转5-烯醇式丙酮酰莽草酸-3-磷酸合酶(EPSPS)基因抗草甘膦烟草和棉花的获得

以从抗草甘膦的荧光假单胞菌(Pseudomonas fluorescens)G2中克隆的、并按双子叶植物偏爱密码子改造的5-烯醇式丙酮酰莽草酸-3-磷酸合酶(EPSPS)基因aroAG2M为目的基因,用菊花Rubisco小亚基的启动子驱动,在基因的5'端加叶绿体定位信号肽,构建植物表达载体。用根癌农杆菌(Agrobacterium tumefaciens)介导的叶盘法转化烟草(Nicotiana tabacum)获得转基因植株,PCR检测表明,外源基因已整合到烟草基因组中。转基因和非转基因植株6～8叶龄苗的叶片涂抹不同浓度的草甘膦异丙胺盐,表明转基因植株可抗4‰浓度的草甘膦,而非转基因对照植株则在2‰草甘膦时即死亡。花粉管通道法转化棉花(Gossypium hirsutum),得到3株具有草甘膦抗性的转基因植株,PCR和Southern检测显示,外源基因已整合到棉花基因组中,田间喷洒草甘膦异丙胺盐水剂,表明T1代转基因植株具有草甘膦抗性。     

Leafy启动子控制下5-烯醇式丙酮酰-莽草酸-3-磷酸合酶基因(CP4EPSPS)的表达增强芽对草甘膦的抗性

抗草甘膦基因在转基因植物体内持续高效表达,不但增加植物代谢压力,有的甚至改变植物形态造成植物的生长发育畸形。为了减少转基因植株的代谢负担和能源浪费,从拟南芥菜(Arabidopsis thaliana)基因组中克隆了Leafy组织特异性启动子替代CaMV35S启动子,用其驱动改造后加二磷酸核酮糖羧化酶(rubisco)小亚基引导肽的5-烯醇丙酮酰-莽草酸-3-磷酸合酶(CP4EPSPS)基因,同时调控报告基因gus的编码区构建植物表达载体p3300-Leafy-gus和p3300-Leafy-CP4EPSPS,嵌合基因经农杆菌(Agrobacterium)介导转化烟草。稳定表达后经GUS组织染色分析表明,Leafy驱动的gus表达仅局限在植物茎尖和幼叶部分,转基因植株成熟的叶片、茎部和根系均未能检测到GUS活性。草甘膦试验分析表明,Leafy驱动的CP4EPSPS的转基因植株幼芽部位有草甘膦抗性。结果表明,Leafy启动子驱动CP4EPSPS表达增强植株芽端对草甘膦的抗性。     

高粱5-烯醇式丙酮酰莽草酸-3-磷酸合酶基因(EPSPS)叶绿体转运肽(CTP)的克隆及其在转基因玉米中的功能验证

5-烯醇式丙酮酰莽草酸-3-磷酸合酶(EPSPS)催化莽草酸-3-磷酸(S3P)与磷酸烯醇式丙酮酸(PEP)合成5-烯醇式丙酮酰莽草酸-3-磷酸(EPSP),具有与草甘膦结合的活性位点,且结合后会抑制EPSPS的活性,在植物抗除草剂基因工程中具有重要的应用价值.为了培育抗草甘膦玉米(Zea mays),本研究通过对高粱(Sorghum bicolor)EPSPS基因的结构分析,克隆了该基因5'端的叶绿体转运肽(chloroplast transit peptide,CTP).将该转运肽与来源于农杆菌(Agrobacterium tumefaciens)菌株CP4 EPSPS基因整合,以Ubiquitin为启动子,35S polyA为终止子,构建表达载体,同时以不含有转运肽的CP4 EPSPS基因为对照,遗传转化玉米得到稳定转基因株系;用PCR、Southern blot、ELISA等方法检测转基因玉米CP4 EPSPS基因的表达量并对其进行草甘膦抗性检测,研究发现,不含转运肽的转化事件虽然CP4 EPSPS基因表达量与含有转运肽的基本一致但却不具有草甘膦抗性,而含有转运肽的转化事件则抗性明显.说明转运肽并不影响CP4 EPSPS基因的表达,但对转基因植株草甘膦抗性起着重要作用,说明本研究克隆的叶绿体转运肽能够正常行使其生物学功能.研究结果为利用EPSPS基因培育抗草甘膦作物提供了重要参考资料.     

印度梨形孢诱导烟草对黑胫病的抗性及其机理的初步研究

印度梨形孢(Piriformospora indica)是分离自印度塔尔沙漠的植物根系内生真菌,能够诱导多种植物对生物和非生物逆境产生抗性,目前已作为一种模式真菌用于内生真菌与植物互作关系的研究。为了研究印度梨形孢对烟草(Nicotiana tobacum)抗黑胫病的影响,本研究采用烟草疫霉菌(Phytophthora parasitica var.nicotianae)分别接种根部有印度梨形孢定殖与未定殖的烟草,观察接种后根部有印度梨形孢定殖与未定殖的烟草发病情况,测定抗病相关防御酶苯丙氨酸解氨酶(PAL)、过氧化物酶(POD)、多酚氧化酶(PPO)的活性变化及抗病相关基因的表达量,并通过平皿对峙试验研究印度梨形孢对烟草疫霉菌生长的影响。结果表明,接种烟草疫霉菌后,根部有印度梨形孢定殖的烟草发病严重度要显著低于对照;接种烟草疫霉菌后第1~10 d,根部有印度梨形孢定殖的烟草叶片中防御酶PAL、POD和PPO活性高于对照,在第1 d,PAL活性是对照烟草的3.99倍,在第2 d,POD活性是对照烟草的1.5倍,在第4 d,PPO活性是对照烟草的2.66倍;实时荧光定量PCR(Real-time quantitative PCR,q RT-PCR)结果显示,接种烟草疫霉菌后第6~96 h,根部有印度梨形孢定殖的烟草叶片中抗病相关基因PR1b、P450-2、hrs203J、Nm IMSP和P450-1的表达量高于对照;在第12 h,PR1b、P450-2、hrs203J的表达量分别是对照烟草的3.8、15.7和3.1倍,在第48 h,Nm IMSP的表达量是对照烟草的2.6倍,在第72 h,P450-1的表达量是对照烟草的1.5倍;平皿对峙试验结果显示印度梨形孢对烟草疫霉菌的生长没有抑制、重寄生作用。研究结果表明,印度梨形孢可显著提高烟草对黑胫病的抗性,对黑胫病的抗性不是通过印度梨形孢分泌的抗菌物质实现的,是与烟草中抗病相关基因表达量的上升、防御酶活性的提高有关。本研究初步揭示了印度梨形孢诱导烟草抗黑胫病的相关机理,为进一步深入研究烟草黑胫病的生物防治及其机理提供基础资料。     

氮胁迫对黄瓜幼苗抗氧化酶系统的影响

氮是植物所需的重要营养元素之一,氮缺乏会影响黄瓜的生长发育、营养品质及产量。该研究以黄瓜9930为材料,测定缺氮条件下黄瓜幼苗活性氧和丙二醛含量,抗氧化酶活性及基因表达量的变化。结果表明:缺氮处理6 h后黄瓜叶片内过氧化氢含量和超氧阴离子产生速率均显著上升,处理6 h时分别增长约100%和37%,丙二醛随着处理时间的延长不断累积,处理48 h时上调约25%,说明植物膜系统遭到破坏;植物抗氧化酶系统中的3种抗氧化酶(SOD、POD和CAT)的酶活性在缺氮的黄瓜叶片中均显著上升,处理48h分别上调约37%、24%和26%;这3种抗氧化酶的相关编码基因表达上调,其中SOD2、POD1和CATs上调幅度较大,SOD2上调约5倍,POD1和CATs上调约10倍。因此,该研究发现氮缺乏处理对黄瓜幼苗产生胁迫作用并诱导植株抗氧化酶系统响应,为了解黄瓜在氮胁迫下的抗逆机制提供有价值的线索。     

水稻白叶枯病菌蛋白质激发子HarpinXoo诱导植物的防卫反应

摘要：含质粒pHRF4的表达菌株BLHR4在培养基中经IPTG诱导，16 h Harpin表达接近最高量。用不同浓度的HarpinXoo喷雾处理烟草(Nicotiana tabacum L.)、油菜(Brassica campestris L.)和番茄(Lycopersicon esculentum Mill.)，对烟草花叶病毒(TMV)、油菜菌核病(Sclerotinia sclerotiorum (lib.) de Bary)和番茄灰霉病(Botrytis cinerea Pers.)均表现较好的诱导抗病效果。以浓度为100μg/mL的HarpinXoo处理烟草后，分别测定叶片中与防卫反应相关的一些生理指标的变化，结果表明，处理叶片中苯丙氨酸解氨酶（PAL）、过氧化物酶（PO）和多酚氧化酶（PPO）活性都有不同程度的增强。三种酶活性高峰分别在处理后24、12和3 h出现，分别比清水对照增加110.1%、211.2%和273.0%；同时，两个病程相关蛋白（pathogenesis-related protein，PR）基因PR-1b和PR-1a在HarpinXoo处理24 h后被诱导显著表达，36 h时达到最高表达水平。这表明HarpinXoo与HarpinEa一样能够诱导烟草不同抗病信号通路的启动，从而使植株获得抗病性。     

EMS不同处理浓度与时间对头花蓼的诱变效应初报

研究了不同诱变时间(12 h、24 h、36 h、48 h、72 h)和诱变浓度(0、0.2%、0.4%、0.6%、0.8%)下,化学诱变剂甲基磺酸乙酯(EMS)对头花蓼的诱变效应。结果表明,EMS诱变头花蓼种子的半致死剂量LD50为0.6%EMS处理24 h,0.8%EMS处理12 h。经过处理的头花蓼种子播种成苗后存在广泛变异,且变异类型丰富,主要表现为:叶片增大、叶片缩小、叶片变薄、叶面积增加、叶比重提高,此5项指标与对照相比差异达极显著;植株生长速度加快、花青素含量降低,此2项指标与对照相比差异显著;此外还有叶片皱缩、叶片表皮毛增加等类型。     

冀东野生大豆对草甘膦的耐性鉴定及耐性机制初步研究

为筛选耐草甘膦野生大豆种质并了解其耐性机制,本试验对采集于冀东地区的862份野生大豆进行了草甘膦的耐性鉴定。在草甘膦处理后,测定了高耐和敏感材料的莽草酸、丙二醛和叶绿素含量,过氧化物酶(POD)、过氧化氢酶(CAT)和超氧化物歧化酶(SOD)活性,以及草甘膦相关基因EPSPS表达量。结果显示,喷施草甘膦后,862份野生大豆材料中,药害等级在4级以上的材料占82.84%,3级占9.51%,2级占4.87%,1级占2.78%。筛选到高耐草甘膦的野生大豆材料Yong-33,其在1.125 kg a.i·hm^-2 草甘膦处理后植株存活率达到96.67%。经草甘膦处理后,与对照相比,高耐材料的叶绿素、丙二醛和莽草酸含量在检测的各时间点均无显著差异,敏感材料叶绿素含量显著降低,丙二醛和莽草酸含量显著升高;高耐材料POD、CAT和SOD活性以及EPSPS基因表达量均显著升高,而敏感材料酶活性及EPSPS基因表达量无显著差异。以上结果表明,野生大豆中存在高耐草甘膦的种质资源,在草甘膦处理后其植株内活性氧清除酶系活性升高,EPSPE基因上调表达,推测这是野生大豆对草甘膦耐性较好的原因。本研究筛选到的耐草甘膦野生大豆材料可为培育耐草甘膦栽培大豆新品种提供种质资源。     

外源抗坏血酸与谷胱甘肽对打顶后烟草氧化 还原平衡及烟碱的影响

烟碱含量偏高是我国烤烟的现状。如何有效降低烟叶烟碱含量,提高烤烟工业可用性是烟叶生产中的一个难题。根据烟草打顶导致烟碱含量急剧上升和机械损伤造成细胞氧化迸发的的现象,本试验从打顶创伤引起的一系列生理变化入手,采取打顶后在伤口涂抹抗氧化剂抗坏血酸+谷胱甘肽(As A+GSH)和抗坏血酸(As A)两种方法来抑制活性氧含量的上升,探究茉莉酸刺激烟碱含量上升和活性氧含量之间的关系,并比较两种方法在抑制活性氧及烟碱上升的效果。结果发现,涂抹As A+GSH和As A处理对烟草叶片超氧阴离子、过氧化氢、丙二醛的上升有抑制效果,过氧化氢降解速度慢于超氧阴离子,在烟草内有积累现象。涂抹As A+GSH和As A处理在打顶6 h时茉莉酸含量低于常规打顶,对茉莉酸的产生有抑制效果。其中处理96 h后,打顶后涂抹As A+GSH的处理叶片烟碱含量比常规打顶低21.5%,打顶后涂抹As A的处理叶片烟碱含量比常规打顶低17.5%。且各检测指标之间存在显著或极显著的相关性。另外,打顶后24 h,各处理的活性氧含量回到对照(不打顶)的水平。试验表明,抗氧化型物质(As A+GSH)涂抹打顶后烟草的伤口能有效抑制活性氧、茉莉酸和烟碱含量的上升,且活性氧、茉莉酸、烟碱之间存在着密切联系。As A+GSH比As A有更强的抗氧化性,能更好地抑制打顶后烟碱的上升。     

Foliar-applied glyphosate substantially reduced uptake and transport of iron and manganese in sunflower (Helianthus annuus L.) plants

Evidence clearly shows that cationic micronutrients in spray solutions reduce the herbicidal effectiveness of glyphosate for weed control due to the formation of metal-glyphosate complexes. The formation of these glyphosate-metal complexes in plant tissue may also impair micronutrient nutrition of nontarget plants when exposed to glyphosate drift or glyphosate residues in soil. In the present study, the effects of simulated glyphosate drift on plant growth and uptake, translocation, and accumulation (tissue concentration) of iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) were investigated in sunflower (Helianthus annuus L.) plants grown in nutrient solution under controlled environmental conditions. Glyphosate was sprayed on plant shoots at different rates between 1.25 and 6.0% of the recommended dosage (i.e., 0.39 and 1.89 mM glyphosate isopropylamine salt). Glyphosate applications significantly decreased root and shoot dry matter production and chlorophyll concentrations of young leaves and shoot tips. The basal parts of the youngest leaves and shoot tips were severely chlorotic. These effects became apparent within 48 h after the glyphosate spray. Glyphosate also caused substantial decreases in leaf concentration of Fe and Mn while the concentration of Zn and Cu was less affected. In short-term uptake experiments with radiolabeled Fe (59Fe), Mn (54Mn), and Zn (65Zn), root uptake of 59Fe and 54Mn was significantly reduced in 12 and 24 h after application of 6% of the recommended dosage of glyphosate, respectively. Glyphosate resulted in almost complete inhibition of root-to-shoot translocation of 59Fe within 12 h and 54Mn within 24 h after application. These results suggest that glyphosate residues or drift may result in severe impairments in Fe and Mn nutrition of nontarget plants, possibly due to the formation of poorly soluble glyphosate-metal complexes in plant tissues and/or rhizosphere interactions.     

Low Concentrations of Glyphosate-Based Herbicide Affects the Development of <Emphasis Type="Italic">Chironomus xanthus</Emphasis>

Glyphosate is an herbicide commonly used worldwide for weed control and generally applied as part of a formulated product, such as Roundup. Contamination of surface water by glyphosate-based herbicides can cause deleterious effects in organisms, mainly in aquatic systems near to intensive agricultural areas (e.g., transgenic soybean crops). Given the lack of toxicological information concerning effects of glyphosate-based herbicides on tropical aquatic ecosystems, we aimed to evaluate the lethal and sub-lethal effects of Roundup Original® on the dipteran Chironomus xanthus. The endpoints evaluated included survival, growth, and emergence. The results showed that the 48 h LC₅₀ for glyphosate to C. xanthus was 251.5 mg a.e./L. Larval growth of C. xanthus was reduced under glyphosate exposure (LOEC for body length = 12.06 mg/L; LOEC for head capsule width = 0.49 mg/L). No effects were observed in terms of cumulative percentage of imagoes emergence. However, low concentrations of glyphosate caused delayed emergence of females (at 1.53 mg/L) and induced fast emergence of males (at 0.49 mg/L), compared to control treatment. The deleterious effects of environmental relevant concentrations of glyphosate (0.7 mg/L) observed in terms of C. xanthus growth and development suggest that glyphosate-based herbicides can have negative consequences for aquatic non-target invertebrates such as Chironomus. Multigerational assays are needed to assess the long term effects of glyphosate on C. xanthus populations. Finally, our study adds ecotoxicological data on the effects of glyphosate-based herbicides on tropical freshwater invertebrates.     

Effects of Glyphosate on Somatic and Ovarian Growth in the Estuarine Crab <Emphasis Type="Italic">Neohelice granulata</Emphasis>, During the Pre-Reproductive Period

Adult females of the estuarine crab Neohelice granulata were exposed during the 3-month pre-reproductive period (winter) to the herbicide glyphosate, the most used pesticide in Argentina, at three different concentrations (0.02, 0.2, and 1 mg/L, as active ingredient). At the end of the in vivo assay, the body weight gain and the ovarian growth were estimated, the last one in terms of the gonadosomatic index (GSI), the relative proportion of the different kind of oocytes, and their relative size. A decrease in the body weight gain was observed by effect of pure glyphosate, at all concentrations assayed. Although no differences in either the GSI or vitellogenic protein content of the ovary were noted between any glyphosate concentration and control, a higher proportion of reabsorbed vitellogenic oocytes was observed in the ovaries of crabs exposed to glyphosate at 1 mg/L, together with an increased area of previtellogenic oocytes. These effects were confirmed in vitro, at a glyphosate concentration of 0.2 mg/L. In fact, a higher area of previtellogenic oocytes was seen when glyphosate was added to the culture medium containing ovarian tissue, but a significant higher incidence of reabsorbed vitellogenic oocytes was seen only when eyestalk tissue was also added to the vials, suggesting that the secretion of some neurohormone involved in reabsorption is enhanced. The obtained results indicate that glyphosate is able to harm, in the studied species, both somatic and the ovarian growth.     

缺磷胁迫下草甘膦对抗草甘膦大豆幼苗光合作用和叶绿素荧光参数的影响1

为探明缺磷胁迫下草甘膦对抗草甘膦大豆（RR1）幼苗叶片光合作用和叶绿素荧光参数的影响,采用溶液培养方法,在大豆长出真叶时进行缺磷胁迫,第二复叶完全展开时进行草甘膦处理,5d后测定各生理指标。结果表明, 相对于正常供磷条件的清水处理,缺磷胁迫下4.98 mL/L草甘膦处理的大豆叶片净光合速率（Pn）、气孔导度（Gs）、胞间CO2浓度（Ci）、最大荧光（Fm）、PSⅡ最大光化学效率（Fv/Fm）、PSⅡ的有效量子产量［Y(Ⅱ)］、PSⅡ非调节性能量耗散的量子产量［Y(NO)］、最大电子传递速率（ETRmax）和半饱和光强（Ik）均呈下降趋势。而气孔限制值（Ls）、叶绿素a（Chl a）、叶绿素b（Chl b）、叶绿素a/b（Chl a/b）、类胡萝卜素（Car）、总叶绿素（Chl）含量和PSⅡ调节性能量耗散的量子产量［Y(NPQ)］均呈升高趋势。说明缺磷胁迫条件下喷施草甘膦显著降低了抗草甘膦大豆的光合速率。缺磷引起的气孔因素可能是导致RR大豆光合速率下降的主要原因,而光合速率的下降导致其PSⅡ反应中心的开放程度降低,活性减弱,参与CO2固定的电子较少,光化学效率较低。     

Impact of glyphosate application on microbial biomass and metabolic activity in a Vertic Argiudoll from Argentina

The widespread use of genetically modified crops tolerant to glyphosate, has strongly promoted the use of this herbicide. This work evaluates the effect of increasing doses of glyphosate on biomass and metabolic activity and metabolic quotient of soil microbiota under controlled conditions. Commercial formulation of glyphosate (48%) was sprayed over a Vertic Argiudoll placed in trays, at doses of 0.48, 0.96, 1.92 and 3.84 L a.i ha^?1. Doses usually applied in the field are between 0.96 and 1.92 L a.i ha^?1. Treatments and control were incubated at 25 °C and 75% of water holding capacity. After 4 and 45 days from glyphosate application, carbon from microbial biomass (C-MB), microbial respiration rate (MR), metabolic quotient (qCO₂), and dehydrogenase activity (DA) were determined. The C-MB at 4 days of incubation did not differ (P < 0.05) between the control and the doses of 0.48 and 0.96 L, while it was significantly lower in the highest doses. After 45 days, C-BM in the dose of 3.84 L was significantly lower than the control. The MR showed significant differences over the time but not between doses. Significant differences were found in qCO₂ between doses in both periods of incubation. Dehydrogenase activity was significantly higher in the treatments with glyphosate than in the control at the beginning of incubation. Treatment with 0.48 L presented the highest value after 45 days, while the dose of 3.84 L had lowest DA. The variables analyzed showed an initial inhibitory effect that affected the microbial cells. However, this effect was temporary at doses equivalent or higher than those usually applied in the field.     

Aminomethylphosphonic acid accumulation in plant species treated with glyphosate

Aminomethylphosphonic acid (AMPA) is the most frequently detected metabolite of glyphosate in plants. The objective of this study was to determine if there is any correlation of metabolism of glyphosate to AMPA in different plant species and their natural level of resistance to glyphosate. Greenhouse studies were conducted to determine the glyphosate I 50 values (rate required to cause a 50% reduction in plant growth) and to quantify AMPA and shikimate concentrations in selected leguminous and nonleguminous species treated with glyphosate at respective I 50 rates. Coffee senna [ Cassia occidentalis (L.) Link] was the most sensitive ( I 50 = 75 g/ha) and hemp sesbania [ Sesbania herbacea (P.Mill.) McVaugh] was the most resistant ( I 50 = 456 g/ha) to glyphosate. Hemp sesbania was 6-fold and Illinois bundleflower [ Desmanthus illinoensis (Michx.) MacM. ex B.L.Robins. & Fern.] was 4-fold more resistant to glyphosate than coffee senna. Glyphosate was present in all plant species, and its concentration ranged from 0.308 to 38.7 microg/g of tissue. AMPA was present in all leguminous species studied except hemp sesbania. AMPA concentration ranged from 0.119 to 4.77 microg/g of tissue. Shikimate was present in all plant species treated with glyphosate, and levels ranged from 0.053 to 16.5 mg/g of tissue. Non-glyphosate-resistant (non-GR) soybean accumulated much higher shikimate than glyphosate-resistant (GR) soybean. Although some leguminous species were found to be more resistant to glyphosate than others, and there was considerable variation between species in the glyphosate to AMPA levels found, metabolism of glyphosate to AMPA did not appear to be a common factor in explaining natural resistance levels.     

Simulated glyphosate drift influences nitrate assimilation and nitrogen fixation in non-glyphosate-resistant soybean

Nontarget injury from glyphosate drift is a concern among growers using non-glyphosate-resistant (non-GR) cultivars. The effects of glyphosate drift on nitrate assimilation and nitrogen fixation potential, nodule mass, and yield of non-GR soybean were assessed in a field trial at Stoneville, MS. A non-GR soybean cultivar 'Delta Pine 4748S' was treated with glyphosate at 12.5% of use rate of 0.84 kg of active ingredient/ha at 3 (V2), 6 (V7), and 8 (R2, full bloom) weeks after planting (WAP) soybean to simulate glyphosate drift. Untreated soybean was used as a control. Soybeans were sampled weekly for 2 weeks after each glyphosate treatment to assess nitrate assimilation and N2 fixation potential. Nitrate assimilation was assessed using in vivo nitrate reductase assay in leaves, stems, roots, and nodules. Nitrogen fixation potential was assessed by measuring nitrogenase activity using the acetylene reduction assay (ARA). Nitrogen content of leaves, shoots, and seed and soybean yield were also determined. In the first sampling date (4 WAP), glyphosate drift caused a significant decrease in NRA in leaves (60%), stems (77%), and nodules (50%), with no decrease in roots. At later growth stages, NRA in leaves was more sensitive to glyphosate drift than stems and roots. Nitrogenase activity was reduced 36-58% by glyphosate treatment at 3 or 6 WAP. However, glyphosate treatment at 8 WAP had no effect on nitrogenase activity. Nitrogen content was affected by glyphosate application only in shoots after the first application. No yield, seed nitrogen, protein, or oil concentration differences were detected. These results suggest that nitrate assimilation and nitrogen fixation potential were significantly reduced by glyphosate drift, with the greatest sensitivity early in vegetative growth. Soybean has the ability to recover from the physiological stress caused by glyphosate drift.     

Glyphosate-resistant and -susceptible soybean (Glycine max) and canola (Brassica napus) dose response and metabolism relationships with glyphosate

Experiments were conducted to determine (1) dose response of glyphosate-resistant (GR) and -susceptible (non-GR) soybean [Glycine max (L.) Merr.] and canola (Brassica napus L.) to glyphosate, (2) if differential metabolism of glyphosate to aminomethyl phosphonic acid (AMPA) is the underlying mechanism for differential resistance to glyphosate among GR soybean varieties, and (3) the extent of metabolism of glyphosate to AMPA in GR canola and to correlate metabolism to injury from AMPA. GR50 (glyphosate dose required to cause a 50% reduction in plant dry weight) values for GR (Asgrow 4603RR) and non-GR (HBKC 5025) soybean were 22.8 kg ae ha-1 and 0.47 kg ha-1, respectively, with GR soybean exhibiting a 49-fold level of resistance to glyphosate as compared to non-GR soybean. Differential reduction in chlorophyll by glyphosate was observed between GR soybean varieties, but there were no differences in shoot fresh weight reduction. No significant differences were found between GR varieties in metabolism of glyphosate to AMPA, and in shikimate levels. These results indicate that GR soybean varieties were able to outgrow the initial injury from glyphosate, which was previously caused at least in part by AMPA. GR50 values for GR (Hyola 514RR) and non-GR (Hyola 440) canola were 14.1 and 0.30 kg ha-1, respectively, with GR canola exhibiting a 47-fold level of resistance to glyphosate when compared to non-GR canola. Glyphosate did not cause reduction in chlorophyll content and shoot fresh weight in GR canola, unlike GR soybean. Less glyphosate (per unit leaf weight) was recovered in glyphosate-treated GR canola as compared to glyphosate-treated GR soybean. External application of AMPA caused similar injury in both GR and non-GR canola. The presence of a bacterial glyphosate oxidoreductase gene in GR canola contributes to breakdown of glyphosate to AMPA. However, the AMPA from glyphosate breakdown could have been metabolized to nonphytotoxic metabolites before causing injury to GR canola. Injury in GR and non-GR canola from exogenous application of AMPA was similar.     

应用~(14)C核素研究草甘膦在水域生态系中的迁移、生物富集与消失动态

采用室内模拟与室外试验相结合的方法 ,研究了除草剂草甘膦在水域生态系统中的环境行为、生物富集作用和消失动态。表明该药进入水系后迅速向水生植物(金鱼藻CeratopyllumdemersumL .)和底泥中发生迁移 ;5～ 1 0d后以更快的速率向水生动物 (麦穗鱼Psudorasoboraparva)体内迁移并积累。 2 0d时的分配系数和生物富集系数分别达 8 59、2 7 96和 45 79,系统中草甘膦的浓度分布为麦穗鱼 >金鱼藻 >沉积物 >水体。鱼塘和河道用药后 ,草甘膦在水和沉积物之间的迁移及消失则更为迅速。     

狗蔷薇RaWUS基因组成型表达对烟草叶片形态的影响

为验证从狗蔷薇类原球茎克隆的RaWUS基因的功能,构建了组成型表达载体,并用根瘤农杆菌介导的叶盘转化法对烟草进行了遗传转化。通过除草剂草丁膦筛选,获得了转基因植株并对其进行了表型观察和RT．PCR分析。结果显示转基因烟草叶片形态和叶脉表现出形态变化,包括叶片浅裂、叶片边缘波浪状、叶脉紊乱,甚至叶片的主脉上有不定芽的产生等。RT-PCR分析表明,RaWUS基因仅仅在经过草丁膦筛选的抗性转基因烟草中强烈表达,在野生型烟草中没有表达。表明RaWUS基因已经被成功转入烟草中,并可能通过改变激素的水平和调控维管束的发育来影响叶片形状。