TRI12 based quantitative real-time PCR assays reveal the distribution of trichothecene genotypes of F. graminearum and F. culmorum isolates in Danish small grain cereals

Quantitative real-time PCR assays, based on polymorphisms in the TRI12 gene of the trichothecene pathway, were developed to identify and quantify the trichothecene genotypes producing 3-acetyl-deoxynivalenol (3ADON), 15-acetyl-deoxynivalenol (15ADON) or nivalenol (NIV) in the Fusarium graminearum species complex, Fusarium culmorum, Fusarium cerealis and Fusarium pseudograminearum. These assays were applied on a total of 378 field samples of cereal grain of wheat, barley, triticale, rye and oats collected from 2003 to 2007 to study the trichothecene genotype composition in Danish cereals. The three genotypes, 3ADON, 15ADON and NIV were found in all five cereal species, great annual variation in the occurrence of the trichothecene genotypes was evident with considerable variation between the samples. 3ADON was the dominant genotype in barley, triticale, rye and oats while 15ADON was most dominant in wheat. The NIV genotype was found at low levels in most samples. Study of genotype composition within the Danish F. graminearum and F. culmorum population was based on principal component analysis (PCA). PCA revealed that the dominating genotype of F. graminearum in wheat is 15ADON. For barley, the PCA analysis indicated that the F. graminearum population consisted of all three genotypes, and in triticale, the F. graminearum population consisted mainly of 15ADON genotype. F. culmorum/F. cerealis showed correlation to the NIV genotype in wheat and triticale but not in barley. F. culmorum/F. cerealis also showed some correlation to 3ADON especially in wheat and triticale. Selected wheat and barley samples from 1957 to 2000 showed low amounts of F. graminearum and F. culmorum in general but with a dominance of the 3ADON genotype. 15ADON was not detected in these samples, except for very low amounts in the sample representing the years from 1997 to 2000. Detection of low amounts of the 15ADON genotype in these historical samples and the relatively high amounts of 15ADON genotype in 2003 and following years correspond well with the occurrence of F. graminearum and indicates that the 15ADON genotype was introduced along with F. graminearum around 2000. The amounts of the 3ADON and 15ADON genotypes correlated well with the total amount of DON whereas the amounts of NIV genotype correlated well with the amount of NIV in wheat and triticale but not in barley where the results indicate that Fusarium poae may also contribute to the NIV content.     

小麦赤霉病源呕吐毒素的合成、检测及防控

赤霉病是主要由禾谷镰刀菌侵染小麦、大麦和其他小谷类作物而造成作物减产的世界性病害。小麦赤霉病发病需要高温和高湿的环境条件,感染程度及发病范围主要由寄主自身的抗性决定,对粮食产业以及人类健康的危害主要来源于籽粒中积累的呕吐毒素(deoxynivalenol, DON)。赤霉病需要多层次、全流程的防治,而降低DON毒素的危害是防治赤霉病需要重点突破的环节。本文概述了DON的合成过程、致病机制、检测方法和脱毒策略,并提出防治赤霉病的思路,重点挖掘与DON毒素诱导、运输和转化相关的基因资源,为通过生物育种途径培育DON低积累小麦品种、减少DON危害提供参考。     

Population growth of the khapra beetle,Trogoderma granarium Everts (Coleoptera: Dermestidae) on different commodities

We evaluated the population growth of the khapra beetle, Trogoderma granarium Everts (Coleoptera: Dermestidae) on different grains, cracked wheat containment categories and amylaceous materials by conducting three series of laboratory bioassays. In the first series, peeled barley, whole (raw) barley, peeled oats, whole (raw) oats, peeled rice, rough rice, rye, triticale and hard wheat were tested. In the second series, six cracked wheat containment categories were tested: wheat containing intact kernels only (0% cracked kernels), wheat containing 5% cracked kernels and 95% intact kernels, wheat containing 10% cracked kernels and 90% intact kernels, wheat containing 25% cracked kernels and 75% intact kernels, wheat containing 50% cracked kernels and 50% intact kernels and wheat containing 100% cracked kernels. In the third series, the following amylaceous commodities were tested: hard wheat (intact kernels), whole oat flakes, maize flour, whole barley flour, pasta, white soft wheat flour, whole soft wheat flour, white hard wheat flour, whole hard wheat flour, whole rye flour and semolina. Significantly more dead adults were found on wheat than on peeled barley, maize, whole oats, rough rice and rye. Significantly more larvae alive were found on wheat and triticale, than on the other grains, with the exception of oats, both whole and peeled. The increase of the percentage of cracked wheat kernels increased population growth, except in the case of 10% cracked wheat kernels. In vials that contained 100% cracked wheat kernels, 584.1 individuals per vial were found, which was 3.7 times more than the respective number of larvae alive in vials with intact wheat kernels only. Significantly more dead adults were found on whole barley flour than on the other commodities. More than 1213 larvae per vial were recorded on whole barley flour, which was 1.3–15 times higher than the other commodities. The lowest number of larvae alive was found on pasta, followed by the white soft wheat flour. The findings of the present work show that some commodities are more prone to spread T. granarium than others, a fact which should be seriously taken into account in international trade of grains and related amylaceous products.     

Natural occurrence of scirpentriol in cereals infected by Fusarium species.

Wheat, barley and oat grain samples naturally contaminated with Fusarium spp. were analysed for the presence of scirpentriol (STO). This toxin was detected in 1, 37 and 8% of 248 wheat, 32 barley and 99 oat grain samples, respectively, and the maximum concentration was 83 microg x kg(-1). Samples of wheat and oat grain with visible scab symptoms were also analysed, and STO (mean level 255 microg x kg(-1)) was detected only in oat samples infected with F. sporotrichioides and F. poae as the dominant species. We analysed 15 barley samples that were subdivided based on seed size into fractions of <2.5 and > 2.5 mm in diameter. The smaller kernels contained an average 94% of the STO in the samples (in kernel fraction > 2.5 mm 28 microg x kg(-1), <2.5 mm 297 microg x kg(-1)). In oats, STO levels were highest in the chaff, lower in the stalk's apical internode and lowest in the grain.     

Influence of commodity on the population growth of the larger grain borer,Prostephanus truncatus (Horn) (Coleoptera: Bostrychidae)

In this study, we compared different amylaceous commodities for their suitability for population growth of the larger grain borer, Prostephanus truncatus (Horn) (Coleoptera: Bostrychidae), which is an important pest of stored maize in the tropics. In this context, we conducted three different series of tests. In the first test, we compared whole grains: whole barley, peeled barley, maize, whole oats, peeled oats, peeled rice, rough rice, rye, triticale, and wheat. Only maize was found suitable for P. trunctatus to reproduce and significantly increase its population, but there were certain commodities where surviving adults were found. In the second series of tests, we evaluated the percentage of cracked maize kernels on P. truncatus population growth. In this test, we found that the numbers of alive P. truncatus adults in the vials that contained 100% cracked kernels was higher than these with lower percentages of cracked kernels (5–50%) or no cracked kernels (0%). Finally, in the third series of tests, we compared eleven different types of amylaceous commodities with maize. These commodities were: whole maize (whole kernels), whole oat flakes, maize flour, whole barley flour, pasta, white soft wheat flour, whole soft wheat flour, white hard wheat flour, whole hard wheat flour, whole rye flour, and semolina. The results indicated that only whole maize and maize flour were suitable for P. truncatus population growth. Nevertheless, in some of the other commodities tested, there was a low number of adults and immatures that were able to survive 60 days after the incorporation of the parental adults. The results of the present study indicate that from the commodity range tested here, only maize was suitable for P. truncatus population growth. Nevertheless, the marginal numbers of surviving individuals in the non-maize commodities and the role of these substrates as potential “non-preferred food vehicles” that may contribute to further spread of this species should be tested in more detail.     

Species-specific PCR-based assays for the detection of Fusarium species and a comparison with the whole seed agar plate method and trichothecene analysis

Species-specific PCR was used for the identification of nine Fusarium species in pure mycelial culture. A PCR-based method was compared with the whole seed agar plate method and trichothecene analysis for three toxin-producing Fusarium species using 85 grain samples of wheat, barley, oat, corn and rye. A simple SDS-based DNA extraction system followed by potassium acetate precipitation resulted in consistent PCR amplification of DNA fragments from cultures and grain samples. The species-specific PCR assays correctly identified pure cultures of Fusarium avenaceum ssp. avenaceum (9 isolates), Fusarium acuminatum ssp. acuminatum (12 isolates), Fusarium crookwellense (7 isolates), Fusarium culmorum (12 isolates), Fusarium equiseti (11 isolates), Fusarium graminearum (77 isolates), Fusarium poae (10 isolates), Fusarium pseudograminearum (23 isolates), and Fusarium sporotrichioides (10 isolates). Multiplex PCR was developed for the simultaneous detection of F. culmorum, F. graminearum and F. sporotrichioides, the three most important trichothecene producing species in Canada. In grain samples, results of PCR assays for these same three species related well with whole seed agar plate method results and determination of Fusarium trichothecenes. The PCR assay described in this study can be used for routine detection and identification of Fusarium spp. in Canada.     

Strategies for managing Fusarium head blight and deoxynivalenol accumulation in wheat

Many mycotoxigenic fungi infect plant hosts and cause disease in the field. Therefore, control of field infection by these fungi is a critical step in managing mycotoxin accumulation in the harvested product. Fusarium graminearum, also known as Gibberella zeae, is the causal agent of Fusarium head blight (FHB), or scab, in cereals and is also the primary agent responsible for contamination of grain with deoxynivalenol (DON). Research efforts worldwide are devoted to the development of strategies to control field infection of wheat and barley by this pathogen. Strategies include the use of fungicides and biological control agents to protect flowering heads from infection. There is extensive effort in breeding for host resistance to infection and spread of the pathogen within the heads. Scientists are also seeking exogenous traits to introduce into cereals to enhance resistance. Cultural practices are also being examined, primarily as measures to reduce pathogen survival and inoculum production in crop residues. The successes and limitations of these strategies in the management of Fusarium head blight and deoxynivalenol are discussed.     

Fundamental study on the effect of hydrostatic pressure treatment on the bread-making performance of oat flour

The use of sourdough in wheat and rye breads has been extensively studied; however, little is known about its potential effect when baking oat bread. Consequently, the impact of sourdough on oat bread quality was investigated. Two different sourdoughs were prepared from wholegrain oat flour without the addition of starter cultures, by continuous propagation at 28 (SD 28) or 37 °C (SD 37) until the composition of the lactic acid bacteria remained stable. The dominant LAB were identified by sequence analysis of the 16S rDNA isolated from pure cultures. LAB from SD 28 belonged to the species Leuconostoc argentinum, Pedicoccus pentosaceus and Weissella cibaria, while Lactobacillus coryniformis dominated SD 37. The isolated LAB were further used as starter cultures for the production of oat sourdoughs. Fundamental rheology revealed softening of the sourdoughs compared to non-acidified and chemically acidified controls, which could not be attributed to proteolytic activity. Incorporation of oat sourdough into an oat bread recipe resulted in significantly increased loaf-specific volume as well as improved texture, independent of addition level or sourdough type. Overall, the results of this study show that sourdoughs containing lactic acid bacteria isolated from oats have the potential to enhance oat bread quality.     

Application of immunodiffusion in detecting the presence of barley in wheat flour

An immunological method for detection of barley contamination in wheat flour was developed. a rabbit antiserum to barley proteins was tested against different protein concentrations of barley and wheat extracts by the immunodiffusion technique. It was possible to identify with barley a typical precipitin band which is not present with wheat flour. the barley antiserum was then adsorbed by wheat and tested against wheat proteins contaminated with barley proteins at different concentrations. the results indicated that it is possible to detect a contamination of 5 % of barley proteins in wheat proteins. Samples of commercially available barley and wheat flour were also tested on agar plates against the barley anti-serum adsorbed from wheat. Again it was possible to detect a contamination of 5% of barley flour in wheat flour. It appears that this is a simple but specific immunological method suitable for routine testing.     

基于气相色谱定量检测面粉中燕麦粉的添加量

本文采用气相色谱技术获取48个品种燕麦粉、40个品种小麦面粉及105个运用平衡不完全随机区组的试验方法设计得到的燕麦小麦复配粉定量样本的脂肪酸组成信息,分析其棕榈酸、油酸和亚油酸的含量,油酸/亚油酸、棕榈酸/油酸、棕榈酸/亚油酸的比值及相关性;根据燕麦和小麦中脂肪酸组成的相似性确定用于面粉中燕麦粉添加量的定量分析指标,根据脂肪酸含量间的差异性体现不同梯度的燕麦粉添加复配粉中脂肪酸含量的变化趋势,在此基础上建立判别分析三维图及Fisher线性判别函数,直观地呈现出复配粉中各脂肪酸的分布特点,进而对面粉中燕麦粉的添加量进行定量判别。本研究在分析燕麦和小麦中脂肪酸异同点的基础上为燕麦产品安全监测及品质控制提供了一个适用广泛、灵敏度高、可行性强的重要借鉴方法。     

三种粗粮粉体外调节肠道菌群的作用研究

通过在体外模拟构建消化和发酵体系,研究不同来源的三种麸皮(小麦麸皮、黑小麦麸皮和燕麦麸皮)配制成的粗粮粉对肠道菌群调节作用的影响。采用高通量测序技术16S rRNA对肠道菌群的多样性和组成进行分析,结果表明,粗粮粉发酵后微生物多样性降低,肠道菌群组成发生了较大变化,拟杆菌门比例下降,厚壁菌门比例升高,代谢产生的短链脂肪酸含量显著增多(p<0.05);其中,燕麦粗粮粉促进双歧杆菌体外增殖的效果优于其他两组粗粮粉,分别是小麦粗粮粉和黑小麦粗粮粉的1.45和2.14倍。本研究为调制加工性能好、保健价值高的粗粮粉配方提供了理论依据。     

Epidemiology of Fusarium head blight on small-grain cereals

Fusarium head blight (FHB) is one of the most serious diseases affecting wheat and barley worldwide. It is caused by Fusarium graminearum along with F. culmorum, F. avenaceum and other related fungi. These fungi also produce several mycotoxins. Though the disease results in reduced seed quality and yield, the toxins which may accompany the disease are often a more serious problem. Pathogen inoculum is usually very abundant, however production and dispersal of inoculum are weather-sensitive processes. An abundance of colonized substrate (i.e. maize or cereal debris) in a region contributes to airborne inoculum throughout the area. Local residues beneath the cereal crop (i.e. from previous crop) may have a less obvious effect, particularly in regions where long-distance dispersal is likely due to wind conditions. The host is most susceptible to infection at anthesis and shortly thereafter. A warm, moist environment characterized by frequent precipitation or heavy dew is highly favorable to fungal growth, infection and development of disease in head tissues. As the fungus grows, it produces mycotoxins which are water-soluble and may be translocated between tissues or leeched from source tissues. Important epidemiological issues have arisen recently and include an apparent shift in prevalence of Fusarium species on infected heads in Europe toward F. graminearum; and the presence of multiple chemotypes and aggressiveness variants within a species in a region.     

Antioxidant potential of wheat flour chapattis as affected by incorporating barley flour

Whole wheat flour was replaced with whole barley flour at levels of 28, 56 and 84 g/100 g to prepare chapattis and their antioxidant properties were evaluated before and after baking. The total phenolic content (TPC) in wheat flour was 2062 μg ferulic acid equivalents/g, total flavonoid content (TFC) was 966 μg catechin equivalents/g and antioxidant activity was 12.3% and they increased by 57.1, 101 and 22.6%, respectively upon incorporating barley flour at the highest level. Baking significantly decreased the TPC by up to 17.0% and TFC by up to 30.7% however the AOA increased by 13%. Barley flour incorporation significantly increased the reducing power which upon baking showed an insignificant decrease. Polyphenol oxidase (PPO) activity significantly increased by up to 109% upon incorporating barley flour however baking lowered PPO activity by 67.9%. Chapattis containing barley flour can be used to deliver the bioactive components of barley.     

适合糖尿病的几种杂粮主食面条

摘要：研究了不同配方的荞麦面条、燕麦面条和鹰嘴豆面条以及传统的小麦面条对糖尿病大白鼠餐后血糖的影响。大白鼠血糖实验结果是：荞麦面条（荞麦粉40小麦粉60）、燕麦面条（燕麦粉40小麦粉60）和鹰嘴豆面条（鹰嘴豆粉100、谷朊粉10）的血糖曲线下面积增加值分别是6.23mmol.h/l、6.56mmol.h/l和6.60mmol.h/l。其值明显低于纯小麦面条（14.07mmol.h/l）,显著性p<0.05。这表明以荞麦、燕麦和鹰嘴豆为主要原料加工而成的面条比纯小麦面条更适合作为糖尿病人的主食。     

Fatty acid composition of grain from winter and spring sown oats, barley and wheat.

The fatty acid composition of grain has been studied in six varieties of oats, two of wheat and two of barley, sown in pots in an unheated glasshouse in winter and in spring. Differences were found between the species in composition and in their response to sowing date. Oats showed the greatest varietal variation in both total fatty acid (TFA) content and in the proportion of its component fatty acids. The content and degree of unsaturation of the oat TFA was higher in the winter sown than in the spring sown crop. Increases in the TFA content of oats, whether arising from differences in variety or sowing date, were generally followed by an increase in the proportion of oleic acid and a decrease in the proportions of palmitic and linoleic acid in the TFA. Winter sowing, as compared with spring, led to a small, but significant, decrease in the TFA content of barley and an increase in its degree of unsaturation. There were no significant changes in the content or composition of wheat TFA as a result of differences in sowing date. Factors influencing the differences in TFA content and composition between species, varieties and sowing dates are discussed.     

Fatty acids composition and rheology properties of wheat and wheat and white or brown rice flour mixture

Manufacturing of bread from rice flour only presents technological difficulty because the rice is gluten-free and gluten is the most important structure forming protein. By using wheat and rice flour mixture, this problem can be avoided, and end product is enriched by rice-oil constituents. In this paper fatty acids composition, with an emphasis on total saturated, and total unsaturated fatty acids, rheological and baking properties of wheat–rice flour mixture (70:30 w/w) were investigated. The results show that wheat–rice flour mixture has better fatty acids composition with higher content of stearic, arachidic, lignoceric, oleic, and phthalic acids compared to wheat flour. Also, wheat flour did not include myristic, arachidic, lignoceric and linolenic acids, so rice flour addition made fatty acids profile richer as number of constituents is higher, nine instead six. The content of total unsaturated fatty acids content was higher in wheat–brown rice flour mixture than in wheat flour and in wheat–white rice flour mixture. When rice flour was added to wheat flour the rheological properties were changed: flour mixture had less water absorption, less degree of softening, longer development time, higher gelatinization temperature, but better stability and finally, better quality number and group than wheat flour. So, the wheat and rice flour mixture can be considered as a good quality flour and can be used for making good quality wheat-rice bread and cake.     

Developmental and reproductive biology of Oryzaephilus surinamensis (L.) (Coleoptera: Silvanidae) on seven commodities

This study examines the effect of semolina, cracked wheat, maize flour, cracked maize, whole oat flakes, whole barley flour and cracked barley on the developmental and reproductive biology of the saw-toothed grain beetle, Oryzaephilus surinamensis (L.) (Coleoptera: Silvanidae). The pest completed its development at all tested commodities except semolina and cracked wheat, while females did not produce eggs on maize flour and cracked barley. The developmental time of larvae was significantly longer when O. surinamensis fed on whole oat flakes (20.3 days) and whole barley flour (19.2 days) compared with maize flour (16.6 days) or cracked maize (17.2 days). The developmental duration of larvae fed on cracked barley (18.3 days) did not differ significantly when fed on cracked maize or whole barley flour, but it was significantly longer compared to maize flour and significantly shorter compared to whole oat flakes. The tested commodities did not affect the pupal development, which ranged between 4.6 and 4.7 days. The highest fecundity was recorded when O. surinamensis fed on cracked maize (4.8 eggs/female) and whole oat flakes (0.3 eggs/female). The tested commodities also affected the risk of death of O. surinamensis and its mean survival time. The shortest survival time was recorded on cracked wheat (11.1 days) while the longest was on cracked maize and whole oat flakes (37.8 and 42.2 days, respectively). The calculation of demographic parameters was feasible only on cracked maize. The net reproductive rate, the intrinsic rate of increase, the finite rate of increase and the mean generation time were 1.48 females/female, 0.01 females/female/day, 1.01 and 37.1 days, respectively. These results may be useful for improving the knowledge on the biology of this species and its potential spread.     

Cooking quality characterisation of ‘spaghetti’ based on soft wheat flour enriched with oat flour

The cooking quality of pasta based on soft wheat flour and supplemented with three percentages of oat flour was studied. Results showed that oat flour modified deeply the cooking quality of spaghetti in comparison with samples based on only soft wheat flour. These effects were attributed to both starch‐lipid complex formation and presence of β‐glucans that weak gluten network. An increase in optimal cooking time with increase in oat percentages was observed (480 vs. 630 min). Samples enriched with oat flour showed a good‐quality cooking total organic matter (TOM values ranged from 1.4 to 2).     

Fractional extraction of cereal flour proteins

Wheat (Wichita), rye, barley, oat and maize flours were successively extracted with 0.04 m sodium chloride solution (3 × ), water (3 × ), 70% ethanol (3 ×) and 0.1 N acetic acid. The fractions and residues were analysed for nitrogen and subjected to starch-gel electrophoresis. Saline extractions chiefly removed the albumins and globulins of all five cereals. The prolamins of wheat, rye and barley appeared mostly in the three aqueous extracts but also, particularly, those of very low mobility, occurred in the alcoholic solutions. The acetic acid-soluble fractions of wheat, rye and barley were shown by electrophoresis under reducing conditions to be crosslinked by S.S bonds; those of rye and barley showed some characteristic differences from glutenin. Oats and maize were practically devoid of this fraction. Most of the protein of oats and maize was insoluble. Electrophoresis patterns after reduction were obtained from insoluble fractions, though there were differences among the genera. Both overall protein solubility and the quantity of the acetic acid-soluble fraction were correlated with baking quality. The presence of covalent crosslinks other than S.S in glutelin fractions is suspected.     

燕麦添加量对马铃薯复合面条品质特性的影响

以马铃薯和小麦粉为主要原料,采用质构仪、扫描电镜等技术手段,辅以主成分分析和模糊数学等统计方法,研究燕麦粉添加量对马铃薯复合面条的质构特性、微观结构、干燥特性及感官特性的影响。结果表明:随燕麦粉含量的增加,马铃薯复合面条质构主成分咀嚼性因子、黏弹性因子和硬度因子均呈先减小后增大的趋势;其结构致密程度、孔隙率及有效水分扩散系数也呈先减后增的趋势,复合面条干燥特性变差。当燕麦粉含量为10%时,其咀嚼性、黏弹性和硬度最大,结构致密,有效水分扩散系数较大,复合面条感官评定(色泽、外观、口感、食味)达到最佳。