.), soybean following corn (Zea mays L.), and soybean following soybean over a 2-year rotation and its interaction with cover crop and (ii) the impact of different cover crops on a continuous soybean crop over a 5-year period. This trial was conducted in a field with 10 subsequent years of cover crop and rotation treatments. Cover crops consisted of winter wheat (Triticum aestivum L.) and Austrian winter pea (Pisum sativum L. subsp. sativum var. arvense), hairy vetch (Vicia villosa Roth), and a fallow treatment was evaluated with and without poultry litter application (bio-cover). Tissue CFU of M. phaseolina varied significantly between crop rotation treatments: plots where soybean was grown following cotton had significantly greater tissue CFU than plots following soybean. Poultry litter and hairy vetch cover cropping caused increased tissue CFU, though this effect differed by year and crop rotation treatment. Soil CFU in 2015 was substantially lower compared with 2011. However, under some crop rotation sequences, plots in the fallow treatment had significantly greater soil CFU than plots where hairy vetch and wheat was grown as a cover crop. Yield was greater in 2015 compared with 2011. There was a significant interaction of the previous crop in the rotation with year, and greater yield was observed in plots planted following cotton in the rotation in 2015 but not in 2011. The result from the continuous soybean planted over 5 years showed that there were no significant overall effects of any of the cover crop treatments nor was there interaction between cover crop treatment and year on yield. The lack of significant interaction between crop rotation and cover crop and the absence of significant differences between cover crop treatments in continuous soybean planting suggest that cover crop recommendations for midsouthern soybean growers may need to be independent of crop rotation and be based on long-term crop needs.

Charcoal Rot Severity and Soybean Yield Responses to Planting Date, Irrigation, and Genotypes.

Soybean (Glycine max [L.] Merr.) production is influenced by planting date, but its impact on yield in fields infested with Macrophomina phaseolina (Tassi) Goid. is unknown. A 3-year study was conducted in M. phaseolina-infested fields to assess the effects of planting date (PD) on disease severity and yield using eight genotypes, four of which are reported to be susceptible to charcoal rot (S), and four reported with moderate resistance (MR) to charcoal rot (CR). The genotypes were planted in early April, early May, and early June under irrigated and nonirrigated conditions. There was planting date by irrigation interaction for area under the disease progress curve (AUDPC) where May PD was significantly lower compared to April and June PDs in irrigated environments but not in nonirrigated environments. Correspondingly, yield in April PD was significantly lower than that of May and June. Interestingly, yield of S genotypes increased significantly with each subsequent PD, while yield of MR genotypes remained high across all three PDs. The interaction of genotypes by PD on yield revealed that the MR genotypes DT97-4290 and DS-880 had the greatest yields in May compared to April. While May PD had a decreased AUDPC and an increased yield across genotypes, the result of this research suggests that in fields infested with M. phaseolina, early May to early June planting coupled with appropriate cultivar selection provides maximum yield potential for western Tennessee and mid-southern soybean growers.

Field studies on the deterioration of microplastic films from ultra-thin compostable bags in soil.

In recent years, some countries have replaced single-use plastic bags with bags manufactured from compostable plastic film that can be used for collecting food wastes and composted together with the waste. Because industrial compost contains undeteriorated fragments of these bags, application to field soil is a potential source of small-sized residues from these bags. This study was undertaken to examine deterioration of these compostable film microplastics (CFMPs) in field soil at three different localities in Italy. Deterioration of CFMPs did not exceed 5.7% surface area reduction during the 12-month experimental period in two sites located in Northern Italy. More deterioration was observed in the Southern site, with 7.2% surface area reduction. Deterioration was significantly increased when fields were amended with industrial compost (up to 9.6%), but not with home compost. Up to 92.9% of the recovered CFMPs were associated with the soil fungus Aspergillus flavus, with 20.1%-71.2% aflatoxin-producing isolates. Application of industrial compost resulted in a significant increase in the percentage of CFMPs associated with A. flavus. This observation provides an argument for government regulation of accumulation of CFMPs and elevation of hazardous fungi levels in agricultural soils that receive industrial compost.

Pathotype Grouping of Cercospora sojina Isolates on Soybean and Sensitivity to QoI Fungicides.

Frogeye leaf spot (FLS), caused by Cercospora sojina, is a common disease of soybean in the southern and northern United States and causes significant yield loss. The use of the current race scheme for classification for C. sojina does not take into account the range of disease severity reactions within each differential. The objective of this research was to better understand the diversity among C. sojina isolates through the development and use of pathogenicity groups. In this study, 83 isolates acquired from 2006 to 2009 were screened using 12 soybean (Glycine max) differentials. Disease severity on the 12 differentials ranged from 0 to 9, where 0 is immune and 9 is very susceptible. The average severity for each isolate across differentials ranged from 1 to 7. The 83 isolates were grouped into five pathogenicity groups (PG): PG1, PG2, PG3, PG4, and PG5, reflecting the severity grouping. Using the 12 differentials, PG1 isolates were differentiated by the lack of infection on Davis, Peking, Kent, Palmetto, Hood, CNS, Tracy, and Richland. PG2 had a range of infections on a scale of 1 to 2 on all differentials except on Davis; PG3 isolates had severity ranging from 3 to 4 except on Davis. PG4 isolates caused no infection on Davis, a maximum disease severity of 5 on Peking, while the rest of differentials had severities from 5 to 6. PG5 isolates caused no infection on Davis, severity of 7 on CNS, and severity of 8 on Kent, Hood, and Palmetto. The remaining seven differentials had severities of 9. Across the geographical locations, the predominant pathotypes were PG3 and PG4 and represented 84% of the tested isolates. Azoxystrobin fungicide sensitivity tests showed that 88% of the isolates were sensitive and dominated the population, while only 6% had a high level of fungicide resistance, suggesting that FLS resistance to the QoI fungicide group was not yet completely developed and had not spread to other areas at the time when these isolates were acquired. The overall virulence profile of the isolates indicated that there was variation in disease severity, suggesting that selection of resistance for each PG may produce lines with more precisely defined interactions to specific pathotypes of C. sojina. This may improve the screening and selection of useful resistance genes that could be pyramided for resistance to each pathogenicity group.

Effects of boron nutrition and water stress on nitrogen fixation, seed δ15N and δ13C dynamics, and seed composition in soybean cultivars differing in maturities.

Therefore, the objective of the current research was to investigate the effects of foliar B nutrition on seed protein, oil, fatty acids, and sugars under water stress conditions. A repeated greenhouse experiment was conducted using different maturity group (MG) cultivars. Plants were well-watered with no foliar B (W - B), well-watered with foliar B (W + B), water-stressed with no foliar B (WS - B), and water-stressed with foliar B (WS + B). Foliar B was applied at rate of 0.45 kg · ha(-1) and was applied twice at flowering and at seed-fill stages. The results showed that seed protein, sucrose, fructose, and glucose were higher in W + B treatment than in W - B, WS + B, and WS - B. The increase in protein in W + B resulted in lower seed oil, and the increase of oleic in WS - B or WS + B resulted in lower linolenic acid. Foliar B resulted in higher nitrogen fixation and water stress resulted in seed δ (15)N and δ (13)C alteration. Increased stachyose indicated possible physiological and metabolic changes in carbon and nitrogen pathways and their sources under water stress. This research is beneficial to growers for fertilizer management and seed quality and to breeders to use (15)N/(14)N and (13)C/(12)C ratios and stachyose to select for drought tolerance soybean.

Tillage, Fungicide, and Cultivar Effects on Frogeye Leaf Spot Severity and Yield in Soybean.

Frogeye leaf spot (FLS) of soybean, caused by Cercospora sojina, has been a problem in the southern United States for many years but has become an increasing problem in the northern United States more recently, causing significant yield losses. This increase in disease severity in the northern United States has been attributed to increased utilization of no-till planting and changes in climate. A field study was conducted at the University of Tennessee, Research and Education Center in Milan, TN from 2007 to 2010 to determine severity in tilled and no-till plots treated with or without fungicide at R3 and R5 growth stages. Three FLS-susceptible cultivars, one each in Maturity Groups III, IV, and V, were treated with pyraclostrobin (Headline) fungicide. Analysis of variance using the area under the disease progress curve (AUDPC) indicated no significant difference (P ≤ 0.05) in disease severity between tilled and no-till plots without fungicide. Fungicide did not significantly reduce disease under no-till, but did under tilled plots. This is the first study showing that no-till plots did not reduce or enhance the severity of FLS when no fungicide was applied. Fungicide application significantly reduced (P ≤ 0.05) disease severity and AUDPC and increased yield in tilled plots. The yield gains in tilled, fungicide-treated plots ranged from 1 to 17%. When fungicide was applied, disease severity was not reduced as significantly in no-till as in treated tilled plots, suggesting that fungicide programs under a no-till system may require further study to minimize the risk of FLS severity.

Soybean Seed Sugars: A Role in the Mechanism of Resistance to Charcoal Rot and Potential Use as Biomarkers in Selection.

Charcoal rot, caused by Macrophomina phaseolina, is a major soybean disease resulting in significant yield loss and poor seed quality. Currently, no resistant soybean cultivar is available in the market and resistance mechanisms to charcoal rot are unknown, although the disease is believed to infect plants from infected soil through the roots by unknown toxin-mediated mechanisms. The objective of this research was to investigate the association between seed sugars (sucrose, raffinose, stachyose, glucose, and fructose) and their role as biomarkers in the soybean defense mechanism in the moderately resistant (MR) and susceptible (S) genotypes to charcoal rot. Seven MR and six S genotypes were grown under irrigated (IR) and non-irrigated (NIR) conditions. A two-year field experiment was conducted in 2012 and 2013 at Jackson, TN, USA. The main findings in this research were that MR genotypes generally had the ability to maintain higher seed levels of sucrose, glucose, and fructose than did S genotypes. Conversely, susceptible genotypes showed a higher level of stachyose and lower levels of sucrose, glucose, and fructose. This was observed in 6 out of 7 MR genotypes and in 4 out of 6 S genotypes in 2012; and in 5 out of 7 MR genotypes and in 5 out of 6 S genotypes in 2013. The response of S genotypes with higher levels of stachyose and lower sucrose, glucose, and fructose, compared with those of MR genotypes, may indicate the possible role of these sugars in a defense mechanism against charcoal rot. It also indicates that nutrient pathways in MR genotypes allowed for a higher influx of nutritious sugars (sucrose, glucose, and fructose) than did S genotypes, suggesting these sugars as potential biomarkers for selecting MR soybean plants after harvest. This research provides new knowledge on seed sugars and helps in understanding the impact of charcoal rot on seed sugars in moderately resistant and susceptible genotypes.

Quantitative Trait Loci and Candidate Genes That Control Seed Sugars Contents in the Soybean 'Forrest' by 'Williams 82' Recombinant Inbred Line Population.

Soybean seed sugars are among the most abundant beneficial compounds for human and animal consumption in soybean seeds. Higher seed sugars such as sucrose are desirable as they contribute to taste and flavor in soy-based food. Therefore, the objectives of this study were to use the 'Forrest' by 'Williams 82' (F × W82) recombinant inbred line (RIL) soybean population (n = 309) to identify quantitative trait loci (QTLs) and candidate genes that control seed sugar (sucrose, stachyose, and raffinose) contents in two environments (North Carolina and Illinois) over two years (2018 and 2020). A total of 26 QTLs that control seed sugar contents were identified and mapped on 16 soybean chromosomes (chrs.). Interestingly, five QTL regions were identified in both locations, Illinois and North Carolina, in this study on chrs. 2, 5, 13, 17, and 20. Amongst 57 candidate genes identified in this study, 16 were located within 10 Megabase (MB) of the identified QTLs. Amongst them, a cluster of four genes involved in the sugars' pathway was collocated within 6 MB of two QTLs that were detected in this study on chr. 17. Further functional validation of the identified genes could be beneficial in breeding programs to produce soybean lines with high beneficial sucrose and low raffinose family oligosaccharides.

Genetic Mapping for QTL Associated with Seed Nickel and Molybdenum Accumulation in the Soybean 'Forrest' by 'Williams 82' RIL Population.

Understanding the genetic basis of seed Ni and Mo is essential. Since soybean is a major crop in the world and a major source for nutrients, including Ni and Mo, the objective of the current research was to map genetic regions (quantitative trait loci, QTL) linked to Ni and Mo concentrations in soybean seed. A recombinant inbred line (RIL) population was derived from a cross between 'Forrest' and 'Williams 82' (F × W82). A total of 306 lines was used for genotyping using 5405 single nucleotides polymorphism (SNP) markers using Infinium SNP6K BeadChips. A two-year experiment was conducted and included the parents and the RIL population. One experiment was conducted in 2018 in North Carolina (NC), and the second experiment was conducted in Illinois in 2020 (IL). Logarithm of the odds (LOD) of ≥2.5 was set as a threshold to report identified QTL using the composite interval mapping (CIM) method. A wide range of Ni and Mo concentrations among RILs was observed. A total of four QTL (qNi-01, qNi-02, and qNi-03 on Chr 2, 8, and 9, respectively, in 2018, and qNi-01 on Chr 20 in 2020) was identified for seed Ni. All these QTL were significantly (LOD threshold > 2.5) associated with seed Ni, with LOD scores ranging between 2.71-3.44, and with phenotypic variance ranging from 4.48-6.97%. A total of three QTL for Mo (qMo-01, qMo-02, and qMo-03 on Chr 1, 3, 17, respectively) was identified in 2018, and four QTL (qMo-01, qMo-02, qMo-03, and qMo-04, on Chr 5, 11, 14, and 16, respectively) were identified in 2020. Some of the current QTL had high LOD and significantly contributed to the phenotypic variance for the trait. For example, in 2018, Mo QTL qMo-01 on Chr 1 had LOD of 7.8, explaining a phenotypic variance of 41.17%, and qMo-03 on Chr 17 had LOD of 5.33, with phenotypic variance explained of 41.49%. In addition, one Mo QTL (qMo-03 on Chr 14) had LOD of 9.77, explaining 51.57% of phenotypic variance related to the trait, and another Mo QTL (qMo-04 on Chr 16) had LOD of 7.62 and explained 49.95% of phenotypic variance. None of the QTL identified here were identified twice across locations/years. Based on a search of the available literature and of SoyBase, the four QTL for Ni, identified on Chr 2, 8, 9, and 20, and the five QTL associated with Mo, identified on Chr 1, 17, 11, 14, and 16, are novel and not previously reported. This research contributes new insights into the genetic mapping of Ni and Mo, and provides valuable QTL and molecular markers that can potentially assist in selecting Ni and Mo levels in soybean seeds.

Influence of Curly Leaf Trait on Cottonseed Micro-Nutrient Status in Cotton (Gossypium hirsutum L.) Lines.

Cottonseed is a source of nutrients, including protein, oil, and macro- and micro-nutrients. Micro-nutrients such as boron (B), copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn) are essential for plant and human health. Deficiencies of these micro-nutrients in soil lead to poor crop production and poor seed quality. Micro-nutrient deficiencies in the human diet lead to malnutrition and serious health issues. Therefore, identifying new cotton lines containing high nutritional qualities such as micro-nutrients, and understanding plant traits influencing micro-nutrients are essential. The objective of this research was to investigate the effects of leaf shape (curly leaf: CRL) on cottonseed B, Cu, Fe, Mn, Ni (nickel), and Zn in two near-isogenic cotton lines differing in leaf shape (DP 5690 wild-type with normal leaves and DP 5690 CRL). We also used Uzbek CRL, the source of the curly leaf trait, for comparison. A field experiment was conducted in 2014 and 2015 in Stoneville, MS, USA. The experiment was a randomized complete block design with three replicates. The results showed that, in 2014, both DP 5690 wild-type and Uzbek CRL had higher seed B, Cu, Fe, and Ni than in DP 5690 CRL. The accumulation of Mn and Zn in seeds of DP 5690 CRL was higher than in DP 5690 wild-type and Uzbek CRL. However, in 2015, the concentrations of B, Cu, Fe, and Ni, including Mn and Zn, were higher in both DP 5690 wild-type and Uzbek CRL than in DP 5690 CRL. Positive and negative correlations existed in 2014; however, only positive correlations existed between all nutrients in 2015. This research demonstrated that leaf shape can alter cottonseed micro-nutrients status. As Uzbek CRL behaved similar to wild-type, both leaf shape and other factors contributed to the alteration in seed micronutrients, affecting seed nutritional qualities. Therefore, leaf-shape partially contributed to the changes in micro-nutrients in cottonseed. The negative and positive correlations in 2014, and only positive correlations in 2015, were likely due to the heat difference between 2014 and 2015 as 2015 was warmer than 2014. Significant levels of seed micro-nutrients were shown between these lines, providing opportunities for breeders to select for high seed micro-nutrients in cotton. Additionally, the current research provides researchers with physiological information on the impact of leaf shape on seed nutritional quality. The leaf shape trait can also be used as a tool to study leaf development, physiological, biochemical, and morphological processes.

Cottonseed Protein, Oil, and Minerals in Cotton (Gossypium hirsutum L.) Lines Differing in Curly Leaf Morphology.

Cottonseed is an important source of protein, oil, and minerals for human health and livestock feed. Therefore, understanding the physiological and genetic traits influencing the nutrient content is critical. To our knowledge, there is no information available on the effects of leaf shape-curly leaf (CRL)-on cottonseed protein, oil, and minerals. Therefore, the objective of the current research was to investigate the effect of the curly leaf trait on cottonseed protein, oil, and minerals in cotton lines differing in leaf shape. Our hypothesis was that since leaf shape is known to be associated with nutrient uptake, assimilation, and photosynthesis process, leaf shape can influence seed protein, oil, and minerals. A two-year field experiment using two curly leaf lines (Uzbek CRL and DP 5690 CRL) and one normal leaf (DP 5690 wild type) line was conducted in 2014 and 2015 in Stoneville, MS, USA. The experiment was a randomized complete block design with three replicates. The results showed that both Uzbek CRL and DP 5690 wild type lines had higher seed oil, and nutrients N, P, K, and Mg than DP 5690 CRL. Calcium was higher in DP 5690 CRL for two years and protein was only higher than the parents in 2015. Consistent significant positive and negative correlations between some nutrients were observed, which may be due to environmental conditions, especially heat. This indicates that curly leaf trait may partially regulate the accumulation of these nutrients in seeds. The results demonstrated that leaf shape trait-curly leaf-can affect cottonseed nutritional qualities. This research is important to breeders for cotton selection for high seed oil or protein, and to other researchers to further understand the genetic impact of leaf shapes on seed nutritional quality. It is also important for scientists to use leaf shape as a tool for physiological, biochemical, and morphological research related to leaf development.

Effects of Charcoal Rot on Soybean Seed Composition in Soybean Genotypes That Differ in Charcoal Rot Resistance under Irrigated and Non-Irrigated Conditions.

Charcoal rot is a major disease of soybean (Glycine max) caused by Macrophomina phaseolina and results in significant loss in yield and seed quality. The effects of charcoal rot on seed composition (seed protein, oil, and fatty acids), a component of seed quality, is not well understood. Therefore, the objective of this research was to investigate the impact of charcoal rot on seed protein, oil, and fatty acids in different soybean genotypes differing in their charcoal rot susceptibility under irrigated and non-irrigated conditions. Two field experiments were conducted in 2012 and 2013 in Jackson, TN, USA. Thirteen genotypes differing in charcoal rot resistance (moderately resistant and susceptible) were evaluated. Under non-irrigated conditions, moderately resistant genotypes showed either no change or increased protein and oleic acid but had lower linolenic acid. Under non-irrigated conditions, most of the susceptible genotypes showed lower protein and linolenic acid but higher oleic acid. Most of the moderately resistant genotypes had higher protein than susceptible genotypes under irrigated and non-irrigated conditions but lower oil than susceptible genotypes. The different responses among genotypes for protein, oil, oleic acid, and linolenic acid observed in each year may be due to both genotype tolerance to drought and environmental conditions, especially heat differences in each year (2012 was warmer than 2013). This research showed that the increases in protein and oleic acid and the decrease in linolenic acid may be a possible physiological mechanism underlying the plant's responses to the charcoal rot infection. This research further helps scientists understand the impact of irrigated and non-irrigated conditions on seed nutrition changes, using resistant and susceptible genotypes.

Effects of Interspecific Chromosome Substitution in Upland Cotton on Cottonseed Macronutrients.

Nutrients, including macronutrients such as Ca, P, K, and Mg, are essential for crop production and seed quality, and for human and animal nutrition and health. Macronutrient deficiencies in soil lead to poor crop nutritional qualities and a low level of macronutrients in cottonseed meal-based products, leading to malnutrition. Therefore, the discovery of novel germplasm with a high level of macronutrients or significant variability in the macronutrient content of crop seeds is critical. To our knowledge, there is no information available on the effects of chromosome or chromosome arm substitution on cottonseed macronutrient content. The objective of this study was to evaluate the effects of chromosome or chromosome arm substitution on the variability and content of the cottonseed macronutrients Ca, K, Mg, N, P, and S in chromosome substitution lines (CS). Nine chromosome substitution lines were grown in two-field experiments at two locations in 2013 in South Carolina, USA, and in 2014 in Mississippi, USA. The controls used were TM-1, the recurrent parent of the CS line, and the cultivar AM UA48. The results showed major variability in macronutrients among CS lines and between CS lines and controls. For example, in South Carolina, the mean values showed that five CS lines (CS-T02, CS-T04, CS-T08sh, CS-B02, and CS-B04) had higher Ca level in seed than controls. Ca levels in these CS lines varied from 1.88 to 2.63 g kg-1 compared with 1.81 and 1.72 g kg-1 for TM-1 and AMUA48, respectively, with CS-T04 having the highest Ca concentration. CS-M08sh exhibited the highest K concentration (14.50 g kg-1), an increase of 29% and 49% over TM-1 and AM UA48, respectively. Other CS lines had higher Mg, P, and S than the controls. A similar trend was found at the MS location. This research demonstrated that chromosome substitution resulted in higher seed macronutrients in some CS lines, and these CS lines with a higher content of macronutrients can be used as a genetic tool towards the identification of desired seed nutrition traits. Also, the CS lines with higher desired macronutrients can be used as parents to breed for improved nutritional quality in Upland cotton, Gossypium hirsutum L., through improvement by the interspecific introgression of desired seed nutrient traits such as Ca, K, P, S, and N. The positive and significant (p ≤ 0.0001) correlation of P with Ca, P with Mg, S with P, and S with N will aid in understanding the relationships between nutrients to improve the fertilizer management program and maintain higher cottonseed nutrient content.

The Soybean High Density 'Forrest' by 'Williams 82' SNP-Based Genetic Linkage Map Identifies QTL and Candidate Genes for Seed Isoflavone Content.

Isoflavones are secondary metabolites that are abundant in soybean and other legume seeds providing health and nutrition benefits for both humans and animals. The objectives of this study were to construct a single nucleotide polymorphism (SNP)-based genetic linkage map using the 'Forrest' by 'Williams 82' (F×W82) recombinant inbred line (RIL) population (n = 306); map quantitative trait loci (QTL) for seed daidzein, genistein, glycitein, and total isoflavone contents in two environments over two years (NC-2018 and IL-2020); identify candidate genes for seed isoflavone. The FXW82 SNP-based map was composed of 2075 SNPs and covered 4029.9 cM. A total of 27 QTL that control various seed isoflavone traits have been identified and mapped on chromosomes (Chrs.) 2, 4, 5, 6, 10, 12, 15, 19, and 20 in both NC-2018 (13 QTL) and IL-2020 (14 QTL). The six QTL regions on Chrs. 2, 4, 5, 12, 15, and 19 are novel regions while the other 21 QTL have been identified by other studies using different biparental mapping populations or genome-wide association studies (GWAS). A total of 130 candidate genes involved in isoflavone biosynthetic pathways have been identified on all 20 Chrs. And among them 16 have been identified and located within or close to the QTL identified in this study. Moreover, transcripts from four genes (Glyma.10G058200, Glyma.06G143000, Glyma.06G137100, and Glyma.06G137300) were highly abundant in Forrest and Williams 82 seeds. The identified QTL and four candidate genes will be useful in breeding programs to develop soybean cultivars with high beneficial isoflavone contents.

The Influence of Agricultural Practices, the Environment, and Cultivar Differences on Soybean Seed Protein, Oil, Sugars, and Amino Acids.

Information on the effects of agricultural practices such as seeding rate (S), row spacing (RS), herbicide apical treatment (T), and nitrogen application (N) on soybean seed nutrition (protein, oil, fatty acids, sugars, and amino acids) is limited. Although seed composition (nutrition) constituents are genetically controlled, agricultural practices and environmental conditions significantly influence the amount and quality of seed nutrition. Therefore, the objective of this research was to understand the responses of these seed composition constituents to these practices, the environment, and cultivar differences. Two-field experiments were conducted, in 2015 and 2016, in Milan, TN, USA. The experiments were irrigated with four replications and included: two soybean cultivars, two seeding rates, three different row spacings, two N rates, and Cobra herbicide apical treatment. The results showed significant effects of S, RS, N, and T on some seed composition constituents, including protein; oleic, linolenic, and stearic acids; sugars; and some amino acids. The current research demonstrated that single or twin row with a seeding rate of 40,000 seeds ha-1 resulted in higher protein, oleic, some sugars, and some amino acids. However, a high seeding rate of 56,000 seeds ha-1 resulted in lower protein, oleic acid, some sugars, and some amino acids due to plant competition for soil nutrients. Herbicide apical application of Cobra1X resulted in higher linolenic acid and some amino acids. Application of nitrogen resulted in higher protein, linolenic, and some amino acids. This research is beneficial to the scientific communities, including breeders and physiologists through advancing knowledge on the interactions between cultivars and environment for seed nutritional quality selection, and to soybean producers through consideration of best agricultural management to maintain high seed nutritional qualities.

Effects of Harvest-Aids on Seed Nutrition in Soybean under Midsouth USA Conditions.

Interest in using harvest aids (defoliants or crop desiccants) such as paraquat, carfentrazone-ethyl, glyphosate, and sodium chlorate (NaClO3) have become increasingly important to assure harvest efficiency, producer profit, and to maintain seed quality. However, information on the effects of harvest aids on seed nutrition (composition) (protein, oil, fatty acids, sugars, and amino acids) in soybean is very limited. The objective of this research was to investigate the influence of harvest aids on seed protein, oil, fatty acids, sugars, and amino acids in soybean. Our hypothesis was that harvest aid may influence seed nutrition, especially at R6 as at R6 the seeds may still undergo biochemical changes. Field experiments were conducted in 2012 and 2013 under Midsouth USA environmental conditions in which harvest aids were applied at R6 (seed-fill) and R7 (yellow pods) growth stages. Harvest aids applied included an untreated control, 0.28 kg ai ha-1 of paraquat, 0.28 kg ai ha-1 of paraquat, and 1.015 kg ai ha-1 of carfentrazone-ethyl (AIM); 6.72 kg ai ha-1 sodium chlorate, 1.015 kg ai ha-1 carfentrazone-ethyl; and 2.0 kg ae ha-1 glyphosate. Results showed that the application of harvest aids at either R6 or R7 resulted in the alteration of some seed composition such as protein, oil, oleic acid, fructose, and little effects on amino acids. In addition, harvest aids affected seed composition constituents differently depending on year and growth stage. This research demonstrated the possible alteration of some nutrients by harvest aids. This research helps growers and scientists to advance the understanding and management of harvest aids and investigate possible effects of harvest aids on seed nutrition.

Phytotoxic Responses of Soybean (Glycine max L.) to Botryodiplodin, a Toxin Produced by the Charcoal Rot Disease Fungus, Macrophomina phaseolina.

Toxins have been proposed to facilitate fungal root infection by creating regions of readily-penetrated necrotic tissue when applied externally to intact roots. Isolates of the charcoal rot disease fungus, Macrophomina phaseolina, from soybean plants in Mississippi produced a phytotoxic toxin, (-)-botryodiplodin, but no detectable phaseolinone, a toxin previously proposed to play a role in the root infection mechanism. This study was undertaken to determine if (-)-botryodiplodin induces toxic responses of the types that could facilitate root infection. (±)-Botryodiplodin prepared by chemical synthesis caused phytotoxic effects identical to those observed with (-)-botryodiplodin preparations from M. phaseolina culture filtrates, consistent with fungus-induced phytotoxicity being due to (-)-botryodiplodin, not phaseolinone or other unknown impurities. Soybean leaf disc cultures of Saline cultivar were more susceptible to (±)-botryodiplodin phytotoxicity than were cultures of two charcoal rot-resistant genotypes, DS97-84-1 and DT97-4290. (±)-Botryodiplodin caused similar phytotoxicity in actively growing duckweed (Lemna pausicostata) plantlet cultures, but at much lower concentrations. In soybean seedlings growing in hydroponic culture, (±)-botryodiplodin added to culture medium inhibited lateral and tap root growth, and caused loss of root caps and normal root tip cellular structure. Thus, botryodiplodin applied externally to undisturbed soybean roots induced phytotoxic responses of types expected to facilitate fungal root infection.

Persistence in soil of microplastic films from ultra-thin compostable plastic bags and implications on soil Aspergillus flavus population.

An increasing number of states and municipalities are choosing to reduce plastic litter by replacing plastic items, particularly single-use ones, with same-use products manufactured from compostable plastics. This study investigated the formation and persistence of compostable film microplastic particles (CFMPs) from ultra-thin compostable carrier bags in soil under laboratory conditions, and the potential impact of CFMPs on Aspergillus flavus populations in the soil. During a 12-month incubation period, compostable film samples in soils with small, medium or large populations of indigenous A. flavus, underwent 5.9, 9.8, and 17.1% reduction in total surface area, respectively. Despite the low levels of deterioration, the number of CFMPs released increased steadily over the incubation period, particularly fragments with size < 0.05 mm. Up to 88.4% of the released fragments had associated A. flavus and up to 68% of isolates from CFMPs produced aflatoxins. A. flavus levels associated with CFMPs increased rapidly during the initial part of the 12-month incubation period, whereas the percent aflatoxigenicity continued to increase even after A. flavus density leveled off later. During 12 months incubation, A. flavus DNA amounts recovered from CFMPs increased in soils with all levels of indigenous A. flavus, with the largest increases (119.1%) occurring in soil containing the lowest indigenous A. flavus. These results suggest that burying compostable film in soil, or application of compost containing CFMPs, may reduce soil quality and increase risk of adverse impacts from elevated aflatoxigenic A. flavus populations in soil.

Effects of Purple Seed Stain on Seed Quality and Composition in Soybean.

Purple seed stain disease, caused by (Cercospora kukuchii), is a major concern in soybean (Glycine max (L.)) in Mississippi, USA, due to its effects on seed quality, reducing soybean seed grade and potential market price at elevators. Therefore, investigating the effects of purple seed stain (PSS) on seed quality (germination and vigor) and seed composition (nutrition) is critical. The objective of this study was to investigate the effects of PSS on seed harvest index, seed germination, seed vigor, and seed composition components (protein, oil, fatty acids, and sugars). A field experiment was initiated in 2019 in Stoneville, MS, at the Delta Research and Extension Center (DREC) on a Commerce silt loam soil (fine-silty, mixed, superactive, nonacid, thermic Fluventic Epiaquepts). Soybean variety Credenz 4748 LL was used. The results showed that infected (symptomatic) seed had a 5.5% greater Seed Index (based on 100 seed weight) when compared to non-infected (non-symptomatic, as control) seed. Non-infected seed had greater percent germination and seedling vigor when compared to infected seed. Germination was 30.9% greater and vigor was 58.3% greater in non-infected seed. Also, the results showed that infected seed with PSS had higher protein content and some amino acids. No changes in total oil and fatty acids. Sucrose and stachyose were lower in infected seed than in non-infected seed. The research showed that PSS impacted seed health and seed quality (germination and vigor) and seed composition (protein, sugars, and some amino acids). Purple stained seed should be avoided when planting and should be managed properly as low germination is a potential risk. Planting population should be adjusted accordingly due to lack of germination and vigor if PSS is present. This research help growers for purple seed management, and scientists to further understand the potential negative impact on seed quality and nutrition. Further research is needed before conclusive recommendations are made.