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1.
Hansen LM 《Journal of agricultural and food chemistry》2006,54(4):1031-1035
Partial host-plant resistance could make a substantial contribution to reducing the damage caused by economically important grain aphids and, therefore, to reduced insecticide use. Naturally occurring hydroxamic acids, in particular 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA), have been shown to be involved in the resistance of cereals to insects. DIMBOA is unstable in aqueous solutions and has been reported to decompose to 6-methoxybenzoxazolin-2-one (MBOA). MBOA was tested on grain aphids living on artificial diet incorporated with MBOA. From 0 to 0.1 mM, the intrinsic rate of increase (rm) increased. From 0.1 to 0.3 it decreased by 73%. The rm was calculated to be 0 at 1.0 mM. Consequently, even low concentrations of MBOA may reduce the aphid multiplication to a level below the economic damage threshold. Therefore, it is possible to breed wheat varieties with a sufficiently high content of DIMBOA to decrease grain aphid populations. 相似文献
2.
The hydroxamic acid 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA) and the benzoxazolinones benzoxazolin-2-one (BOA) and 6-methoxybenzoxazolin-2-one (MBOA) have been identified as important allelochemicals in wheat. This study examines the possibility of exploiting the allelopathic properties of wheat as a weed control strategy by cultivating wheat as a precrop and incorporating plant residues into the soil before the next crop is sown. Different wheat varieties were cultivated in field plots during two seasons in both conventional and organic farming systems. Plants were sampled at various growth stages, and their contents of DIMBOA, MBOA, and BOA were determined by chemical analyses. The wheat samples were incorporated into soil, and the effect on germination and growth of 12 different weed species was examined in pot experiments under controlled conditions. In some cases significant effects were obtained, but the results were inconsistent and the effects were not correlated to the content of DIMBOA, MBOA, and BOA in the incorporated wheat plants. ED50 doses of the pure compounds were estimated in dose-response experiments in Petri dishes, and these turned out to be much higher than the predicted maximum concentrations of DIMBOA, MBOA, and BOA in the soil water following incorporation. The study shows that a prerequisite for exploiting the incorporation of wheat residues as a weed control strategy is the development of wheat varieties with an increased content of allelochemicals. 相似文献
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Etzerodt T Nielsen ST Mortensen AG Christophersen C Fomsgaard IS 《Journal of agricultural and food chemistry》2006,54(4):1075-1085
To deduce the structure of the large array of compounds arising from the transformation pathway of 6-methoxybenzoxazolin-2-one (MBOA), the combination of isotopic substitution and liquid chromatography analysis with mass spectrometry detection was used as a powerful tool. MBOA is formed in soil when the cereal allelochemical 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA) is exuded from plant material to soil. Degradation experiments were performed in concentrations of 400 microg of benzoxazolinone/g of soil for MBOA and its isotopomer 6-trideuteriomethoxybenzoxazolin-2-one ([D3]-MBOA). Previously identified metabolites 2-amino-7-methoxyphenoxazin-3-one (AMPO) and 2-acetylamino-7-methoxyphenoxazin-3-one (AAMPO) were detected. Furthermore, several novel compounds were detected and provisionally characterized. The environmental impact of these compounds and their long-range effects are yet to be discovered. This is imperative due to the enhanced interest in exploiting the allelopathic properties of cereals as a means of reducing the use of synthetic pesticides. 相似文献
5.
Fomsgaard IS Mortensen AG Idinger J Coja T Blümel S 《Journal of agricultural and food chemistry》2006,54(4):1086-1092
Benzoxazinones, such as 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA) and 2,4-dihydroxy-1,4-benzoxazin-3-one (DIBOA), and benzoxazolinones, such as 6-methoxy-2-benzoxazolinone (MBOA) and 2-benzoxazolinone (BOA), are biologically active secondary metabolites found in cereals. Because these compounds could be exploited as part of a strategy for reducing the use of synthetic pesticides, ecotoxicological tests were performed recently. In this paper, the transformation of the compounds in the test environment of the ecotoxicological tests was studied. DIMBOA was degraded and partly transformed to MBOA during the period of ecotoxicological testing of the compounds. During testing of MBOA on Poecilus cupreus test media the analysis showed that at the initial concentrations of 2 and 10 mg kg(-1) no MBOA was left after 45 days of testing, but the metabolite 2-amino-phenoxazin-3-one (AMPO) was formed. During testing of BOA on both Folsomia candida and Poecilus cupreus the more biologically active compound 2-amino-phenoxazin-3-one (APO) was formed. Thus, the ecotoxicological test results on MBOA and BOA were partly due to the microbial transformation of the compounds during the time of testing. 相似文献
6.
Despite an increase in the understanding of the soybean isoflavones involved in root-colonizing symbioses, relatively little is known about their levels in the rhizosphere and their interactions with the soil microbial community. Based on a 13-year experiment of continuous soybean monocultures, in the present study we quantified isoflavones in the soybean rhizosphere and analyzed the soil microbial community structure by examining its phospholipid fatty acid (PLFA) profile. Two isoflavones, daidzein (7, 4′-dihydroxyisoflavone) and genistein (5,7,4′- trihydroxyisoflavone), were detected in the rhizosphere soil of soybean plants, with the concentrations in the field varying with duration of mono-cropping. Genistein concentrations ranged from 0.4 to 1.2 μg g−1 dry soil over different years, while daidzein concentrations rarely exceeded 0.6 μg g−1 dry soil. PLFA profiling showed that the signature lipid biomarkers of bacteria and fungi varied throughout the years of the study, particularly in mono-cropping year 2, and mono-cropping years 6-8. Principal component analysis clearly identified differences in the composition of PLFA during different years under mono-cropping. There was a positive correlation between the daidzein concentrations and soil fungi, whereas the genistein concentration showed a correlation with the total PLFA, fungi, bacteria, Gram (+) bacteria and aerobic bacteria in the soil microbial community. Both isoflavones were easily degraded in soil, resulting in short half-lives. Concentrations as small as 1 μg g−1 dry soil were sufficient to elicit changes in microbial community structure. A discriminant analysis of PLFA patterns showed that changes in microbial community structures were induced by both the addition of daidzein or genistein and incubation time. We conclude that daidzein and genistein released into the soybean rhizosphere may act as allelochemicals in the interactions between root and soil microbial community in a long-term mono-cropped soybean field. 相似文献
7.
农村混合污水灌溉对小麦生长及其根际微环境的影响 总被引：1，自引：0，他引：1
以土柱模拟试验为基础,利用不同稀释倍数的农村混合污水(污水∶清水为1∶0,1∶1,0∶1)灌溉小麦,进而研究农村混合污水灌溉(WG)对小麦生长、根际土壤养分、酶活性和微生物多样性的影响。结果表明,污水含量的高低对小麦生长及根际土壤养分、酶活性和微生物多样性有一定的影响。与清水灌溉(CK)相比,WG处理后:(1)小麦株高、径粗、鲜重和干重均显著高于CK(P0.05),小麦叶片叶绿素a、叶绿素b和总叶绿素含量显著增加(P0.05);(2)小麦根际土壤除有机质含量增加16.42%外,pH、土壤全氮、全钾、全磷、速效磷、速效钾和碱解氮含量及综合肥力均降低(0.95%～16.79%),且速效钾含量降低较为显著(P0.05);(3)小麦根际土壤酸性磷酸酶、脲酶和转化酶活性均显著高于CK(P0.05),过氧化氢酶活性显著降低(P0.05);(4)由Shannon、Ace、Chao、Coverage、Simpson指数及细菌和真菌在genus水平上的微生物群落结构分布可知,小麦根际土壤细菌多样性降低,真菌多样性增加。同时,改变了小麦根际土壤细菌和真菌在genus水平上优势种的相对丰度,但细菌优势种的种类没有发生改变,真菌优势种的种类发生改变。研究结果可为示范区农村混合污水灌溉模式的研究提供有力的理论依据。 相似文献
8.
Macías FA Oliveros-Bastidas A Marín D Castellano D Simonet AM Molinillo JM 《Journal of agricultural and food chemistry》2005,53(3):554-561
Wheat (Triticum aestivum L.) has been found to possess allelopathic potential and studies have been conduced to apply wheat allelopathy for biological weed control. 2,4-Dihydroxy-(2H)-1,4-benzoxazin-3(4H)-one (DIBOA) is a common product found in wheat, corn, and rye exudates and it can be released to the environment by that way. In this report, the stability of DIBOA is studied in two soils from crop lands of wheat cv. Astron and cv. Ritmo. These varieties were selected by their concentrations of DIBOA and 2,4-dihydroxy-7-methoxy-(2H)-1,4-benzoxazin-3(4H)-one (DIMBOA) from aerial parts and by the bioactivities of their aqueous extracts in the growth of wheat coleoptile sections. The degradation rate of DIBOA in these soils was measured in laboratory tests during 90 h by high-pressure liquid chromatography methods. These analyses demonstrate that DIBOA was transformed primarily into 2-benzoxazolinone (BOA). This transformation was similar in both soil types with an average half-life of 43 h. The degradation studies for BOA show its biotransformation to 2-aminophenoxazin-3-one (APO) with a half-life of 2.5 days. Therefore, BOA is an intermediate product in the biotransformation from DIBOA to APO in these wheat crop soils and is consistent with previous findings. APO was not degraded after three months in soil, suggesting that its degradation rate in soil is very slow. 相似文献
9.
SHENTU Jia-Li HE Zhen-Li ZENG Yan-Yan HE Shan-Ying DU Shao-Ting SHEN Dong-Sheng 《土壤圈》2014,24(4):553-562
The effects of root activity on microbial response to cadmium （Cd） loading in the rhizosphere are not well understood. A pot experiment in greenhouse was conducted to investigate the effects of low Cd loading and root activity on microbial biomass and community structure in the rhizosphere of pakchoi （Brassica chinensis L.） on silty clay loam and silt loamy soil. Cd was added into soil as Cd（NO3）2 to reach concentrations ranging from 0.00 to 7.00 mg kg-1. The microbial biomass carbon （MBC） and community structure were affected by Cd concentration, root activity, and soil type. Lower Cd loading rates （〈 1.00 mg kg-1） stimulated the growth of pakchoi and microorganisms, but higher Cd concentrations inhibited the growth of microorganisms. The content of phospholipid fatty acids （PLFAs） was sensitive to increased Cd levels. MBC was linearly correlated with the total PLFAs. The content of general PLFAs in the fungi was positively correlated with the available Cd in the soil, whereas those in the bacteria and actinomycetes were negatively correlated with the available Cd in the soil. These results indicated that fungi were more resistant to Cd stress than bacteria or actinomycetes, and the latter was the most sensitive to Cd stress. Microbial biomass was more abundant in the rhizosphere than in the bulk soil. Root activity enhanced the growth of microorganisms and stabilized the microbial community structure in the rhizosphere. PLFA analysis was proven to be sensitive in detecting changes in the soil microbial community in response to Cd stress and root activity. 相似文献
10.
崇明西红花根际土壤和球茎微生物多样性分析 总被引：1，自引：0，他引：1
为研究崇明西红花栽培地根际土壤和球茎中微生物多样性,采用Illumina MiSeq高通量测序技术对其微生物群落组成进行了比对分析。结果表明,西红花根际土壤和球茎中细菌和真菌在门类水平上菌群类别差异不显著,但在丰富度和多样性方面根际土壤明显高于球茎;在属和种水平上差异显著;在种水平上,根际土壤或球茎均有各自特有的细菌或真菌,且具有较高的相对丰度。西红花致病真菌瓶霉(Phialophora)和背芽突霉(Cadophora)在崇明西红花球茎大量存在。因此,推测西红花病害发生,除与土壤菌群相关外,与其内生细菌和真菌也紧密相关。本研究结果初步分析了崇明栽培地西红花根际土壤和球茎中微生物多样性及群落结构组成,为进一步筛选合适的崇明西红花栽培地土壤和种球杀菌剂提供了理论依据。 相似文献
11.
Before natural plant allelochemicals can be exploited as biological pesticides against weeds and for disease control, more than the effect on target organisms needs to be known. This study presents results of aquatic biotests using four organisms, namely, a water flea, a freshwater alga, a soil alga, and a luminescent bacterium. The tested substances were 10 benzoxazinone derivatives, 3 of them known to be wheat allelochemicals, benzoxazolin-2(3H)-one (BOA), 6-methoxybenzoxazolin-2(3H)-one (MBOA), and 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3-one (DIMBOA), and 7 identified degradation intermediates and metabolites. For comparison, two commercial pesticide formulations (BAS, Betanal) were tested by applying the same set of biotests. The data set produced could be seen as an ecotoxicological evaluation for effects of allelochemicals against nontarget organisms and as a base for further risk assessment. 相似文献
12.
Rasit Asiloglu Hiroki Honjo Norikuni Saka Susumu Asakawa Jun Murase 《Soil Science and Plant Nutrition》2013,59(5):761-768
Rice roots provide a specific habitat for microorganisms in the rhizosphere of a submerged field through supply of oxygen and organic matter. Many studies have focused on the microbial community in the rice rhizosphere, but less is still known about the microeukaryotic community structure of rice rhizosphere. This study explored the microeukaryotic community structure of a rice rhizosphere through denaturing gradient gel electrophoresis (DGGE) targeting 18S rRNA gene. The rice roots and the rhizosphere soil samples, which were collected from a field under rice-wheat rotation system, were separately analyzed. To characterize the rice rhizosphere-specific community, the bulk soil of rice field and the wheat rhizosphere samples were also examined. DGGE fingerprints showed that the microeukaryotic community of rice roots were distinct from the community of the bulk soil and showed a temporal shift with the growth stage. The rhizosphere soil community was distinct from the root and bulk soil communities, but this could be explained by that the root and bulk soil communities were shared in the rhizosphere. The rice rhizosphere community was also distinct from those in the wheat rhizosphere. Microeukaryotes that characterized the rice rhizosphere (roots and the rhizosphere soil) community could be affiliated to Polymyxa, flagellates, and oomycetes, which suggested that microeukaryotes with various ecological roles, e.g., parasites, bacterial grazers, and decomposers, inhabit the rice rhizosphere. The results showed that the rice root and its growth stages are key factors shaping the microeukaryotic community structure in the rhizosphere. 相似文献
13.
基于高通量测序研究草莓根际微生物群落结构和多样性 总被引：11，自引：3，他引：8
研究草莓根际土壤微生物群落组成和结构,对健康草莓土壤生态系统的构建和保持具有重要意义。以不同地区草莓根际土壤为研究样本,利用MiSeq平台Illumina第二代高通量测序技术并结合相关生物信息学分析土壤细菌16S rRNA基因V4+V5区域和真菌ITS1+ITS2区域的丰富度和多样性指数以及群落结构。结果表明:从15个草莓根际土壤样本中获得4554个细菌分类操作单元OTU和1298个真菌OTU,草莓根际土壤的优势细菌门为变形菌门、厚壁菌门、放线菌门、酸杆菌门和绿弯菌门,主要的优势细菌属有16种;优势真菌门为子囊菌门、接合菌门和担子菌门,主要的优势真菌属有8种。冗余分析(RDA)显示,全氮和pH对土壤微生物群落结构的影响最大,共解释了61%的群落变化,各因子的贡献率大小依次为土壤全氮pH有效磷全钾全磷有机质速效钾碱解氮;相关性分析也表明,土壤理化指标均与不同优势菌门存在密切的相关关系。本研究结果加深了对草莓根际微生物群落结构和多样性的认识,为深入研究草莓根际微生物多样性及功能与环境因子之间的关系提供了借鉴。 相似文献
14.
Growth,P uptake and rhizosphere properties of wheat and canola genotypes in an alkaline soil with low P availability 总被引：1，自引：0，他引：1
Zakaria Solaiman Petra Marschner Dongmei Wang Zed Rengel 《Biology and Fertility of Soils》2007,44(1):143-153
The aim of the present study was to assess the role of soil type on growth, P uptake and rhizosphere properties of wheat and
canola genotypes in an alkaline soil with low P availability. Two wheat (Goldmark and Janz) and two canola genotypes (Drum
and Outback) were grown in a calcareous soil (pH 8.5) at two P levels [no P addition (0P) or addition of 200 mg kg−1 P as Ca3(PO4)2 (200P)] and harvested at flowering or maturity. Shoot and root dry weight, root length and shoot P content were greater in
the two canola genotypes than in wheat. There were no consistent differences in available P, microbial P and phosphatase activity
in the rhizosphere of the different genotypes. Shoot P content was significantly positively correlated with root length, pH
and phosphatase activity in the rhizosphere. The microbial community composition, assessed by fatty acid methylester analysis,
of the canola genotypes differed strongly from that of the wheat genotypes. The weight percentage bacterial fatty acids, the
bacteria/fungi (b/f) ratio and the diversity of fatty acids were greater in the rhizosphere of the canolas than in the rhizosphere of the wheat
genotypes. In contrast to the earlier studies in an acidic soil, only small differences in growth and P uptake between the
genotypes of one crop were detected in the alkaline soil used here. The results confirmed the importance of root length for
P uptake in soils with low P availability and suggest that the rhizosphere microbial community composition may play a role
in the better growth of the canola compared to the wheat genotypes. 相似文献
15.
Mogensen BB Krongaard T Mathiassen SK Kudsk P 《Journal of agricultural and food chemistry》2006,54(4):1023-1030
Three varieties of winter wheat (Triticum aestivum) were grown in both conventional and organic farming systems. The contents of the benzoxazinone derivatives 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA), 2-beta-d-glucopyranosyloxy-4-hydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA-Glc), 6-methoxybenzoxazolin-2-one (MBOA), 2-hydroxy-7-methoxy-1,4-benzoxazin-3-one (HMBOA), benzoxazolin-2-one (BOA), and 2-hydroxy-1,4-benzoxazin-3-one (HBOA) were analyzed at five growth stages (BBCH 9-10, 12, 21, 31, and 53). Major differences were found between the varieties, with Stakado exhibiting the highest contents. In contrast, only minor and erratic differences were found between the two farming systems, suggesting that the inherent differences in the content of benzoxazinone derivatives of the varieties were not significantly affected by the use of pesticides and synthetic fertilizers. The concentration of benzoxazinone derivatives in the foliage was considerably higher at the early growth stages than later in the growing season, with DIMBOA being the most abundant of the benzoxazinone derivatives. An increase in the concentration was observed in early spring compared to late autumn, suggesting that plants synthesized benzoxazinone derivatives at the commencement of growth in early spring. The concentrations in the roots were considerably lower than in the foliage at the early growth stages but remained relatively constant over time, resulting in a higher concentration than in the foliage at the late growth stages. The results are discussed in relation to previous findings that predominantly originate from experiments done under controlled conditions in either growth cabinets or greenhouses. 相似文献
16.
Jeffrey S. Buyer John R. Teasdale Inga A. Zasada Jude E. Maul 《Soil biology & biochemistry》2010,42(5):831-841
Soil and rhizosphere microbial communities in agroecosystems may be affected by soil, climate, plant species, and management. The management and environmental factors controlling microbial biomass and community structure were identified in a three-year field experiment. The experiment consisted of a tomato production agroecosystem with the following nine treatments: bare soil, black polyethylene mulch, white polyethylene mulch, vetch cover crop, vetch roots only, vetch shoots only, rye cover crop, rye roots only, and rye shoots only. The following hypotheses were tested: (1) Temperature and moisture differences between polyethylene-covered and cover-cropped treatments are partly responsible for treatment effects on soil microbial community composition, and (2) Different species of cover crops have unique root and shoot effects on soil microbial community composition. Microbial biomass and community composition were measured by phospholipid fatty acid analysis. Microbial biomass was increased by all cover crop treatments, including root only and shoot only. Cover cropping increased the absolute amount of all microbial groups, but Gram-positive bacteria decreased in proportion under cover crops. We attribute this decrease to increased readily available carbon under cover-cropped treatments, which favored other groups over Gram-positive bacteria. Higher soil temperatures under certain treatments also increased the proportion of Gram-positive bacteria. Vetch shoots increased the amount and proportion of Gram-negative bacteria, fungi, and arbuscular mycorrhizal fungi in the rhizosphere of tomato plants. The imposed treatments were much more significant than soil temperature, moisture, pH, and texture in controlling microbial biomass and community structure. 相似文献
17.
The influence of inoculation of olive trees with arbuscular mycorrhizal (AM) fungi, Glomus (G) intraradices, on microbial communities and sugar concentrations, were examined in rhizosphere of olive trees (Olea europaea L.). Analyses of phospholipid and neutral lipid fatty acids (PLFA and NLFA, respectively) were then used to detect changes in microbial community structure in response to inoculation of plantlets with G. intraradices.Microscopic observations studies revealed that the extraradical mycelium of the fungus showed formation of branched absorbing structures (BAS) in rhizosphere of olive tree. Root colonization with the AM fungi G. intraradices induced significant changes in the bacterial community structure of olive tree rhizosphere compared to non-mycorrhizal plants. The largest proportional increase was found for the fatty acid 10Me18:0, which indicated an increase in the number of actinomycetes in mycorrhizal rhizosphere soil, whereas the PLFAs i15:0, a15:0, i16:0, 16:1ω7 and cy17:0 which were used as indicators of bacteria decreased in mycorrhizal treatment compared to non-mycorrhizal control treatment. A highest concentration of glucose and trehalose and a lowest concentration of fructose, galactose, sucrose, raffinose and mannitol were detected in mycorrhizal rhizosphere soil. This mycorrhizal effect on rhizosphere communities may be a consequence of changes in characteristics in the environment close to mycorrhizal roots. 相似文献
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小麦、毛苕子与黄瓜轮作对土壤微生态环境及产量的影响 总被引：12，自引：0，他引：12
采用常规方法及PCR-DGGE技术对土壤速效养分含量、土壤酶活性和微生物群落结构多样性以及黄瓜产量进行分析,以探究小麦、毛苕子与黄瓜轮作对黄瓜土壤微生态环境及产量的影响。结果表明,不同轮作处理均显著地提高了黄瓜产量,有效地改善了土壤微生态环境。其中小麦-黄瓜轮作黄瓜产量极显著高于对照(p<0.01),增产28.04%,其多酚氧化酶、过氧化氢酶及脲酶活性总体较高。毛苕子-黄瓜处理增产16.78%,并增加了土壤养分含量,转化酶活性较高,极显著高于对照(p<0.01)。DGGE结果表明,轮作有助于根际土壤细菌种类的增多及结瓜后期真菌种类的减少,其中毛苕子-黄瓜处理的影响更为明显。小麦-黄瓜轮作对土壤真菌与定植后30 d土壤细菌群落结构具有一定的影响。总之,小麦、毛苕子与黄瓜轮作有利于缓解黄瓜连作障碍,改善土壤微生态环境,提高黄瓜产量。 相似文献