The herbicide flamprop-M-methyl has a new antimicrotubule mechanism of action

BACKGROUND: The herbicidal mode of action of flamprop‐M‐methyl [methyl N‐benzoyl‐N‐(3‐chloro‐4‐fluorophenyl)‐D ‐alaninate] was investigated. RESULTS: For initial characterization, a series of bioassays was used, which indicated a mode of action similar to that of mitotic disrupter herbicides. Cytochemical fluorescence studies, which included monoclonal antibodies against polymerized tubulin, were applied to elucidate effects on mitosis and microtubule assembly in maize roots. When seedlings were root treated with 50 µM of flamprop‐M‐methyl, cell division activity in meristematic root tip cells ceased within 4 h. The compound severely disturbed the orientation of spindle and phragmoblast microtubules, leading to defective spindle and phragmoblast structures. Cortical microtubules were only slightly affected. In late anaphase and early telophase cells, phragmoblast microtubules were disorganized in multiple arrays that hampered regular cell plate deposition in cytokinesis. Microtubules of the spindle apparatus were found attached to chromosomal kinetochores, but did not show regular organization associated with a zone of microtubule‐organizing centres at the opposite ends of the cell. On account of this loss of spindle organization, chromosomes remained in a condensed state of prometaphase or metaphase. Unlike known microtubule disrupter herbicides, flamprop‐M‐methyl and its biologically active metabolite flamprop did not inhibit soybean tubulin polymerization to microtubules in vitro at 50 µM . In contrast, soybean plants responded sensitively to the compounds. CONCLUSION: The results indicate that flamprop‐M‐methyl is a mitotic disrupter herbicide with a new antimicrotubule mechanism of action that affects orientation of spindle and phragmoblast microtubules, possibly by minus‐end microtubule disassembly. Copyright © 2008 Society of Chemical Industry     

MeSA诱导茶树抗叶蝉取食效应的DC-EPG分析

用可视直流刺探电位技术(DC-EPG)记录试虫在3h 内呈现的各种EPG波型。共明确7种波型,根据这些波型确定15个描述叶蝉取食行为的EPG参数,以评判茶树抗叶蝉取食特性。与未诱导茶苗(CK)上叶蝉刺吸行为相比,在0.2、0.4和0.8mmol/L MeSA诱导24h的茶苗上,总刺探次数增加,即n_(ck) =8.30±1.13,n_(0.2)=13.25±3.95,n_(0.4)=15.01±2.68,n_(0.8)=34.50±7.56;非取食刺探时间明显延长,即NP_(ck)=110.97±5.2min, NP_(0.2)=128.39±6.76min, NP_(0.4)=148.35±6.14min, NP_(0.8)=131.94±10.75min;韧皮部取食时间显著减少,即E_(ck)=52.90±2.22min, E_(0.2)=9.08±2.6min, E_(0.4)=8.87±1.44min, E_(0.8)=15.89±2.21min。3个MeSA处理剂量相比较,0.4mmol/L的诱导效应最明显。24h与48h 诱导时间相比,24h的效应较显著。茶树被诱导之后,对叶蝉的取食适合度明显下降,表明产生了一定程度的抗性。     

Identification of a GDSL-motif carboxylester hydrolase from rice bran (Oryza sativa L.)

A major esterase (designated OsEST1) showing high activity using 1-naphthyl acetate as a substrate was identified from rice bran and purified approximately 239-fold to near-homogeniety. The purified enzyme migrated as a single polypeptide band on native and SDS-polyacrylamide gels and had a molecular mass of 25 kDa under denaturing conditions. Analysis of its tryptic peptides by MALDI-TOF-MS and subsequent data mining identified a corresponding cDNA OsEST1 consisting of 714 nucleotides and encoding a 238 amino acid protein. Analysis of its primary sequence indicated that OsEST1 is a GDSL-motif carboxylester hydrolase belonging to the SGNH protein subfamily in containing the putative catalytic triad of Ser¹¹, Asp¹⁸⁷, and His¹⁹⁰. OsEST1 showed the highest catalytic activity at approximately pH 8.0–8.5 and at 45 °C with K_m and V_max values for 1-naphthyl acetate of 172 μM and 63.7 μmol/min/mg protein, respectively. However, OsEST1 showed no activity with triacylglycerol. Alignment of the primary sequence of OsEST1 and other rice GDSL-motif esterases/lipases showed that OsEST1 aligns with a specific family of plant SGNH esterases involved in response to dehydration and cuticle formation. These results suggest that OsEST1 is not a lipase but an esterase activity which has some other function in rice, especially during seed development.     

库尔勒香梨果胶提取工艺的研究

以库尔勒残次香梨为原料,探讨微波辅助法提取果胶的工艺条件,研究了微波功率、微波时间、pH值和液料比对果胶得率的影响。结果表明,功率为400W、pH为3．5、时间为5min和液料比为9：1是提取库尔勒香梨果胶的最佳工艺条件,果胶得率为4．89％。     

食品添加剂果胶的研究进展

果胶是以半乳糖醛酸为基本构成单位的高分子多糖,其基本结构分为半乳糖醛酸富集的平滑型区域和中性糖富集的分枝型区域。果胶由于独特的理化性质及多样的生理功能,在食品、化工、医药等领域被广泛应用。对近年来果胶的化学构造特征及其功能特性与应用的研究进展作了较为系统的分析与综述。     

甲基丁香酚对桔小实蝇雄虫寿命、交配及雌虫繁殖的影响

室内研究了甲基丁香酚（methyl eugenol）对桔小实蝇Bactrocera dorsalis雄虫寿命、一生交配次数及交配后雌虫的产卵量和卵孵化率的影响。结果表明桔小实蝇雄虫可连续、多次交配,喂食过甲基丁香酚的处理组和没有喂食过甲基丁香酚的对照组平均交配次数分别为6.15次和7.43次,最多分别可达13次和15次;雄虫的交配次数与寿命呈直线正相关关系;甲基丁香酚对雄虫寿命、一生交配次数、交配后雌虫的产卵量及卵孵化率无显著影响。本文还对利用甲基丁香酚诱杀雄虫作为一项防控措施的科学性进行了讨论。     

Effect of adjuvants on the rainfastness and performance of tribenuron‐methyl on broad‐leaved weeds

The influence of a non‐ionic surfactant (20% isodecyl alcohol ethoxylate plus 0.7% silicone surfactants), an anionic surfactant (25.5% alkylethersulfate sodium salt), and a vegetable oil (95% natural rapeseed oil with 5% compound emulsifiers) on the performance and rainfastness of a new commercial formulation of tribenuron‐methyl was assessed on four broad‐leaved weeds: wild mustard (Sinapis arvensis), scentless mayweed (Tripleurospermum inodorum), common poppy (Papaver rhoeas), and common lambsquarters (Chenopodium album). In one experiment, six doses of tribenuron‐methyl alone or in a mixture with each of the three adjuvants were applied to each weed species at two different leaf stages. In another experiment, the plants of T. inodorum were sprayed and subsequently subjected to 3 mm of rain at 1, 2, and 4 h after treatment (HAT). The activity of tribenuron‐methyl was significantly enhanced by all the adjuvants on all the weed species and only minor differences were observed among the tested adjuvants. The impact of the adjuvants varied among the weed species and growth stages. The highest response to the inclusion of adjuvants in the spray liquid was found at the late growth stage and on C. album, followed by P. rhoeas and T. inodorum, while S. arvensis was less responsive to the adjuvants. All the adjuvants significantly improved the rainfastness of tribenuron‐methyl on T. inodorum, with differences among the adjuvants being more pronounced when rain occurred shortly after herbicide application. The effect of the vegetable oil on tribenuron‐methyl's rainfastness was significantly lower than that of the surfactants with rain at 1 HAT, while no significant differences among the three adjuvants were observed when rain occurred at 2 and 4 HAT.     

Effects of reduced‐rate methyl bromide applications under conventional and virtually impermeable plastic film in perennial crop field nurseries

BACKGROUND: Producers of perennial crop nursery stock in California use preplant soil fumigation to meet state phytosanitary requirements. Although methyl bromide (MB) has been phased out in many agricultural industries, it is still the preferred treatment in the perennial nursery industry and is used under Critical Use Exemptions and Quarantine/Preshipment provisions of the Montreal Protocol. The present research was conducted to evaluate reduced‐rate MB applications sealed with conventional and low‐permeability plastic films compared with the primary alternative material. RESULTS: Reduced rates (100–260 kg ha^?1) of MB applied in combination with chloropicrin (Pic) and sealed with a low‐permeability plastic film provided weed and nematode control similar to the industry standard rate of 392 kg ha^?1 MB:Pic (98:2) sealed with high‐density polyethylene (HDPE) film. However, the primary alternative chemical, 1,3‐dichloropropene (1,3‐D), tended to provide slightly lower pest control even on sites with relatively low plant parasitic nematode, soil‐borne pathogen and weed pest pressure. CONCLUSION: If California regulations change to allow the use of low‐permeability films in broadcast fumigant applications, the results of this research suggest that reduced rates of MB in perennial crop nurseries could serve as a bridge strategy until more technically, economically and environmentally acceptable alternatives are developed. Published 2010 by John Wiley & Sons, Ltd.     

Surface water seal application to minimize volatilization loss of methyl isothiocyanate from soil columns

BACKGROUND: Metam‐sodium (MS, sodium methyldithiocarbamate) has been identified as a promising alternative chemical to replace methyl bromide (MeBr) in soil preplant fumigation. One degradation product of MS in soil is the volatile gas methyl isothiocyanate (MITC) which controls soilborne pests. Inconsistent results associated with MS usage indicate that there is a need to determine cultural practices that increase pest control efficacy. Sealing the soil surface with water after MS application may be a sound method to reduce volatilization loss of MITC from soils and increase the contact time necessary for MITC to control pests. The objective of this research was to develop a preliminary soil surface water application amount that would potentially inhibit the off‐gassing rate of MITC. RESULTS: Off‐gassing rate was consistently reduced with increasing water seal application. The application of a 2.5–3.8 cm water seal provided significantly lower (71–74% reduction in MITC volatilization) total fumigant loss compared with no water seal. The most favorable reduction in MITC off‐gassing was observed in the 2.5 cm water seal. CONCLUSION: This suggests that volatilization of MITC‐generating compounds can be highly suppressed using adequate surface irrigation following chemical application in this soil type (sandy clay loam), based on preliminary bench‐scale soil column studies. Copyright © 2010 Society of Chemical Industry     

四川盆地麦冬及其近缘植物的同工酶分析

采用聚丙烯酰胺凝胶电泳技术,作过氧化物(POD)同工酶、酯酶(EST)同工酶分析,并使用SPSS 17.0软件对谱带作相关及聚类分析,以探讨四川盆地不同产地25份麦冬及其近缘植物野生资源间的遗传多样性,为麦冬分类、鉴定和种质资源保护提供生化依据。结果显示,不同产地麦冬及其近缘植物样品的POD同工酶有10种酶谱类型,每种类型具有6~11条酶带;EST同工酶有15种酶谱类型,每种类型有4~8条酶带;同工酶系统聚类分析结果将25个样品被分为4类,并与染色体核型具有同一性。四川盆地麦冬种质资源,具有丰富的遗传多样性,POD、EST同工酶分析可以作为麦冬及其近缘植物种质资源鉴定的重要参考依据,并可将其加以区分,结合形态学、细胞学等经典理论研究,可判断其遗传差异及亲缘关系。