Oat Seed Research Articles

Using transcriptome sequencing (RNA-Seq) to screen genes involved in β-glucan biosynthesis and accumulation during oat seed development.

Oat (Avena sativa L.) is an annual grass that has a high nutritional value and therapeutic benefits. β-glucan is one of the most important nutrients in oats. In this study, we investigated two oat varieties with significant differences in β-glucan content (high β-glucan oat varieties BY and low β-glucan content oat variety DY) during different filling stages. We also studied the transcriptome sequencing of seeds at different filling stages. β-glucan accumulation was highest at days 6-16 in the filling stage. Differentially expressed genes (DEGs) were selected from the dataset of transcriptome sequencing. Among them, three metabolic pathways were closely related to the biosynthesis of β-glucan by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, including xyloglucan:xyloglucosyl transferase activity, starch and sucrose metabolism, and photosynthesis. By analyzing the expression patterns of DEGs, we identified one CslF2 gene and 32 transcription factors. Five modules were thought to be positively correlated with β-glucan accumulation by weighted gene co-expression network analysis (WGCNA). Moreover, the expression levels of candidate genes obtained from the transcriptome sequencing were further validated by quantitative real-time PCR (RT-qPCR) analysis. Our study provides a novel way to identify the regulatory mechanism of β-glucan synthesis and accumulation in oat seeds and offers a possible pathway for the genetic engineering of oat breeding for higher-quality seeds.

Cytological structures and physiological and biochemical characteristics of covered oat (Avena sativa L.) and naked oat (Avena nuda L.) seeds during high-temperature artificial aging

BackgroundSeed aging, a natural and inevitable process occurring during storage. Oats, an annual herb belonging to the Gramineae family and pooideae. In addition to being a healthy food, oats serve as ecological pastures, combating soil salinization and desertification. They also play a role in promoting grassland agriculture and supplementing winter livestock feed. However, the high lipid and fat derivatives contents of oat seeds make them susceptible to deterioration, as fat derivatives are prone to rancidity, affecting oat seed production, storage, development, and germplasm resource utilization. Comparative studies on the effects of aging on physiology and cytological structure in covered and naked oat seeds are limited. Thus, our study aimed to determine the mechanism underlying seed deterioration in artificially aged ‘LongYan No. 3’ (A. sativa) and ‘BaiYan No. 2’ (A. nuda) seeds, providing a basis for the physiological evaluation of oat seed aging and serving as a reference for scientifically safe storage and efficient utilization of oats.ResultsIn both oat varieties, superoxide dismutase and catalase activities in seeds showed increasing and decreasing trends, respectively. Variance analysis revealed significant differences and interaction in all measured indicators of oat seeds between the two varieties at different aging times. ‘LongYan No. 3’ seeds, aged for 24–96 h, exhibited a germination rate of < 30%, Conductivity, malondialdehyde, soluble sugar, and soluble protein levels increased more significantly than the ‘BaiYan No. 2’. With prolonged aging leading to cell membrane degradation, reactive oxygen species accumulation, disrupted antioxidant enzyme system, evident embryo cell swelling, and disordered cell arrangement, blocking the nutrient supply route. Simultaneously, severely concentrated chromatin in the nucleus, damaged mitochondrial structure, and impaired energy metabolism were noted, resulting in the loss of ‘LongYan No. 3’ seed vitality and value. Conversely, ‘BaiYan No. 2’ seeds showed a germination rate of 73.33% after 96 h of aging, consistently higher antioxidant enzyme activity during aging, normal embryonic cell shape, and existence of the endoplasmic reticulum.ConclusionsROS accumulation and antioxidant enzyme system damage in aged oat seeds, nuclear chromatin condensation, mitochondrial structure damage, nucleic acid metabolism and respiration weakened, oat seed vigor decreased. ‘LongYan No. 3’ seeds were more severely damaged under artificial aging than ‘BaiYan No. 2’ seeds, highlighting their heightened susceptibility to aging effects.

Wild Oat ( Avena fatua ): Crop Mimicry and Herbicide Resistance

Abstract Wild oat ( Avena fatua ) is a weed species that through crop mimicry survive in conventional managed farmlands, particularly in cereal crops such as wheat and barley. Adaptation of wild oat likely dates back around 9000 years when domestication of cereal species began in the Fertile Crescent and around the Mediterranean Sea. So far, wild oat has been described as a troublesome weed in 44 countries across temperate parts of the world. Wild oat reduces crop yields due to its competition for nutrients, water and light. Variable seed dormancy results in early maturing plants that add to the soil’s seed bank, and later maturing plants that contaminate the harvested grain. Since wild oat seeds resembles cereal grain, they are difficult to remove by mechanical seed cleaning. Seed lots contaminated with wild oat seeds are downgraded since it reduces the suitability as food and feed. Contaminated seedlots used for planting is a source of long distance spread of the weed. Herbicide application is an important part of wild oat control in areas with intensive wheat and barley production. Herbicide labels typically recommend the optimal size of wild oat seedlings and crop plants for best control. However, timing of an application can be difficult when wild oat plants are at different growth stages. The majority of herbicides are grouped according to the mode-of-action in cells of weed plants either inhibiting specific enzymes or entire metabolic pathways. Repeated use of herbicides with the same mode-of-action creates a selection pressure that can result in development of wild oat populations resistant to these herbicides. There is a direct relationship between the number of wild oat plants treated with herbicides and the risk of selecting for resistant plants. Thus, best management practices (BMP) aim to reduce the number of wild oat seed in the field, and include rotating between herbicides with different mode-of-action, and following recommendations on herbicide labels regarding plant growth stages and dosage. Cultural practices include rotating crop species and optimizing crop health, planting of weed-free seed, and cleaning of machinery between fields. Wild oat’s adaptations for crop mimicry and herbicide resistance make it problematic to manage but incorporating BMPs into an integrated approach can help. Information © His Majesty the King in Right of Canada, as represented by the Minister of Agriculture and Agri-Food Canada.

Environmental conditions predetermine quality, germination, and innate antioxidants pool in sea oat (Uniola paniculata L.) seeds

Secondary metabolites such as antioxidants are critical components that protect seeds from stress damage during seed development, desiccation, and ex-situ storage. Antioxidants are essential determinants of seed quality, longevity, and persistence. Understanding the environmental factors that regulate the accumulation, content, and function of antioxidant pools in sea oat seeds is critical for gene banking and understanding the environmental impacts on seed quality. Germination, viability, and Trolox Equivalent Antioxidant Capacity (TEAC) were analyzed on seeds from 18 sea oat populations from the US Atlantic and Gulf of Mexico coasts. We first assessed baseline TEAC, followed by TEAC performed on imbibed seeds for 36 h at 35/25°C during the day and night, respectively. Then, we analyzed the relationship of the antioxidant pools from these 18 sea oat populations to sampling site environmental classifications. Higher baseline antioxidants were common in regions with extreme environmental conditions corresponding to sea oat populations growing at latitudinal extremes characterized by warmer and colder temperatures. Baseline antioxidants did not correlate with prevailing seed germination. However, higher concentrations of antioxidants following imbibition were associated with poor seed germination in warmer conditions. Our results indicate that climatic conditions and environmental components associated with temperatures and precipitation may largely influence the innate pool of antioxidants in sea oat seeds. Also, a high amount of antioxidants following sea oat seed imbibition suggest seed damage or poor viability influenced by environmental stress conditions during seed development.

Physiological and Biochemical Mechanisms of Exogenous Melatonin Regulation of Saline–Alkali Tolerance in Oats

Saline–alkali stress is one of the major factors limiting oat seed germination. The regulatory role of melatonin (MT) as a naturally occurring active substance is well known, but the mechanism of MT-mediated intrinsic physiological regulation of oat seed germination under saline–alkali stress is unclear. Therefore, this study investigated (1) the variability of different MT seed soaking concentrations and times on the germination of oat seeds under saline–alkali stress, and (2) the possible physiological regulatory mechanisms of MT on the germination of oat seeds under saline–alkali stress. The results showed that seed vigor was significantly reduced under saline–alkali stress, and seed germination of oats was significantly inhibited; different concentrations of MT seed soaking treatments improved the germination rate, germination potential, germination index, vigor index, root length, germ length, fresh weight, and dry weight; and, overall, treatment improved seed germination and exhibited the phenomenon of “low promotion and high inhibition”. The 100 μmol·L−1 MT seed soaking treatment effectively enhanced the activities of seed antioxidant enzymes (SOD, POD, CAT, and APX) and nonenzymatic antioxidants (GSH and AsA), affected the AsA-GSH cycle, and effectively increased the contents of osmoregulatory substances (proline, protein, and soluble sugar) by reducing levels of H2O2, OH−, and MDA, thus enhancing the tolerance of oats to saline–alkali and promoting seed germination. In conclusion, MT has a positive effect on the saline–alkali tolerance of oat seeds.

Application of the IR spectrometry method in the screening study of various oat species

BACKGROUND: The infrared reflection spectroscopy application method for rapid assessment of biochemical parameters in various types of oats is shown. On the basis of the biochemical data obtained in the laboratory of VIR, calibration models of protein, oil and starch content were constructed.&#x0D; AIM: The aim of the study is to develop an express method of near-infrared spectroscopy (NIRS) spectroscopy to determine the main biochemical parameters in oat seeds and to build calibration models for the MATRIX-I IR analyser to quantify the mass fraction of protein, oil and starch in oat seeds based on data obtained by traditional methods.&#x0D; MATERIALS AND METHODS: Biochemical quality indicators (protein, oil, starch) were studied on seeds of filmy oats (Avena sativa L.) grown in 20152016 in the North-Western Region of the Russian Federation. Calibration models for the determination of protein, oil and starch in oat seeds (98 samples, harvest 20142015) were developed for the MATRIX-I IR analyzer by Bruker Optics (Germany). Values obtained by traditional chemical methods of analysis were used to construct calibration models. Oat seed oil was determined by the Soxlet method, protein by the Kjeldahl method, starch by the Evers polarimetric method. All indicators were recalculated for dry weight.&#x0D; RESULTS AND CONCLUSION: The reliability of the developed models was checked by the results of protein, oil and starch determination in the seeds of the test batch according to the indicator of the calibration correctness. The data obtained using the calibration curve on the MATRIX-I device had no significant differences with the results of chemical studies. Therefore, calibration can be used for screening analysis for protein, oil and starch content in oat samples. This method allows you to save valuable material, increase labour productivity due to the speed of obtaining data, does not require reagents and is safe.

Mechanical scarification technique breaks seed coat-mediated dormancy in wild oat (Avena fatua)

AbstractWild oat is a herbicide resistance-prone global weed species that causes significant economic losses in dryland and horticultural agriculture. As a result, there has been a significant research effort to control this species. A major impediment to this research is the seed coat-mediated dormancy of wild oat, which requires a labor-intensive incision or puncturing of the seed coat to initiate seed germination. This study defines the most efficient settings of a mechanical thresher to overcome wild oat seed dormancy and then validates these settings using multiple populations collected from the Western Australian grain belt. We also compare the effects of rapid mechanical scarification and known germination stimulus tactics such as scarification with sulfuric acid (H2SO4), partial endosperm removal, sandpaper scarification of the seed coat, and immersion in sodium nitroprusside (NO donor SNP) solution on wild oat seedling growth rate. Threshing treatment of 1,500 rpm for 5 s provides equivalent germination compared with manually puncturing individual wild oat seeds, with no difference in seedling relative growth rate. The mechanical scarification of seeds using the thresher resulted in greater germination (66%) than H2SO4 scarification (0%), partial endosperm removal (10%), sandpaper seed coat scarification (25%), and exposure to NO donor SNP (34%). This study demonstrates that the physical dormancy of wild oat can be rapidly overcome using a commercially available mechanical thresher.

Making of Low Calorie Functional Yoghurt Drink Enriched with Oat Seed and Stevia Leaves Powders (as Sweeteners)

Functional yoghurt drinks ( Y.D ) were prepared as follows : treatment A ( Y.D. + 3% oat + 6% sucrose ) , treatment B ( Y.D. + 3% oat +0.25 % stevia ) , treatment C ( Y.D. + 6% sucrose , control ) .All drinks were stored at 5 ± 1 °C for 15 days and analyzed for chemical , microbiological , rheological , and sensory properties . Total energy , total solids ( T.S ) , fat , total protein , carbohydrate and ash contents were found highest in treatment A , during storage period .Treatment A recorded the highest values of viscosity and the lowest rate of whey separation . Total dietary fibers was found higher in fresh treatment B . Seven essential amino acids ( EAA) and ten Non-essential amino acids ( NEAA ) were detected in all fresh Y.D samples . Valine amino acid was the predominant amino acid in EAA and Glutamic acid was the corresponding one in NEAA. Sulfur amino acids ( Methionine & cysteine ) were also detected in all treatments. The ratio between EAA : NEAA was found highest in Y.D A , followed by B and C , in order . Counts of lactic acid bacteria in yoghurt drinks fortified with oat were found the highest . Yeasts & Molds were appeared in low counts in all treatments at the day 15 of storage . Therefore , low calorie functional Y.D. sweetened with stevia and fortified with oat powder may be produced successfully

Calibration and Experimental Validation of Contact Parameters for Oat Seeds for Discrete Element Method Simulations

Highlights The static friction coefficient and rolling friction coefficient of oat seeds were calibrated by the discrete element method. Two representative oat varieties were selected. The hollow cylinder method and sidewall collapse method were used together to reduce the test error. Abstract . Hulless and shelled oat are two types of oat with major differences in physical appearance. To study the contact parameters between the two different oat seed types, these parameters were delineated with the discrete element method and graphic image processing technology. Using plexiglass as the contact material, the experiments used two different angle of repose measurement methods—hollow cylinder and collapse sidewall devices, to perform bench and simulation experiments on the two different oats. Under different measurement methods, bench experiments measured the angles of repose of the two oat seed types at 33.19°, 33.82° and 22.45°, 23.57°; the static friction coefficient and rolling friction coefficient were the experimental factors, and the angle of repose was the experimental indicator in the simulation. The steepest climbing experiment determined the optimal range of the experimental factor, and the regression equation between the static friction coefficient, rolling friction coefficient and angle of repose was established by a quadratic orthogonal rotation combination experiment. Finally, the angles of repose measured by the bench experiment with the two different measurement methods were treated as target values, the coefficient of static friction and the coefficient of rolling friction were solved; the coefficient of static friction between hulless oats was 0.36, and the coefficient of rolling friction between hulless oats was 0.052; the coefficient of static friction between shelled oats was 0.24, and the coefficient of rolling friction between shelled oats was 0.036. The obtained contact parameters between seeds were input into EDEM, the simulation and bench experiment results were verified. The difference between the simulation results and the actual values was within 3%. The angle of repose of oats after calibration was close to the actual situation, and the calibration results had high reliability and provided a referencefor the measurement of contact parameters between other agricultural crop seeds. Keywords: Calibration, Contact parameters, Discrete element method, Oat.

Mass spectrometric characterisation of avenanthramides and enhancing their production by germination of oat (Avena sativa).

Avenanthramides are amides, with a phenylalkenoic acid (PA) and an anthranilic acid (AA) subunit, which are secondary metabolites of oat. Oat seeds were germinated, extracted, and the avenanthramides analysed by a combination of UHPLC with ion trap and high resolution ESI-MS. Typical fragmentation pathways with corresponding diagnostic fragments belonging to the PA and AA subunits were identified and summarised in a decision guideline. Based on these findings 28 unique avenanthramides were annotated in the oat seed(ling) extracts, including the new avenanthramide 6f (with a 4/5-methoxy AA subunit). Avenanthramide content increased by 25 times from seed to seedling. Avenanthramides 2p, 2c, and 2f, which are commonly described as the major avenanthramides, represented less than 20% of the total content in the seedlings. Future quantitative analyses should, therefore, include a wider range of avenanthramides to avoid underestimation of the total avenanthramide content.

Effects of GA3 and ABA on the Germination of Dormant Oat Seeds

Abstract Oat seed with dormancy characteristics, which can germinate after one season or one year, are used to build and maintain vegetation to protect soils from been damaged by desertification in Northern China. The aim of this study was to estimate the effects of endogenous and exogenous GA3 and ABA on oat seed (var. Baiyan 7) germination. The results showed that seeds without peel hull had lower endogenous ABA content and the ratio of ABA/GA3 than seeds with peel hull. The best GA3 treatment duration for milky ripe, wax ripe, full ripe seeds were 60 min or 120 min, 60 min and 30 min, respectively. Seed germination rate, germination potential and germination index increased before they declined with the increasing of GA3 concentrations. The best GA3 concentration treatment was 100 mg/l, while the turning point was 200 mg/l. The dormancy rate of low temperature storage seeds were higher than those of room temperature storage seeds at each storage time, and both decreased with the increase of the storage time. For the seeds which were new or stored for 1-2 months, the germination rates were enhanced significantly by exogenous GA3. For the seeds that had been stored for over three months, GA3 treatment had no effect on germination rate. Germination rate decreased with the increase of ABA concentrations. The most inhibitive effect, which leaded to a seed germination reduction by 37.7% and 4.0%, appeared, when the concentration of ABA was 500 mg/L and 1000 mg/l, respectively. GA3 could abate the effect which ABA inhibited seed germination.

Influence of tillage, vertical seed distribution, and pyroxasulfone application timing and rate on control of wild oat (Avena fatua L.)

Tillage and new herbicide options may be necessary for the control of herbicide-resistant wild oat. The efficacy of soil-applied herbicides such as pyroxasulfone can be influenced by edaphic factors and weed seed recruitment depth, which varies with tillage system. We investigated the effect of tillage and pyroxasulfone rate when applied in the fall and spring on wild oat biomass at three locations in Alberta in 2014–2015. The vertical position of wild oat seeds, with and without tillage, was examined at each site. Wild oat biomass was greater in untilled plots compared with plots with fall tillage at all locations. In two out of three locations, pyroxasulfone efficacy was superior when applied in the fall compared with spring, possibly influenced by low spring rainfall. A single tillage pass at the Edmonton and Kinsella locations did not affect wild oat seed distribution, but there was an increase in seeds present in the surface layer in the untilled treatment at Lacombe. Tillage, used in combination with soil-applied herbicides, may be an option to achieve acceptable control of herbicide-resistant wild oat.

2-DE Separation and Identification of Oat (Avena sativa L.) Proteins and Their Prolamin Fractions.

At present two-dimensional polyacrylamide gel electrophoresis (2-DE) is the most widely used proteomic tool, which enables simultaneous separation of even thousands of proteins with a high degree of resolution. The quality of 2-DE separation depends on the type of biological material used as a protein source. The presence of interfering compounds (e.g., phenols, as it is the fact in plant material including oat seeds) impedes 2-DE run. With the use of this technique it is possible to analyze the complex protein mixtures, characteristic protein fractions, as well as individual proteins.The purpose of this chapter is to describe the 2-DE technique (the separate stages of the first and the second dimension) for determining the oat protein composition (oat seed proteome), separation and preliminary identification of oat prolamin fractions. Electrophoretically separated proteins are identified on the basis of pI markers (identifying the location of both ends of an IPG strip) and on 2D SDS-PAGE standards. The gel images of oat proteins are analyzed with the help of ImageMaster 2D Platinum 6.0 program (Amersham Bioscience, part of GE Healthcare, Uppsala, Sweden). It allows finding unique spot identifiers for the occurrence of oat prolamin fractions in oat total proteins. The characteristic spots of similar shape and intensity (anchoring spots) and characteristic groups of spots can be searched for the purpose of identification.

Mitochondrial structural and antioxidant system responses to aging in oat (Avena sativa L.) seeds with different moisture contents

We observed the relationship between lifespan and mitochondria, including antioxidant systems, ultrastructure, and the hydrogen peroxide and malondialdehyde contents in 4 h imbibed oat (Avena sativa L.) seeds that were aged with different moisture contents (4%, 10% and 16%) for 0 (the control), 8, 16, 24, 32 and 40 d at 45 °C. The results showed that the decline in the oat seed vigor and in the integrity of the mitochondrial ultrastructure occurred during the aging process, and that these changes were enhanced by higher moisture contents. Mitochondrial antioxidants in imbibed oat seeds aged with a 4% moisture content were maintained at higher levels than imbibed oat seeds aged with a 10% and 16% moisture content. These results indicated that the levels of mitochondrial antioxidants and malondialdehyde after imbibition were related to the integrity of the mitochondrial membrane in aged oat seeds. The scavenging role of mitochondrial superoxide dismutase was inhibited in imbibed oat seeds aged at the early stage. Monodehydroascorbate reductase and dehydroascorbate reductase played more important roles than glutathione reductase in ascorbate regeneration in aged oat seeds during imbibition.

Relationships between ultrastructure of embryo cells and biochemical variations during ageing of oat (Avena sativa L.) seeds with different moisture content

This experiment was designed to determine the relationship between the ultrastructure of the embryo cells and the changes in antioxidant enzymatic activities and lipid peroxidation in oat (Avena sativa L.) seeds with different moisture contents (4, 10 and 16 %) that were aged for 0, 8, 16, 24, 32 and 40 days in 45 °C. The results showed that the declining in the germination percentage and integrity of cell ultrastructure in oat aged seeds were presented during the aged process, and these changes would be enhanced by the higher moisture content. There were consequent changes for biochemical reactions and lipid peroxidation exhibited. For oat seeds with 4 and 10 % moisture content, SOD and CAT were much more sensitive than APX at the early stages of imbibition after mild ageing, the activities of SOD, CAT, APX and MDHAR at 4 h of imbibition decreased significantly (P < 0.05) after being aged from 32 to 40 days. On the contrary, MDA and H2O2 contents both did not increase further. Upon imbibition the activities of DHAR and GR increased after mild ageing, declined after further ageing and maintained a stable level after ageing from 24 to 40 days at those moisture levels. Both activities were higher after ageing at 4 % moisture content than at 10 %. The decline in integrity of ultrastructural cells was related with accumulation of H2O2 during seed ageing, and favoured by the decrease of SOD, CAT, APX and MDHAR activities after imbibition. The activities of antioxidant enzymes and contents of MDA and H2O2 in oat seeds with 16 % moisture content all gradually decreased after ageing from 8 to 40 days, also the ultrastructure of embryo cells was severely damaged. Its ultrastructure was destroyed much more quickly in the seeds with higher moisture content. The level of moisture content could accelerate the seed deterioration, and mitochondrial damages were probably the main reason for oat seed ageing. However, the activities of antioxidant enzymes were the key factor to repair the damage from lipid peroxidation and to maintain the integrity of cell ultrastructure for oat aged seeds during imbibition.

Antioxidant response and related gene expression in aged oat seed.

To evaluate deterioration of oat seeds during storage, we analyzed oxygen radicals, antioxidant enzyme activity, proline content, and gene transcript levels in oat seeds with different moisture contents (MCs; 4, 16, and 28% w/w) during storage for 0, 6, and 12 months (CK, LT-6, and LT-12 treatments, respectively) at 4°C. The germination percentage decreased significantly with higher seed MCs and longer storage duration. The concentrations of superoxide radical and hydrogen peroxide increased with seed MC increasing. The activities of catalase (CAT), ascorbate peroxidase (APX), and superoxide dismutase (SOD) may have had a complementary or interacting role to scavenge reactive oxygen species. As the storage duration extended, the proline content decreased in seeds with 4 and 16% MC and increased in 28%. These findings suggest that proline played the main role in adaptation to oxidative stress in seeds with higher MC (28%), while antioxidant enzymes played the main role in seeds with lower MCs (4%, 16%). In the gene transcript analyses, SOD1 transcript levels were not consistent with total SOD activity. The transcript levels of APX1 and CAT1 showed similar trends to those of APX and CAT activity. The transcript levels of P5CS1, which encodes a proline biosynthetic enzyme, increased with seed MC increasing in CK. Compared with changing of proline content in seeds stored 12 months, PDH1 transcript levels showed the opposite trend and maintained the lower levels in seeds of 16 and 28% MCs. The transcript level of P5CS1 was significantly affected by MC, and PDH1 could improve stress resistance for seed aging and maintain seed vigor during long-term storage.

New series of avenanthramides in oat seed.

Avenanthramides are characteristic constituents of oat seeds. We analyzed the methanol extract of oat seeds by HPLC and detected three compounds 1, 2, and 3 eluted at retention times similar to avenanthramides. The three compounds were purified by column chromatography and HPLC. Spectroscopic analyses of 1, 2, and 3 suggested that they are amides of 4,5-dihydroxyanthranilic acid with caffeic, p-coumaric, and ferulic acids, respectively. Their identities were confirmed by comparing spectra and chromatographic behavior with compounds synthesized from 4,5-dihydroxyanthranilic acid and N-hyrdroxysuccinimide esters of hydroxycinnamic acids. LC-MS/MS analysis with multiple reaction monitoring showed that the amounts of 1, 2, and 3 were 16.5-26.9% of corresponding avenanthamides with 5-hydroxyanthranilic acid. Compounds 1, 2, and 3 showed stronger 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activity than the corresponding avenanthramides with 5-hydroxyanthranilic acid, indicating the involvement of 4,5-dihydroxyanthranilic acid moiety in the scavenging of DPPH radicals.

Relative Canopy Height Influences Wild Oat (Avena fatua) Seed Viability, Dormancy, and Germination

The environment in which a plant grows (maternal environment) can affect seed viability, germination, and dormancy. We assessed the effects of maternal environment on wild oat seed viability, germination, dormancy, and pathogen infection by collecting and analyzing wild oat seed from above and below a barley canopy at three field sites in Montana. The viability of wild oat seed collected below a crop canopy was consistently less than it was for seed from the overstory but varied among sites and years. Reductions in viability because of relative canopy position ranged from 10% to 30%. Effects of position relative to crop canopy on weed seed germination/dormancy rates varied by site and suggest that the direction and magnitude of the effects of maternal environment on dormancy depend on environmental conditions. These effects may be driven by crop competition or by changes in seed pathogen pressure or both. Seven species each of fungi and bacteria were isolated from wild oat seeds. The only fungi causing reductions in seed viability (15%) was isolated from understory seeds, and several bacteria from both overstory and understory sources reduced seed germination. Results suggest that, in addition to the known weed-suppressive effects of using taller or earlier emerging varieties of crops, such crops can reduce weed spread through effects on weed seed demography because weeds growing beneath the crop canopy produce a reduced amount of viable seed that is less likely to germinate in the following year.

Analysis and annotation of the hexaploid oat seed transcriptome

BackgroundNext generation sequencing provides new opportunities to explore transcriptomes. However, challenges remain for accurate differentiation of homoeoalleles and paralogs, particularly in polyploid organisms with no supporting genome sequence. In this study, RNA-Seq was employed to generate and characterize the first gene expression atlas for hexaploid oat.ResultsThe software packages Trinity and Oases were used to produce a transcript assembly from nearly 134 million 100-bp paired-end reads from developing oat seeds. Based on the quality-parameters employed, Oases assemblies were superior. The Oases 67-kmer assembly, denoted dnOST (de novo Oat Seed Transcriptome), is over 55 million nucleotides in length and the average transcript length is 1,043 nucleotides. The 74.8× sequencing depth was adequate to differentiate a large proportion of putative homoeoalleles and paralogs. To assess the robustness of dnOST, we successfully identified gene transcripts associated with the biosynthetic pathways of three compounds with health-promoting properties (avenanthramides, tocols, β-glucans), and quantified their expression.ConclusionsTo our knowledge, this study provides the first direct performance comparison between two major assemblers in a polyploid organism. The workflow we developed provides a useful guide for comparable analyses in other organisms. The transcript assembly developed here is a major advance. It expands the number of oat ESTs 3-fold, and constitutes the first comprehensive transcriptome study in oat. This resource will be a useful new tool both for analysis of genes relevant to nutritional enhancement of oat, and for improvement of this crop in general.

A developmental profile of tocol accumulation in oat seeds

Oats are a good source of many vitamins and minerals, including compounds that collectively constitute vitamin E, the tocols. Tocols are comprised of two subgroups, tocopherols and tocotrienols. Due to their potent antioxidant properties, attention has been given to the health benefits of tocols in oats. However, little is known about developmental aspects of their accumulation. Moreover, aside from their role in protecting membranes from oxidative damage, their possible physiological roles in planta have largely gone uninvestigated. In this study, we quantified tocol accumulation at five time points during oat seed development, and also compared tocol concentration and composition in the whole seed both to endosperm and embryos at a late stage of seed development. The temporal pattern of accumulation of the tocol subgroups was different. Both tocotrienols and tocopherols steadily increased over the course of seed development; however, tocotrienol progression was sigmoidal and tocopherol linear. By the end of seed development, tocotrienols were the most abundant tocol both in whole seed and in seed with embryos removed. In contrast, embryos contained higher concentrations of tocopherols than tocotrienols late in seed development. Differences in both temporal and spatial distribution during seed development suggest distinct roles for tocotrienols and tocopherols.