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Seed dormancy is an important breeding trait for the development of certain types of peanut cultivars. Peanut cultivars with seed dormancy can inhibit preharvest sprouting in which the sprouting may increase susceptibility to preharvest aflatoxin contamination. The recombinant inbred line (RIL) mapping population derived from a cross of Tifrunner, a dormant Runner type, and GT-C20, a non-dormant Spanish type, were planted in the field for 2 years, and the freshly harvested seeds were used for seed dormancy tests at 7, 14, 21, and 28 days during germination. There were three RILs from 2-year tests with no dormancy (T48, T83, T160) and two lines with strong dormancy (T11, T163). This RIL population was genotyped using peanut SNP array ‘Axiom_Arachis’ 58 K, and two major seed dormancy QTLs were anchored on chromosome A04 and A05 with 43.16% and 51.61% of the phenotype variation explained (PVE), respectively. The QTL mapped on chromosome A05 had been anchored on a physical map interval of 98 kb (157.538–157.636 Mb) from which a possible candidate gene (Arahy.KB746A, ethylene-responsive transcription factor) was identified. Reference to the peanut physical map and flanking sequences, DNA markers can be developed for these two QTLs and used in marker-assisted breeding selection for seed dormancy in peanut.

Seeds kept in long-term storage are essential for maintaining genetic resources of crops and other plant materials in seed banks and national germplasm systems. But seeds undergo chemical changes over time as part of the ageing process that result in reduced germination rates and seedling normalcy. For example, oilseed crops such as peanuts are particularly vulnerable to oxidation and rancidification due to their high oil content. To test the effect of storage time on seed oil in peanuts, we grew different accessions and harvested fresh seeds to compare the oil composition of new seeds with seeds aged in storage for varying lengths of time. Out of the nine fatty acids detected and measured by gas chromatography, five including oleic, gadoleic, behenic, lignoceric and cerotic acids differed significantly between new and old seeds. Additionally, old seeds accumulated up to four oxidation products together averaging about 1% of the total oil composition. The concentration of these oxidation products was positively correlated with the age of the seeds, increasing linearly up to more than 6% of the total in the oldest seeds. The presence and concentration of oxidation products measured using simple chromatography techniques can be used as an initial indication of quality and viability in older seed inventories stored in germplasm repositories.

This research aimed to compare the effects of monosodium glutamate (MSG) and its alternatives on sensory characteristics of chicken soup. High-performance liquid chromatography analysis was carried out to quantify umami substances in potential MSG alternatives. Two mushroom extracts (CE and MC), one tomato extract (TC), and one yeast extract (YE) powders were selected due to their high equivalent umami concentration (EUC). These extracts together with MSG were then applied individually at four different levels (CE, MC, TC, MSG: 0.05%, 0.1%, 0.2%, 0.4%; YE: 0.0125%, 0.025%, 0.05%, 0.1%) in chicken soup in order to compare their impact on major sensory attributes using the degree of difference from control (DODC) test. Our results showed that all four extracts at all the usage levels exhibited an enhancement effect on the overall flavor, meaty flavor, saltiness, and umami taste. The extent of enhancement depended on the type of the alternative and its usage level. Higher levels of MSG alternatives (except YE) suppressed the chicken flavor. YE had similar enhancement effects as MSG on umami and salty tastes already at lower usage levels. At the lowest concentration, TC showed a stronger enhancement effect than MSG, but its effect on most attributes decreased as the usage dose increased. Compared to CE, the other mushroom extract MC resembled MSG at most levels. Overall, the closest synergistic effect in chicken soup was noted with 0.1% MSG, 0.1% MC, and 0.025% YE. PRACTICAL APPLICATION: This study compared the enhancement effects of MSG and selected alternatives in chicken soup. Results will help food manufacturers who would like to replace MSG with natural umami substances in soup products to enhance flavor and reduce sodium chloride.

High oleate is an important seed quality trait frequently incorporated in peanut varieties. Crop wild relatives (CWR) are potentially useful genetic resources for cultivar improvement through genetic introgression; but for wild peanut species, many chemical or nutritional traits are not well characterized. A mutant from Arachis veigae S. H. Santana & Valls (2n = 2x = 20), with increased oleic and very long chain (C ≥ 22) fatty acid content was identified from screening 209 accessions of 45 species using gas chromatography (GC). The A. veigae (formerly A. sylvestris) accession, VVeSv 8373 (PI 688970) contained 55.5% oleic acid in seeds, significantly higher than the average (18.3%) of other accessions within the same species and also significantly higher than the average (37.0%) of all wild peanut accessions evaluated. A C37T substitution was identified by sequencing the coding region of FAD2H, resulting in the nonsense mutation of Q13* (a premature stop codon). This functional mutation may significantly reduce the fatty acid desaturase (FAD) activity and result in the enhanced oleate level. Arachis veigae also contained a high percentage of very long-chain (C ≥ 22) fatty acids, and their variation identified in this study is also discussed and compared with other species. The mutant with such an altered fatty acid composition may be useful for potentially improving seed or food nutrition quality.

Sesame (Sesamum indicum L.) is an important oil seed with edible and potentially nutritional and medical uses in most countries and may show variability for bioactive concentrations. The objective of this study was to evaluate seed production weights, numbers, oil, protein, lignan, tocopherol, and fatty acid concentrations in seeds from 8 randomly diverse sesame genotypes with various seed coat colors over two years. Oil analysis were conducted using NMR (nuclear magnetic resonance) on a Bruker mq-one minispec. Protein was measured by combustion on an Elementar Rapid N Exceed nitrogen analyzer. Lignan and tocopherol compounds were prepared and analyzed by HPLC (high performance liquid chromatography) on an Agilent 1100. Fatty acids were separated by gas chromatography on an Agilent 7890A with a 15 m DB23 analytical column and FID (flame ionization detector). The bioactives and 1000 seed weights were significantly influenced by genotype, except for heptadecenoic acid (17:1), while total seed weight, total seed numbers, sesamolin, γ-tocopherol, and oleic acid (18:1) were influenced by year. Oil, protein, δ-tocopherol, and margaric acid (17:0) showed a year x genotype interaction. Significant 1000 seed weights ranged from 1.8 to 3.3 g while oil and protein concentrations significantly ranged from 29.43–54.69% and 13.92–21.76%, respectively. Sesamin and sesamolin ranged significantly from 0.55 to 8.98 mg/g and tocopherols ranged from 0 to 239.58 μg/g. The major unsaturated fatty acids, oleic (18:1) and linoleic (18:2) acids significantly ranged from 26.60 to 54.85 % while the minor unsaturated fatty acids ranged from 0.13 to 0.89 %. The saturated fatty acids significantly ranged from 0 to 10.58 %. Several correlations were observed among the bioactives. The 8 sesame genotypes can be used in breeding programs to develop new cultivars with enhanced bioactives.

Protein percentage and mineral concentrations are important parameters for determining the seed nutrition quality. Although the U.S. peanut mini-core collection is the important genetic resources for peanut breeding programs, the variability in protein percentage and mineral concentrations for this mini-core has not been well evaluated. The lack of information may hinder its optimum utilization. The seeds from this mini-core were collected from two field seasons. Their protein percentage and mineral concentrations of 95 accessions were determined by nitrogen analysis and inductively coupled plasma – optical emission spectrometry, respectively. Significant variability in the seed protein percentage among accessions was revealed, ranging from 20.6 to 30.4%, with an average of 26.2%. Significantly higher variability in plant micronutrient mineral concentrations (more than two-fold for B, Cu, Fe, Mn, Mo, Na, Ni, and Zn) than in macronutrient mineral concentrations (less than two-fold for K, Mg, P, and S) was also identified among accessions. Calcium however was an exception, demonstrating 3.7-fold variability among the accessions evaluated. Three accessions (PI 497517, PI 493547, and PI 429429) were identified as lines containing high seed levels of both Fe and Zn. Correlation coefficients were also determined among 28 investigated seed chemical composition traits, using data from a previous study with the same samples. Protein percentage was significantly negatively correlated with seed weight, oil, and oleate percentage. Several mineral elements (Fe, Mg, Mn, and Zn) were also significantly negatively correlated with oleate percentage. The results from this study will be useful for peanut nutrition breeding and food product development.

Bamboo shoots and leaves are valuable food sources for both humans and livestock. The USDA-ARS NPGS (National Plant Germplasm System) collections hold 93 bamboo species in 20 genera. Total leaf protein, amino acid composition and elemental content for these important genetic resources had never been quantified. Lack of nutrition information hinders germplasm utilization. The above-mentioned nutritional traits were evaluated from these 93 species in this study. Leaf protein content among bamboo species ranged from 8.12 to 16.33% with an average of 12.84%. This average was higher than 9.0% observed for switchgrass leaves, but considerably lower than 32.48% in cassava leaves. For 18 quantified amino acids, there was more than a twofold variation among the samples evaluated. For 12 quantified mineral elements, there was significant variability from the low end (4.2-fold, 2.27–9.52 mg/g calcium; 4.4-fold, 56.17–246.43 µg/g sodium) to the high end (61.5-fold, 17.67–1087.0 µg/g manganese; 40.8-fold, 42.0–1713.5 µg/g aluminium). Due to their variability in leaf nutritive value, bamboo species should be carefully chosen when they are used as a feedstock. The results from this study will be useful for the bamboo industry, producers and consumers.

The level of oleic acid in peanut seed is one of the most important factors in determining seed quality and is controlled by two pairs of homeologous genes (FAD2A and FAD2B). The genotypes of eight F8 breeding lines were determined as AABB, aaBB, AAbb, and aabb by real-time polymerase chain reaction and sequencing. Fresh seeds were collected from five seed developmental stages and, after drying, were used for chemical analysis. Our results showed that (1) as seeds developed, seed weight, oil content, and oleic acid level significantly increased, whereas four other fatty acid levels decreased, but protein content and another four fatty acid levels did not significantly change, (2) FAD2A/FAD2B significantly affected fatty acid profiles but not oil and protein contents, and (3) the data were consistent across 2 years. The variability of seed quality traits revealed here will be useful for peanut breeders, farmers, processers, and consumers.

In order to produce clean energy from renewable lignocellulosic biomass, the feedstock must be pretreated by means of one or combined cost-competitive methods to make the entire process economically feasible. Fungal cultivation may be one promising pretreatment approach, for which the effectiveness varies with different fungal strains in regard to biomass loss, sugar yield, enzyme loading, and co-product yield. Wild-type fungus might have a great potential in pretreating feedstock for both lowered enzyme loading and beneficial co-product enzyme production. In this study, 25 diverse fungal strains were screened for pretreatment of switchgrass biomass with regard to co-production of beneficial enzymes and the subsequent saccharification process, by examining switchgrass biomass loss, effectiveness of enzymatic hydrolysis, and ligninolytic activity. The most promising fungus was identified as an inedible mushroom, Agaricus molybdites (H4) with the highest saccharification efficiency and ligninolytic enzyme production. Additionally, eight accessory enzymes, e.g. pectinase, esterase, xylanase, β-glucosidase, chitinase, lipase, α-amylase, and laccase, were found to assist cellulase in enhancing saccharification of H4 pretreated switchgrass to varying degrees. Our experimental results suggest that pretreatment of switchgrass with an appropriate fungus, followed by exposure to cellulase and synergistic accessory enzymes can be an effective strategy for maximizing the process of saccharification.

Bamboo shoots and leaves are nutritious, providing food for human and animal consumption. However their nutrient value depends on a number of factors including the bamboo species (e.g. taxon), harvesting season and growing location. Leaf crude protein content, amino acid composition and mineral element concentration were quantified from leaf samples collected from 222 accessions representing two bamboo types (temperate/tropical), two growing seasons (dry/wet) and three locations (PGRCU-Byron, GA; TARSMayaguez, PR; and Govardhan Gardens-Mayaguez, PR). Significant variability in leaf nutrient value was identified among accessions, types, growing locations and harvesting seasons. On average, bamboo leaf tissue contained 12.92% protein with relatively high percentages of leucine (Leu, 8.97%) and proline (Pro, 7.98%) and low percentages of tryptophan (Trp, 1.69%) and histidine (His, 2.01%). Bamboo leaves also contained relatively high concentrations of the macro-mineral elements potassium (K, 12.17mg/g) and calcium (Ca, 5.37mg/g), high concentrations of the micro-mineral elements manganese (Mn, 388.76 μg/g) and iron (Fe, 123.19 μg/g), and low concentrations of boron (B, 7.8 μg/g) and zinc (Zn, 28.56 μg/g). PI 647932 and TARS 182857 contained the highest and lowest protein content (21.69% and 5.78%), respectively. Temperate bamboos contained a significantly higher percentage of protein (13.02%) than tropical bamboos (12.71%). Leaf samples harvested from the dry season contained a significantly higher percentage of protein (13.12%) than leaf samples harvested from the wet season (12.70%). The leaf samples harvested from Govardhan Garden location contained a higher percentage of protein (13.40%) than from Byron (12.65%) and TARS (12.89%) locations. The leaf samples harvested from Govardhan Garden contained a significantly higher iron concentration (151.22 μg/g) than from the other two locations (118.19 μg/g, 111.52 μg/g), whereas the leaf samples collected from Byron contained a significantly higher zinc concentration (36.03 μg/g) than what was observed from the other two locations (27.83 μg/g, 22.11 μg/g). There was no significant difference in iron and zinc concentrations between leaf samples collected from dry or wet seasons. Tropical bamboo leaves contained a higher iron concentration (131.74 μg/g) than temperate bamboo leaves (118.95 μg/g), whereas temperate bamboo leaves contained a significantly higher zinc concentration (29.82 μg/g) than tropical bamboo leaves (26.01 μg/g). The information on the bamboo leaf nutrient value related to bamboo accessions, types, growing location and harvesting season will be very useful for bamboo growers, processors and consumers.

Castor is an important oilseed crop and although its oil is inedible, it has multiple industrial and pharmaceutical applications. The entire US castor germplasm collection was previously screened for oil content and fatty acid composition, but its genetic diversity and population structure has not been determined. Based on the screening results of oil content, fatty acid composition, and country origins, 574 accessions were selected and genotyped with 22 polymorphic EST-SSR markers. The results from cluster analysis, population structure, and principal component analysis were consistent, and partitioned accessions into four subpopulations. Although there were certain levels of admixtures among groups, these clusters and subpopulations aligned with geographic origins. Both divergent and redundant accessions were identified in this study. The US castor germplasm collection encompasses a moderately high level of genetic diversity (pairwise dissimilarity coefficient = 0.53). The results obtained here will be useful for choosing accessions as parents to make crosses in breeding programs and prioritizing accessions for regeneration to improve germplasm management. A subset of 230 accessions was selected and will be planted in the field for establishing a core collection of the US castor germplasm. Further evaluation of the US castor germplasm collection is also discussed.

Sesame germplasm harbors genetic diversity which can be useful for sesame improvement in breeding programs. Seven accessions with different levels of oleic acid were selected from the entire USDA sesame germplasm collection (1232 accessions) and planted for morphological observation and re-examination of fatty acid composition. The coding region of the FAD2 gene for fatty acid desaturase (FAD) in these accessions was also sequenced. Cultivated sesame accessions flowered and matured earlier than the wild species. The cultivated sesame seeds contained a significantly higher percentage of oleic acid (40.4%) than the seeds of the wild species (26.1%). Nucleotide polymorphisms were identified in the FAD2 gene coding region between wild and cultivated species. Some nucleotide polymorphisms led to amino acid changes, one of which was located in the enzyme active site and may contribute to the altered fatty acid composition. Based on the morphology observation, chemical analysis, and sequence analysis, it was determined that two accessions were misnamed and need to be reclassified. The results obtained from this study are useful for sesame improvement in molecular breeding programs.

Teramnus labialis and T. uncinatus are both underutilized legume species. Teramnus labialis is used as food in India while T. uncinatus has potential use in pasture mixes. Photoperiod-sensitive Teramnus accessions were grown in the greenhouse from 2010 to 2011 and evaluated for flavonol content, oil%, and fatty acid compositions. Significant variations for seed numbers produced, flavonol content, oil%, and fatty acid compositions were detected. Seed numbers ranged from 16 to 3,792 in both species. Teramnus accessions produced more quercetin (ranging from 0.615 to 2.228 mg/g) in their seeds than the other flavonols. However kaempferol and isorhamnetin content ranged from 0 to 0.066 and 0 to 0.086 mg/g (dry seed weight basis), respectively among all accessions. Oil% ranged from 2.65 to 5.64% and more oleic, linoleic, and linolenic acids ranging from 6.69 to 25.97, 31.82 to 41.44, and 17.7 to 32.66%, respectively, were produced among all Teramnus accessions. The seeds from all Teramnus accessions also produced the least saturated fatty acid compositions (ranging from 0.08 to 15.36%). Several significant correlations were also detected for these traits among the accessions. Quercetin showed highly significant positive correlations with kaempferol (r = 0.59, p.0001), oil% (r = 0.58, p.0001), and oleic acid (r = 0.31, p.001). Quercetin also showed a significant negative correlation with linoleic acid (r = -0.49, p.0001). These correlations are important because useful breeding procedures could be conducted on improving flavonol, oil%, and fatty acid compositions in Teramnus labialis and T. uncinatus accessions.

A late fall frost may significantly affect sugar crops’ stem sugar composition, yield and juice quality for biofuel and bioproduct manufacture. Research on the effects of late fall frost in sugarcane is well documented, but information is lacking for sweet sorghum. Three and six commercial cultivars of sugarcane and sweet sorghum, respectively, were selected and evaluated for exposure to a late fall frost (-2.8&degC) in Griffin, Georgia, USA. Under the same controlled environmental conditions in a screen house, the late fall frost induced more damage to sugarcane than sweet sorghum stems. The frost caused damage to sugarcane tissue and for juice to exude from stems, whereas similar behavior was not observed for sweet sorghum. In both sugarcane and sweet sorghum, the glucose/fructose ratio was significantly reduced, but this change may not be totally directly related to the frost effect. Overall, these initial results suggest that sweet sorghum may have a better tolerance to fall frost than sugarcane. Two sweet sorghum cultivars, Grassl and M81E, responded well to the late fall frost, and they can possibly be used as feedstocks for biofuel/bioproduct manufacture in areas susceptible to frosts including northern regions of the Southeastern US.

Some Senna species are important medicinal plants used worldwide and may show variation for sennoside concentrations. The USDA, ARS, PGRCU (United States Department of Agriculture, Agricultural Research Service, Plant Genetic Resources Conservation Unit) curates several Senna species including candlebush [S. alata (L.) Roxb.], Alexandrian senna [S. alexandrina Mill.], S. angulata (Vogel) H.S. Irwin & Barneby, S. covesii (A. Gray) H.S. Irwin & Barneby, S. hirsuta var. hirta H.S. Irwin & Barneby, S. hirsuta var. leptocarpa (Benth.) H.S. Irwin & Barneby, S. occidentalis (L.) Link, and S. uniflora (Mill.) H.S. Irwin & Barneby. The natural products including sennoside A and B are the primary laxative ingredients in many medicinal products. However, it is unknown if sennoside A and B are found in many of these Senna species and at what concentrations. The objective of this study was to evaluate sennoside A and B content from leaves of 14 and pods of four accessions including eight Senna species over two years and locations. Sample analysis was performed by HPLC (high performance liquid chromatography) on an Agilent 1100 with an auto-sampler and diode array detector. Significant accession and location x accession effects were observed for sennoside A and B. Mean separations revealed that leaves from S. alata produced significantly more sennoside A (8.55 mg/g) than all other species. However, immature pods from S. alexandrina produced the significantly highest sennoside B (16.19 mg/g) content. While this is a preliminary analysis, it provides evidence for higher levels of sennoside A and B in S. alata and S. alexandrina than in S. angulata, S. covesii, S. hirsuta var. hirta, S. hirsuta var. leptocarpa, S. occidentalis, and S. uniflora. These results show that both S. alata and S. alexandrina produced the highest sennoside concentrations. However, additional studies are required to verify sennoside content in other Senna species and organs including Senna pods.

Several Desmodium species are adapted to the environment of Griffin, Georgia, USA. The determination of flavonoid concentrations, oil content and fatty acid compositions of 25 Desmodium accessions representing five species (D. discolor Vogel, D. incanum (G.Mey.) DC., D. intortum (Mill.) Urb., D. sandwicense E. Mey. and D. tortuosum (Sw.) DC.) would add value to the members of the genus Desmodium for possible use as livestock health supplements. In this study, the seeds of these 25 accessions were evaluated for flavonoid concentrations, oil content and fatty acid compositions using high-performance liquid chromatography, nuclear magnetic resonance and gas chromatography, respectively. Several accessions exhibited significantly greater values for all the traits than the controls. The Desmodium accessions produced significantly greater concentrations of quercetin and kaempferol than the best control accession (D. incanum, PI 477072). However, all the Desmodium accessions produced significantly greater concentrations of isorhamnetin and luteolin than the control accessions. All the Desmodium accessions had greater linoleic (18:2) and behenic (22:0) acid content than a couple of D. incanum control accessions in 2010 and 2011. Significant correlations were observed between several traits. The concentration of quercetin was significantly correlated with that of kaempferol (r2= 0.69***); however, the concentration of quercetin exhibited a significantly negative correlation (r2= − 0.41*) with that of isorhamnetin. Oil content was significantly correlated with palmitic acid (r2= 0.61**), stearic acid (r2= 0.81***), linolenic acid (r2= 0.58**) and lignoceric acid (r2= 0.80***) content. This information will assist breeders and other scientists in developing superior cultivars with optimum levels of flavonoid concentrations, oil content and fatty acid compositions for many of these Desmodium species.

Horse gram [Macrotyloma uniflorum (Lam.) Verdc.] seeds containing high concentrations of fatty acids, flavonols and minerals should provide government, public and private organizations with a nutritious and healthy food for use by malnourished and food deprived people worldwide. Seeds from seven horse gram accessions, geographically adapted to Griffin, GA, USA were analyzed for fatty acid, flavonol, and mineral concentrations using gas chromatography, reverse-phase high performance liquid chromatography, and inductively coupled plasma-optical emission spectroscopy, respectively. Significant year effects occurred for stearic, oleic, linoleic, arachidic, gadoleic, and lignoceric acids. Oleic, linoleic, and linolenic acid ranged from 8.9%–16.8%, 40.3%–45.6%, and 11.6%–14.3%, respectively, as percent of total fatty acids measured (total oil ranged from 2.32% to 2.87%). Seed concentrations of myricetin, quercetin, and kaempferol ranged from 0–36 μg/g DW, 0–27 μg/g DW, and 240–316 μg/g DW, respectively and the only year effect was observed for kaempferol among the horse gram accessions. Year effects were found for Fe, K, Mg, Mn, Ni, and S. Mean concentrations of macrominerals (Ca, K, Mg, P, and S) and microminerals (Cu, Fe, Mn, Ni, and Zn) ranged from 1.3–14 mg/g DW, and 1.0–95.0 μg/g DW, respectively. Several correlations were observed among several fatty acids, flavonols, and minerals. The mono-unsaturated fatty acid, oleic acid correlated significantly with linoleic acid (r = −0.64), arachidic acid (r = −0.61), Ca (r = 0.50) and Zn (r = 0.51, all at P < 0.01). The flavonol, myricetin correlated significantly with quercetin (r = 0.92, P < 0.0001), while quercetin correlated with Ca (r = 0.82, P < 0.0001) and kaempferol correlated with Mg (r = 0.61, P < 0.01). Several mineral correlations were found including Fe with K (r = 0.66) and Mg (r = 0.56, both at P < 0.01). These seven horse gram accessions can be used in breeding programs to facilitate the production of superior cultivars with favorable fatty acid profiles, flavonol content, and mineral compositions.

Sweet sorghum has become an important feedstock for bioethanol production. Total sugar yield and multiple harvests can directly affect ethanol production cost. Little is known about stem traits and multiple harvests that contribute to sugar yield in sweet sorghum. Stem traits were evaluated from 25 sweet and grain sorghum accessions. Stems were harvested twice at the soft-dough stage and the stems were pressed with a hydraulic press. Sugars in the stem juice were quantified by high performance liquid chromatography. Sweet sorghum produced five times more fresh stem weight and dry stem mass (830 gand164 g) than grain sorghum (150 gand27g). Sweet sorghum produced a much higher volume of juice and higher yield of sugars (366 ml and42 g) per stem than grain sorghum (70 ml and4 g). Significant variability in fresh stem weight (72 - 1837 g), juice volume (31 - 753 ml), sugar yield (3 - 81 g), dry stem mass (14 - 383 g), and sugar yield/dry stem mass ratio (0.11 - 0.53) per stem was detected among sweet sorghum accessions. Stem sugar yield was significantly correlated with stem fresh weight and juice volume. Sorghum was harvested twice within one growing season resulting in some sweet sorghum accessions producing double amount of sugars. Sweet sorghum produced three times more dry mass weight (bagasse) than fermentable sugar weight. To reduce feedstock cost, methods have to be developed for efficiently utilizing bagasse. Our results showed high fresh stem weight, high ratio of sugar yield to dry stem mass, and double harvests are prime traits to boost sugar yield. Sweet sorghum may be suitable for multiple harvests in certain regions of theU.S.TheU.S.sweet sorghum collection needs to be screened for acces- sions that can be harvested twice with an extended feedstock-production season and used as a feedstock for sustainable and renewable bioenergy production.

Castor has tremendous potential as a feedstock for biodiesel production. The oil content and fatty acid composition in castor seed are important factors determining the price for production and affecting the key fuel properties of biodiesel. There are 1033 available castor accessions collected or donated from 48 countries worldwide in the USDA germplasm collection. The entire castor collection was screened for oil content and fatty acid composition by nuclear magnetic resonance (NMR) and gas chromatography (GC), respectively. Castor seeds on the average contain 48.2% oil with significant variability ranging from 37.2 to 60.6%. Methyl esters were prepared from castor seed by alkaline transmethylation. GC analysis of methyl esters confirmed that castor oil was composed primarily of eight fatty acids: 1.48% palmitic (C16:0), 1.58% stearic (C18:0), 4.41% oleic (C18:1), 6.42% linoleic (C18:2), 0.68% linolenic (C18:3), 0.45% gadoleic (C20:1), 84.51% ricinoleic (C18:1-1OH), and 0.47% dihydroxystearic (C18:0-2OH) acids. Significant variability in fatty acid composition was detected among castor accessions. Ricinoleic acid (RA) was positively correlated with dihydroxystearic acid (DHSA) but highly negatively correlated with the five other fatty acids except linolenic acid. The results for oil content and fatty acid composition obtained from this study will be useful for end-users to explore castor germplasm for biodiesel production.

Natural genetic variation exists in animals and plants. Mining and utilizing this variation may provide benefits for new breed/cultivar development. From screening over 4000 cultivated peanut germplasm accessions, we identified two natural mutant lines (PI 342664 and PI 342666) with 80 % oleic acid by gas chromatography analysis. It is known that FAD2A and FAD2B are the two major genes involved in the conversion of oleic to linoleic acid in peanuts by fatty acid desaturase. Functional mutations in one or both genes can alter the oleate level. By sequencing the coding region of these two genes, we identified a substitution of G448A in FAD2A and a substitution of C301G in FAD2B for both mutant lines. The substitution in FAD2A is the same as a previously identified one, resulting in a missense amino acid substitution of D150N, but the substitution in FAD2B is a new one, resulting in H101D. The new amino acid substitution on FAD2B is located in the first histidine box (one of the active sites) of the fatty acid desaturase and may significantly decrease its activity. Our mutants did not have flowers on the main stem (subspecies hypogaea), but F435 (a previously identified natural high-oleate mutant) had flowers on the main stem (subspecies fastigiata). Therefore, we identified a class of natural mutants from the subspecies hypogaea and provided new additional genetic resources for breeders to use. Our results also demonstrate a good example of the importance and usefulness for preserving natural genetic diversity and utilizing plant germplasm collections.

Peanut, a high-oil crop with about 50% oil content, is either crushed for oil or used as edible products. Fatty acid composition determines the oil quality which has high relevance to consumer health, flavor, and shelf life of commercial products. In addition to the major fatty acids, oleic acid (C18:1) and linoleic acid (C18:2) accounting for about 80% of peanut oil, the six other fatty acids namely palmitic acid (C16:0), stearic acid (C18:0), arachidic acid (C20:0), gadoleic acid (C20:1), behenic acid (C22:0), and lignoceric acid (C24:0) are accounted for the rest 20%. To determine the genetic basis and to improve further understanding on effect of FAD2 genes on these fatty acids, two recombinant inbred line (RIL) populations namely S-population (high oleic line ‘SunOleic 97R’ × low oleic line ‘NC94022’) and T-population (normal oleic line ‘Tifrunner’ × low oleic line ‘GT-C20’) were developed. Genetic maps with 206 and 378 marker loci for the S- and the T-population, respectively were used for quantitative trait locus (QTL) analysis. As a result, a total of 164 main-effect (M-QTLs) and 27 epistatic (E-QTLs) QTLs associated with the minor fatty acids were identified with 0.16% to 40.56% phenotypic variation explained (PVE). Thirty four major QTLs (>10% of PVE) mapped on five linkage groups and 28 clusters containing more than three QTLs were also identified. These results suggest that the major QTLs with large additive effects would play an important role in controlling composition of these minor fatty acids in addition to the oleic and linoleic acids in peanut oil. The interrelationship among these fatty acids should be considered while breeding for improved peanut genotypes with good oil quality and desired fatty acid composition.

Background Peanut is one of the major source for human consumption worldwide and its seed contain approximately 50% oil. Improvement of oil content and quality traits (high oleic and low linoleic acid) in peanut could be accelerated by exploiting linked markers through molecular breeding. The objective of this study was to identify QTLs associated with oil content, and estimate relative contribution of FAD2 genes (ahFAD2A and ahFAD2B) to oil quality traits in two recombinant inbred line (RIL) populations. Results Improved genetic linkage maps were developed for S-population (SunOleic 97R × NC94022) with 206 (1780.6 cM) and T-population (Tifrunner × GT-C20) with 378 (2487.4 cM) marker loci. A total of 6 and 9 QTLs controlling oil content were identified in the S- and T-population, respectively. The contribution of each QTL towards oil content variation ranged from 3.07 to 10.23% in the S-population and from 3.93 to 14.07% in the T-population. The mapping positions for ahFAD2A (A sub-genome) and ahFAD2B (B sub-genome) genes were assigned on a09 and b09 linkage groups. The ahFAD2B gene (26.54%, 25.59% and 41.02% PVE) had higher phenotypic effect on oleic acid (C18:1), linoleic acid (C18:2), and oleic/linoleic acid ratio (O/L ratio) than ahFAD2A gene (8.08%, 6.86% and 3.78% PVE). The FAD2 genes had no effect on oil content. This study identified a total of 78 main-effect QTLs (M-QTLs) with up to 42.33% phenotypic variation (PVE) and 10 epistatic QTLs (E-QTLs) up to 3.31% PVE for oil content and quality traits. Conclusions A total of 78 main-effect QTLs (M-QTLs) and 10 E-QTLs have been detected for oil content and oil quality traits. One major QTL (more than 10% PVE) was identified in both the populations for oil content with source alleles from NC94022 and GT-C20 parental genotypes. FAD2 genes showed high effect for oleic acid (C18:1), linoleic acid (C18:2), and O/L ratio while no effect on total oil content. The information on phenotypic effect of FAD2 genes for oleic acid, linoleic acid and O/L ratio, and oil content will be applied in breeding selection. Electronic supplementary material The online version of this article (doi:10.1186/s12863-014-0133-4) contains supplementary material, which is available to authorized users.

Peanut seeds contain high amounts of oil and protein as well as some useful bioactive phytochemicals which can contribute to human health. The U.S. peanut mini-core collection is an important genetic resource for improving seed quality and developing new cultivars. Variability of seed chemical composition within the mini-core was evaluated from freshly harvested seeds for two years. Oil, fatty acid composition, and flavonoid/resveratrol content were quantified by NMR, GC, and HPLC, respectively. Significant variability was detected in seed chemical composition among accessions and botanical varieties. Accessions were further genotyped with a functional SNP marker from the FAD2A gene using real-time PCR and classified into three genotypes with significantly different O/L ratios: wild type (G/G with a low O/L ratio1.7), heterozygote (G/A with O/L ratio1.4 but1.7), and mutant (A/A with a high O/L ratio1.7). The results from real-time PCR genotyping and GC fatty acid analysis were consistent. Accessions with high amounts of oil, quercetin, high seed weight, and O/L ratio were identified. The results from this study may be useful not only for peanut breeders, food processors, and product consumers to select suitable accessions or cultivars but also for curators to potentially expand the mini-core collection.

This study investigates fungal pretreatment of switchgrass involving solid state fermentation (SSF) to improve saccharification and simultaneously produce enzymes as co-products. The results revealed that the fungus Pycnoporus sp. SYBC-L3 can significantly degrade lignin and enhance enzymatic hydrolysis efficiency. After a 36-d cultivation period, nearly 30% reduction in lignin content was obtained without significant loss of cellulose and hemicellulose, while a considerable amount of laccase, as high as 6.3 U/g, was produced. After pretreatment, pores on switchgrass surface were observed using scanning electron microscopy (SEM). The enzymatic hydrolysis efficiency for the switchgrass with 36-d pretreatment was about 50% greater than the untreated one. Our results suggest that solid state fungal cultivation may be a good method for switchgrass pretreatment, which can simultaneously achieve high efficiency of enzymatic hydrolysis and production of some useful enzymes for other industrial utilization.

We investigated phylogeographic divergence among populations of Galápagos warbler finches. Their broad distribution, lack of phenotypic differentiation and low levels of genetic divergence make warbler finches an appropriate model to study speciation in allopatry. A positive relationship between genetic and geographical distances is expected for island taxa. Warbler finches actually showed a negative isolation by distance relationship, causing us to reject the hypothesis of distance‐limited dispersal. An alternative hypothesis, that dispersal is limited by habitat similarity, was supported. We found a positive correlation between genetic distances and differences in maximum elevation among islands, which is an indicator of ecological similarity. MtDNA sequence variation revealed monophyletic support for two distinct species. Certhidea olivacea have recently dispersed among larger central islands, while some Certhidea fusca have recently dispersed to small islands at opposite ends of the archipelago. We conclude that females have chosen to breed on islands with habitats similar to their natal environment. Habitat selection is implicated as an important component of speciation of warbler finches, which is the earliest known divergence of the adaptive radiation of Darwin's finches. These results suggest that small populations can harbour cryptic but biologically meaningful variation that may affect longer term evolutionary processes.