草甘膦在抗除草剂油菜田的应用研究初报

油菜是杂草危害较为严重的作物之一,我国冬油菜区草害面积达45%～48%,中度以上危害的面积达22%～23%,春油菜区危害面积高达80%以上,草害已成为制约我国油菜生产水平提高的重要因素.目前,防治油菜田单子叶类杂草如禾本科杂草,使用稳杀得、盖草能、禾草克等除草剂就能收到较好的防治效果,但对双子叶类的阔叶杂草还没有理想的除草剂.     

Simulating evolution of glyphosate resistance in Lolium rigidum II: past, present and future glyphosate use in Australian cropping

Glyphosate is a key component of weed control strategies in Australia and worldwide. Despite widespread and frequent use, evolved resistance to glyphosate is rare. A herbicide resistance model, parameterized for Lolium rigidum has been used to perform a number of simulations to compare predicted rates of evolution of glyphosate resistance under past, present and projected future use strategies. In a 30‐year wheat, lupin, wheat, oilseed rape crop rotation with minimum tillage (100% shallow depth soil disturbance at sowing) and annual use of glyphosate pre‐sowing, L. rigidum control was sustainable with no predicted glyphosate resistance. When the crop establishment system was changed to annual no‐tillage (15% soil disturbance at sowing), glyphosate resistance was predicted in 90% of populations, with resistance becoming apparent after between 10 and 18 years when sowing was delayed. Resistance was predicted in 20% of populations after 25–30 years with early sowing. Risks of glyphosate resistance could be reduced by rotating between no‐tillage and minimum‐tillage establishment systems, or by rotating between glyphosate and paraquat for pre‐sowing weed control. The double knockdown strategy (sequential full rate applications of glyphosate and paraquat) reduced risks of glyphosate and paraquat resistance to <2%. Introduction of glyphosate‐resistant oilseed rape significantly increased predicted risks of glyphosate resistance in no‐tillage systems even when the double knockdown was practised. These increased risks could be offset by high crop sowing rates and weed seed collection at harvest. When no selective herbicides were available in wheat crops, the introduction of glyphosate‐resistant oilseed rape necessitated a return to a minimum‐tillage crop establishment system.     

A risk calculator for glyphosate resistance in Lolium rigidum (Gaud.)

BACKGROUND: Glyphosate resistance has been confirmed in 58 populations of Lolium rigidum (Gaud.), a major weed of crops in southern Australia. Extensive use of glyphosate in conjunction with minimal soil disturbance has been identified as high risk for resistance to that herbicide. Land managers need a simple method for rapid assessment of the risk of resistance occurring as a result of past and proposed future management practices. Modelled on risk assessment nomographs, a simple calculator for indicating the risk of evolved glyphosate resistance in L. rigidum is described. RESULTS: The calculator uses the generations since first use and the frequency of use of glyphosate in combination with historical cultivation levels as critical factors for determining the risk of glyphosate resistance evolution. Based on the management history of a field, a land manager can graphically determine a glyphosate resistance risk for that field. CONCLUSION: The calculator enables the farmer or the advisor to assess the risk of a weed's population becoming resistant and modify practices accordingly to manage for sustainable glyphosate use. The risk calculator could be modified for other herbicides and different weed species.     

草甘膦作用机制和抗性研究进展

草甘膦是迄今为止最为重要、应用最广泛和最优秀的除草剂之一。然而,由于抗草甘膦转基因作物的广泛商业化导致草甘膦使用量迅速增长,杂草抗药性发生,这不仅对草甘膦的药效发挥和未来可持续应用造成了严重影响,而且对现代农业生产安全构成了威胁。本文通过对草甘膦的作用机理、草甘膦抗性杂草发展现状和抗性机制进行系统的总结和分析,以期为我国草甘膦的抗性研究和科学使用提供参考。     

抗草甘膦杂草及其检测方法发展现状

草甘膦在世界范围的多年大量使用已经引起了抗草甘膦杂草的产生。本文针对全球迄今为止发现的21种抗草甘膦杂草的发生、发展状况进行了论述。探讨了抗草甘膦杂草抗药性检测方法,分别从整株生物测定及生物化学等方面介绍了抗草甘膦杂草检测方法的研究现状,为抗草甘膦杂草检测方法的发展及其抗性监测方法的建立提供参考。     

棉铃疫病菌对甲霜灵的抗药性风险研究

在实验室条件下,对分离自安徽省芜湖、无为、宣城、望江、肥东、寿县、滁州等7个地区的棉铃疫病菌(Phytophthora boehmeriae Sawada)对甲霜灵的抗药性进行了测定。结果显示,甲霜灵对各供试菌株的EC50分布为0.008 3～0.079 1μg／mL,平均为0.026 1 μg／mL,远小于1 μg／mL,且供试菌株在含甲霜灵质量浓度为1μg／mL的LBA平板上菌丝生长几乎完全被抑制,表明各供试菌株对甲霜灵十分敏感,但其敏感程度地区间存在较大差异。通过室内药剂直接诱变,获得抗甲霜灵菌株,经抗性测定结果表明,抗性菌株的抗性水平较其敏感亲本菌株高13 000倍以上,提示安徽省棉铃疫病菌对甲霜灵具有潜在的抗药性风险。     

Conyza sumatrensis: A new weed species resistant to glyphosate in the Americas

Recent reports of weed‐control failures after the use of glyphosate led to suspicion about the selection of resistant biotypes of Conyza at locations in west and north Paraná, Brazil. Plants were collected, identified as Conyza sumatrensis and subsequently evaluated for possible resistance to glyphosate in four stages of weed development. The experiments were carried out in a greenhouse by combining biotypes, stages of development and a range of glyphosate doses. All the suspected biotypes were collected from locations in Cascavel, Toledo, Assis Chateaubriand, Tupãssi and Campo Mourão with a history of glyphosate use in burndown and in glyphosate‐resistant soybean for at least the four previous years and were compared to a susceptible biotype (São Jorge do Ivaí) with no previous history of herbicide use. The doses of glyphosate ranged from 0 to 5760 g ae ha^?1. The biotypes were considered as resistant if two combined criteria were present (resistance factor > 1 and the rate required to achieve 80% control is >720 g ha^?1). The results provided evidence that there is a marked difference in the level of control of older plants and also confirmed the presence of some resistant biotypes. For applications at the first stage of development, two biotypes that were resistant to glyphosate were identified (Cascavel‐1 and Tupãssi‐6). For applications in the second stage of development, beyond the biotypes that were found in the first stage, three other biotypes were considered as resistant: Toledo‐5, Assis Chateaubriand‐7 and Floresta‐10. However, for applications at the third and fourth stages, all the biotypes were considered as resistant.     

Characterization of glyphosate resistance in cloned Amaranthus palmeri plants

Glyphosate‐resistant Palmer amaranth from Georgia (GA), USA, possesses multiple copies of the gene that encodes 5‐enolpyruvylshikimate‐3‐phosphate synthase (EPSPS), the enzyme target site of this herbicide. The cloned plants of glyphosate‐resistant and glyphosate‐susceptible Palmer amaranth biotypes from Mississippi (MS), USA, and GA were evaluated for glyphosate injury (digital imaging) in leaf disc bioassays. Four groups (three resistant groups: two from MS [G and R] and one from GA [C7]; one susceptible group from GA [C3]) were chosen for cloning to facilitate long‐term studies. After exposure to glyphosate (1.0 mmol L^–1, 144 h), the level of injury (mean value) was low in the resistant groups, while a higher level of injury was found in the susceptible group. However, the individual injury values within all groups varied widely. The mean EPSPS gene copy number of these groups was G ≥ R > C7 >>> C3. However, a higher copy number did not always convey increased resistance in these bioassays. When the copy number was high (>20), 81.5% of the bioassayed plants exhibited little or no injury and only ～20% were significantly injured, while 50% of the plants with a low copy number (<20) remained healthy. Overall, no strong statistical correlation of the copy number versus injury occurred in these cloned plants and no statistical relationship of resistance and copy number with the sex of the MS plants was observed. The results suggest that although an elevated copy number of the EPSPS gene can instill resistance, other mechanisms might contribute to the overall glyphosate resistance of Palmer amaranth in these plants.     

Rapid vacuolar sequestration: the horseweed glyphosate resistance mechanism

BACKGROUND: Glyphosate‐resistant (GR) weed species are now found with increasing frequency and threaten the critically important GR weed management system. RESULTS: The reported ³¹P NMR experiments on glyphosate‐sensitive (S) and glyphosate‐resistant (R) horseweed, Conyza canadensis (L.) Cronq., show significantly more accumulation of glyphosate within the R biotype vacuole. CONCLUSIONS: Selective sequestration of glyphosate into the vacuole confers the observed horseweed resistance to glyphosate. This observation represents the first clear evidence for the glyphosate resistance mechanism in C. canadensis. Copyright © 2010 Society of Chemical Industry     

Sustainable use of glyphosate in North American cropping systems

Roundup Ready (glyphosate-resistant) cropping systems enable the use of glyphosate, a non-selective herbicide that offers growers several benefits, including superior weed control, flexibility in weed control timing and economic advantages. The rapid adoption of such crops in North America has resulted in greater glyphosate use and concern over the potential for weed resistance to erode the sustainability of its efficacy. Computer modeling is one method that can be used to explore the sustainability of glyphosate when used in glyphosate-resistant cropping systems. Field tests should help strengthen the assumptions on which the models are based, and have been initiated for this purpose. Empirical evaluations of published data show that glyphosate-resistant weeds have an appearance rate of 0.007, defined as the number of newly resistant species per million acres treated, which ranks low among herbicides used in North America. Modeling calculations and ongoing field tests support a practical recommendation for growers occasionally to include other herbicides in glyphosate-resistant cropping systems, to lower further the potential for new resistance to occur. The presented data suggest that the sustainability of glyphosate in North America would be enhanced by prudent use of additional herbicides in glyphosate-resistant cropping systems.     

新疆棉花主产区土地流入对棉花生产的影响

科学测定土地流入对棉花生产的影响,识别棉花适度经营规模范围,对推进土地流转和确保棉花产业安全具有重要意义.文中基于新疆棉花主产区591份棉花种植户的微观数据,利用倾向值匹配法测算了土地流入对棉花生产的影响.结果表明:考虑样本农户自选择和内生性问题后,土地流入使籽棉亩产量平均提升29.20kg;在现有的技术水平下,棉花种...     

Physiological and molecular mechanisms of glyphosate tolerance in an in vitro selected cotton mutant

We have selected an upland cotton (Gossypium hirsutum L.) cell line (R1098) that is highly tolerant to glyphosate. This cell line was developed by in vitro selection with gradually increasing glyphosate concentrations, and its mechanisms conferring glyphosate tolerance were studied. Based on a whole-plant dose–response bioassay, R1098 plants were tolerant to glyphosate at a concentration of 1500 g ae ha⁻¹ glyphosate (1.5× the recommended field rate) whereas the control plants (Coker 312) were unable to survive at 150 g ae ha⁻¹ glyphosate. Coker 312 accumulated 13.1 times more shikimate in leaves at 5 days after glyphosate treatment (1500 g ae ha⁻¹) than that of R1098. Two distinct cDNAs for 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), EPSPS-1 and EPSPS-2, were isolated from R1098. Both cDNAs were 97.7% identical within the common protein-coding region and the predicted sequences of the mature proteins were greater than 83% identical with EPSPS proteins from other known higher plants. In comparison to the glyphosate-susceptible cotton Coker 312, sequence analysis of the EPSPS-1 gene indicated that R1098 has an alanine insertion at nucleotide position 1216 resulting in frameshift. It leads to two copy functional EPSPS genes in R1098. There was no difference between R1098 and Coker 312 in EPSPS mRNA levels before glyphosate treatment. However, its treatment caused a 2–4 times increase in the basal EPSPS mRNA level in R1098.     

Managing the risk of insect resistance to transgenic insect control traits: practical approaches in local environments

BACKGROUND: Growers have enthusiastically embraced crops genetically modified to express Bacillus thuringiensis (Bt) proteins for insect control because they provide excellent protection from key damaging insect pests around the world. Bt crops also offer superior environmental and health benefits while increasing grower income. However, insect resistance development is an important concern for all stakeholders, including growers, technology providers and seed companies that develop these genetically modified crops. Given the marked benefits associated with Bt crops, insect resistance management (IRM) must be a consideration when cultivating these crops. RESULTS: The technical data and practical experience accumulated with Bt crops in many global regions can inform different aspects of resistance management leading to robust, science‐based IRM plans. A range of elements should be considered in assembling any IRM strategy, including: pest biology/ecology, product deployment patterns, local cropping systems, insect susceptibility monitoring, stakeholder/grower communications, and a remedial action plan should resistance develop. Each of these elements is described in more detail, with specific examples of how these elements can be combined and tailored to the local/regional environments and grower practices. CONCLUSION: IRM plans need to be suitable for the given production situation. What works for large monoculture production systems in North America is unlikely to be appropriate for the small, more diverse agriculture of southeast Asia or Africa. Though it is clear that Bt crops impart considerable value to growers, it is also clear that it is in the best interest of all stakeholders to preserve Bt proteins for the long‐term benefits they provide. Copyright © 2009 Society of Chemical Industry     

不同生育期转基因抗草甘膦抗虫棉花对草甘膦的耐受性

为明确转基因抗草甘膦抗虫棉田草甘膦的使用适期,于棉花子叶期、3~4片真叶期和花铃期喷施不同浓度的草甘膦,比较药害发生情况、棉花产量和纤维品质。棉花子叶期、3~4片真叶期和花铃期喷施1 640~9 840 g/hm²(有效成分,下同)草甘膦后,施药初期棉花均表现出一定的药害症状,药后4~8 d药害株率和药害指数达最大值,药后12 d药害症状逐渐减轻或消失。棉花子叶期和3~4片真叶期喷施草甘膦,对棉花产量无显著影响,但棉花花铃期喷施2 460~9 840 g/hm²草甘膦后,棉花产量显著降低,降幅达35.0%~63.3%。3个时期喷施草甘膦均不影响棉花的纤维品质。研究表明,转基因抗草甘膦抗虫棉田草甘膦的使用适期为棉花苗期。