Crops In Argentina Research Articles

First Report of Bothynus striatellus (Coleoptera: Melolonthidae) Damaging Lucerne Crops in Argentina.

We report for the first time that larvae of the genus Bothynus Hope (Coleoptera: Melolonthidae) caused economic damage to lucerne (Medicago sativa L., Fabaceae) crops in General Acha, province of La Pampa, Argentina. In two consecutive years (2021 and 2022), this insect infested 150ha of lucerne, causing seedling losses of 80ha. Based on soil sampling and laboratory insect rearing, the species was identified as Bothynus striatellus (Faimaire) (Coleoptera: Melolonthidae). Information is given here on the damage recorded in this forage crop, the density of the larvae observed at the time of damage assessment and the morphological characteristics of the third instar larvae reported in this crop in Argentina.

Herbicide‐resistant weeds from dryland agriculture in Argentina

AbstractWe reviewed and performed a quantitative synthesis on herbicide‐resistant weeds from rain‐fed crops in Argentina. Twenty‐four weed species distributed in the main extensive crops (soybean, maize, wheat, barley, oilseed rape, sunflower, chickpea and peanut) have evolved herbicide resistance. Of the total, 54% are grasses, 88% are annual species and 63% are cross‐pollinated species. The most representative families were Poaceae with 54% resistant species, followed by Brassicaceae with 17%, and Asteraceae with 13%. Buenos Aires, Santa Fe and Córdoba were the provinces with the most documented cases of resistance (35%, 33% and 30%, respectively). The proportion of cases resistant to pre‐emergence herbicides was 10%, whereas the proportion of cases resistant to post‐emergence herbicides was 90%. Glyphosate was the herbicide with the highest incidence (92%) of resistance among weed species, followed by 29% of species that evolved resistance to ALS‐inhibiting herbicides. Whereas resistance to auxin‐like herbicides comprised 17% of the weed species, acetyl‐CoA carboxylase (8%) and protoporphyrinogen oxidase (4%) inhibiting herbicides showed the least incidence of resistance evolution among weeds. The highest number of resistant species was identified in soybean (19), followed by maize (13), wheat/barley (10) and fallow (9). Weed species with a higher number of resistant populations to a higher number of herbicide mode of action were Amaranthus hybridus, A. palmeri, Lolium multiflorum and Raphanus sativus. The change in the production system since the mid‐1990s, based on the use of herbicides (glyphosate mainly) to control weeds, is likely to account for the notorious increase in the average rate of evolution of herbicide‐resistant weeds in Argentina.

Aflatoxin Decontamination in Maize Steep Liquor Obtained from Bioethanol Production Using Laccases from Species within the Basidiomycota Phylum.

Maize (Zea mays L.) is an important crop in Argentina. Aspergillus section Flavi can infect this crop at the pre-harvest stage, and the harvested grains can be contaminated with aflatoxins (AFs). During the production of bioethanol from maize, AF levels can increase up to three times in the final co-products, known as, dry and wet distiller's grain with solubles (DDGS and WDGS), intended for animal feed. Fungal enzymes like laccases can be a useful tool for reducing AF contamination in the co-products obtained from this process. The aim of the present study was to evaluate the ability of laccase enzymes included in enzymatic extracts (EE) produced by different species in the Basidiomycota phylum to reduce AF (AFB1 and AFB2) accumulation under the conditions of in vitro assays. Four laccase activities (5, 10, 15, and 20 U/mL) exerted by nine isolates were evaluated in the absence and presence of vanillic acid (VA), serving as a laccase redox mediator for the degradation of total AFs. The enzymatic stability in maize steep liquor (MSL) was confirmed after a 60 h incubation period. The most effective EE in terms of reducing AF content in the buffer was selected for an additional assay carried out under the same conditions using maize steep liquor obtained after the saccharification stage during the bioethanol production process. The highest degradation percentages were observed at 20 U/mL of laccase enzymatic activity and 1 mM of VA, corresponding to 26% for AFB1 and 26.6% for AFB2. The present study provides valuable data for the development of an efficient tool based on fungal laccases for preventing AF accumulation in the co-products of bioethanol produced from maize used for animal feed.

Population genetic diversity in Nezara viridula by analysis of mitochondrial control region sequences

Abstract Here, we examine genetic diversity and dispersal patterns in populations of the agricultural pest Nezara viridula from Argentina using mitochondrial control region sequences. The DNA sequence comparisons of 1837 base pairs of the control region revealed 60 haplotypes determined by a total of 108 variable sites. The observed total haplotype diversity (Hd) value was 0.99, and the nucleotide diversity was 0.00423 and 0.00571 according to π and θW, respectively. The high haplotype diversity and low nucleotide diversity, as well as both neutrality tests and unimodal mismatch distributions, suggested a recent expansion in the populations of N. viridula from Argentina. The expansion of the populations of this insect is probably due to the recent agricultural expansion and intensification of soybean cultivation in this country. No significant levels of genetic differentiation were detected, suggesting that gene flow predominates over genetic drift. In addition, the Bayesian individual assignment analysis revealed that all populations share ancestry. It is probable that the growth in the area cultivated with soybean has generated stable and continuous habitats that allow gene flow among populations of N. viridula. The results of demographic history analysis suggest that the direction of migration of N. viridula would be associated with the growth pattern of soybean crops in Argentina.

Environmental potential for crop production and tenure regime influence fertilizer application and soil nutrient mining in soybean and maize crops

CONTEXTDifferences in land tenure regimes are one challenge to implementing soil conservation practices in agricultural systems. It is frequently assumed that tenants are less likely to adopt soil conservation strategies than owners, given a shorter-term engagement with the field. Also, the field's environmental potential (i.e., potential for agricultural production) may influence farmers' investment decisions, since high-potential fields increase the chances of achieving a return on the investment. OBJECTIVEUnderstand the effect of land tenure regimes and environmental potential on fertilization rates and balance of nitrogen, phosphorus, and sulfur in soybean and maize crops in Argentina. METHODSWe applied mixed-effects models on a database of 52,588 fields of soybean and maize farms, covering a total area of 3.8 M ha in Argentina during the period of 2017–2022. RESULTS AND CONCLUSIONSOverall, the balance of nitrogen, phosphorus, and sulfur was (mean ± SE) −29.11 ± 0.15, −2.58 ± 0.38, and 8.26 ± 0.044 kg ha−1 yr−1, respectively. Despite 8.04 and 0.63 kg ha−1 yr−1 more nitrogen and phosphorus were applied in high-potential compared to low-potential maize fields, nutrient outputs were still higher. Therefore, net nutrient exports of the most productive fields increased by 9.99 and 2.06 kg ha−1 yr−1 for nitrogen and phosphorus, respectively. In soybean fields, environmental potential had no effect on nutrient application, but the net export of nitrogen and phosphorus was 9.85 and 2.14 kg ha−1 yr−1 higher in high-potential fields compared to low-potential fields. Tenure regime had a weak effect, mainly on phosphorus. On average, owners applied 0.37 kg ha−1 yr−1 more and exported 0.28 kg ha−1 yr−1 less phosphorus than tenants in both crops. Sulfur application and balance were weakly affected by the studied variables, and the positive balance suggests overfertilization under the assumptions of this paper. We conclude that the Argentine farming system depletes some of the main nutrients, regardless of the field's environmental potential or the land tenure system. The effect of the tenure regime is overwhelmed by the impact of environmental potential on farmers' fertilization management, with high-potential fields degrading due to soil mining at a faster pace than low-potential fields, putting future yields at risk. SIGNIFICANCEBy exploring a farming system based on nutrient depletion, our results contribute to the general understanding of tenure regime consequences on soil degradation. Argentinean farmers should consider increasing N and P application and contemplate environmental heterogeneity to avoid nutrient mining and degradation of one of the most productive areas of the world.

Convergent Adaptation of Multiple Herbicide Resistance to Auxin Mimics and ALS- and EPSPS-Inhibitors in Brassica rapa from North and South America.

Herbicide-resistant weeds have been identified and recorded on every continent where croplands are available. Despite the diversity of weed communities, it is of interest how selection has led to the same consequences in distant regions. Brassica rapa is a widespread naturalized weed that is found throughout temperate North and South America, and it is a frequent weed among winter cereal crops in Argentina and in Mexico. Broadleaf weed control is based on glyphosate that is used prior to sowing and sulfonylureas or mimic auxin herbicides that are used once the weeds have already emerged. This study was aimed at determining whether a convergent phenotypic adaptation to multiple herbicides had occurred in B. rapa populations from Mexico and Argentina by comparing the herbicide sensitivity to inhibitors of the acetolactate synthase (ALS), 5-enolpyruvylshikimate-3-phosphate (EPSPS), and auxin mimics. Five B. rapa populations were analyzed from seeds collected in wheat fields in Argentina (Ar1 and Ar2) and barley fields in Mexico (Mx1, Mx2 and MxS). Mx1, Mx2, and Ar1 populations presented multiple resistance to ALS- and EPSPS-inhibitors and to auxin mimics (2,4-D, MCPA, and fluroxypyr), while the Ar2 population showed resistance only to ALS-inhibitors and glyphosate. Resistance factors ranged from 947 to 4069 for tribenuron-methyl, from 1.5 to 9.4 for 2,4-D, and from 2.7 to 42 for glyphosate. These were consistent with ALS activity, ethylene production, and shikimate accumulation analyses in response to tribenuron-methyl, 2,4-D, and glyphosate, respectively. These results fully support the evolution of the multiple- and cross-herbicide resistance to glyphosate, ALS-inhibitors, and auxinic herbicides in B. rapa populations from Mexico and Argentina.

Population Dynamics of Digitaria sanguinalis and Effects on Soybean Crop under Different Glyphosate Application Timings

Large crabgrass (Digitaria sanguinalis) is one of the most problematic weeds in summer crops in Argentina. Emergence throughout the season of several cohorts allows the weed to escape postemergence control. Demographic models are useful tools to understand and compare the effect of different agronomic management decisions on weed population growth, as well as to identify critical functional stages that affect population growth rates. The objectives of this work were (i) to study population dynamics of D. sanguinalis in soybean, (ii) to determine the effect of glyphosate application timing on weed demographic parameters and soybean yield losses, and (iii) to evaluate the effect of weed density on soybean yield loss. A field experiment was conducted in two locations, in a completely randomized design with three replicates. Treatments included a control without glyphosate and glyphosate applied at soybean stages V4 or R1. The demographic stages (initial seedbank, seedlings, and adult plants) and parameters (establishment, survival, and fecundity) were estimated. Reproductive organs were evaluated in each cohort, including raceme per plant, spikelets per raceme, and seeds per spikelet. Weed and crop biomass and yield crop were assessed at harvest. Three cohorts were identified, the first of which emerged in November and contributed 93% of the total seedlings and 71% of the total adults. Glyphosate applied at V4 reduced the survival rate of the first cohort, as well as the total shoot biomass and the fecundity rate, increasing the biomass and crop grain yield. Both application timings affected tillers per plant, racemes per tiller, and fertile spikelets per raceme. Glyphosate at R1 did not effectively reduce weed competition, but reduced seed production as application at V4. Yield losses estimated with the model of the rectangular hyperbola according to weed density showed a yield loss at low densities (I) of 18%, and a maximum yield loss (A) of 82%. To avoid yield losses, herbicide applications targeting the first cohort are more effective than later applications targeting subsequent cohorts. However, at both times glyphosate applications reduced the number of seeds entering the seedbank, and therefore the population growth rate.

Sowing date effects on yield of three winter forage crops in the northern oasis of Mendoza

The increasing livestock farming in the province of Mendoza requests the acquisition of further knowledge on winter forage crops, annual grasses that produce a large volume of good quality biomass in a short time. The most widely used winter forage crops in Argentina are oats, rye and barley. To assess forage productivity in the northern oasis of Mendoza, an experimental factorial design combined 2 sowing dates (March 21, 2019, and April 29, 2019) and three winter forage crops: oats (Blanca Cristal INTA), rye (Lisandro INTA) and barley (Alicia INTA). Results showed no interaction between sowing dates and forage species. March sowing date was 27% more productive and offered a longer grazing period than April sowing (more than five months in March sowing and more than one month in April sowing). Oat showed the highest yield, differing significantly from rye and barley. Highlights March sowings produced more forage than April sowings. Days from sowing to first grazzing are less in March sowings.

Toxicity assessment of two IGR insecticides on eggs and larvae of the ladybird Eriopis connexa.

Eriopis connexa is an important predator in the Neotropical region, associated with pests of economic relevance on horticultural crops in Argentina. The use of broad-spectrum insecticides could reduce the biodiversity of these natural enemies in agroecosystems and put at risk its conservation. New, selective "risk reduced" insecticides could be an alternative to conventional chemical control to promote sustainable agriculture. The goal of this work was to assess the lethal and sublethal effects of two insect growth regulator (IGR) insecticides on eggs and two larval instars of E.connexa exposed to insecticides. Pyriproxyfen and cypermethrin significantly affected egg hatching by 28.8% and 70.4%, respectively. Pyriproxyfen reduced the survival of larvae that emerged by ≈52% from Day (D3)3 after hatching and caused the lengthening of developmental time for both larval and pupal stages. By contrast, teflubenzuron did not reduce hatching and survival but shortened the developmental time of the pupae stage. Cypermethrin reduced the survival of 2nd (L2 ) and 4th (L4 ) larval instars by 36.4% and 74.6%, respectively, and lengthened the development time of L2 . Pyriproxyfen lengthened the development time of L4 and reduced the fecundity and fertility of females. Teflubenzuron reduced survival of L2 and L4 larval instars by 46.9% and 28.6%, respectively, and lengthened the total development time for the larval stage. In addition, teflubenzuron reduced the fecundity and fertility of females. Both eggs and larvae were susceptible to exposure to IGR, showing lethal and sublethal effects. This study highlights, once again, the higher toxicity of cypermethrin to E.connexa. The toxicity of both IGR insecticides could impair the performance of E.connexa as a biological control agent in agroecosystems. © 2022 Society of Chemical Industry.

Spatial patterns of nutrients balance of major crops in Argentina

Argentina has a long tradition of agricultural systems that use few amounts of fertilizers. However, the crop nutrient balance remains unknown throughout the country. In this study, we estimated the nitrogen (N), phosphorus (P) and sulfur (S) balance at national and subnational scale of the six major grain crops: soybean, maize, wheat, sunflower, barley and sorghum. We found a negative spatio-temporal NPS balance with an annual average deficit of −22.4 kg ha−1 year−1 for N, −6.9 kg ha−1 year−1 for P and −2.1 kg ha−1 year−1 for S. Considering the whole agricultural area analyzed, the balance represented a mean annual negative net outflow of 612 thousand tons (kT) of N, 166 kT of P and 58 kT of S. The nutrient balance was not homogeneous across the country, with significant differences among the three major productive regions: i) the Pampean nucleus region (−32.2, −8.5, −2.92 kg ha−1 year−1, for N, P and S respectively) ii) the non-nucleus Pampean region (−14.3, −3.7, −2.03 kg ha−1 year−1 for N, P and S respectively), and iii) extra-Pampean region (−22.4, −6.3, −2.13 kg ha−1 year−1 for N, P and S respectively). Remarkably, despite having the highest N and P application rate, the Pampean nucleus region has the largest deficit of the analyzed nutrients. Soybean was the main driver of the nutrient mining in the country, accounting for 62 % of the NPS deficits at national scale (−418 kT N year−1, −120 kT P year−1 and −35 kT S year−1). Our findings suggest that the current fertilization practices applied to the major extensive crops in Argentina are far from being sufficient to supply the nutrients they demand, even cultivating soybean that is a N-fixing crop. These results highlight that Argentine main crops' high productivity is reached at the expense of soil nutrient depletion.

Could Bacillus biofilms enhance the effectivity of biocontrol strategies in the phyllosphere?

Maize (Zea mays L.), a major crop in Argentina and a staple food around the world, is affected by the emergence and re-emergence of foliar diseases. Agrochemicals are the main control strategy nowadays; however, they can cause resistance in insects and microbial pathogens and have negative effects on the environment and human health. An emerging alternative is the use of living organisms, i.e. microbial biocontrol agents, to suppress plant pathogen populations. This is a risk-free approach when the organisms acting as biocontrol agents come from the same ecosystem as the foliar pathogens they are meant to antagonize. Some epiphytic microorganisms may form biofilm by becoming aggregated and attached to a surface, as is the case of spore-forming bacteria from the genus Bacillus. Their ability to sporulate and their tolerance to long storage periods make them a frequently used biocontrol agent. Moreover, the biofilm that they create protects them against different abiotic and biotic factors and helps them to acquire nutrients, which ensures their survival on the plants they protect. This review analyzes the interactions that the phyllosphere-inhabiting Bacillus genus establishes with its environment through biofilm, and how this lifestyle could serve to design effective biological control strategies.

Pre-harvest strategy for reducing aflatoxin accumulation during storage of maize in Argentina

Maize (Zea mays L.) is an important crop in Argentina. Aspergillus flavus may infect this crop at growing stage and the harvested kernels can be contaminated with aflatoxins (AFs), whose levels may increase during storage. In Argentina, silo bags, a hermetic type of storage system, are widely used. Biocontrol based on competitive exclusion by atoxigenic A. flavus strains is a useful tool for AFs management at pre-harvest stage. The aim of the present study was to evaluate the effect of pre-harvest biocontrol treatments on aflatoxin B1 (AFB1) accumulation in maize stored in silo bags during 3 and 6 months. Three bioformulations based on A. flavus AFCHG2 and ARG5/30 strains were applied during field trials as single and mixed inocula. Harvested kernels were stored in non-hermetic and hermetic silo bags. At initial time (t0), 3 and 6 months (t3 and t6) the following parameters were evaluated: percentage of damaged kernels, moisture content, water activity, Aspergillus section Flavi incidence, relative humidity, O2 and CO2 levels into the silo bags, and AFB1 levels. The biocontrol strains included in the 3 bioformulations were able to infect maize kernels during the field trial and displaced native toxigenic isolates. At t0 control plots showed 10.9 ± 0.4 μg/kg of AFB1 while no AFs were detected in all the treatments. Along the storage assay AFB1 levels varied from not detected (<1 μg/kg) to 20.1 ± 0.8 μg/kg. Hermetic bags were better than non-hermetic bags in preventing AFB1 accumulation. Both single and mixed inocula were effective to control AFB1 accumulation in maize kernels during 3 and 6 months. AFB1 was not detected in kernels from the treatment at field stage with AFCHG2 + ARG5/30 after 6 months of storage into hermetic bags. The application of the biocontrol agents at field stage is an appropriate tool to reduce AFB1 accumulation under storage in hermetic silo bags. This is the first report on biocontrol strategy based on native atoxigenic strains applied at pre-harvest stage to reduce AFB1 accumulation during storage in Argentina.

Complete Genome Sequence of Bradyrhizobium sp. Strain C-145, a Nitrogen-Fixing Rhizobacterium Used as a Peanut Inoculant in Argentina.

ABSTRACTWe present the complete genome sequence of Bradyrhizobium sp. strain C-145, one of the most widely used nitrogen-fixing rhizobacteria for inoculating peanut crops in Argentina. The genome consists of 9.53 Mbp in a single circular chromosome and was determined using a hybrid long- and short-read assembly approach.

Infectividad micorrícica nativa en suelos de la Región Pampeana con cultivo de soja, diferentes historiales y características edáficas

The expansion of soybean crop in Argentina replaced other crops, extensive livestock and forest ecosystems. It’s unclear whether this has altered native microbial communities that could supply ecosystem services, such as arbuscular mycorrhizal fungi (AMF), symbionts of the roots of most higher plants and known to promote host nutrition and growth, and soil sustainability. However, the magnitude of the contribution by the AMFs depends, in part, on maintaining its abundance in the soil and their potential to form mycorrhizae with roots. Our objective was to analyze variations in mycorrhizal infectivity (IMS50) and in spontaneous arbuscular mycorrhizal colonization (AM) of soybean crops cropped at three agricultural sites from the north of the Pampean Region (Córdoba), in relation to the historical land use (Agricultural [soybeans for more than 60 years], Mixed agricultural-livestock [A-G, soybean in the last 35 years], and Sierras [soybean in the last 20 years]). An in vivo bioassay revealed that the highest IMS50 occurred at the Agricultural and Sierras sites, in relation to the Mixed A-G one, the site with the highest available soil P content. Both the IMS50 and AM negatively correlated with soil P, while IMS50 was negatively associated with sand content, and positively with water, carbon and clay content. A high degree of infective potential by native AMF was detected in soils destined for soybean crop at the Pampean Region with different historical land use. The IMS50 was a more sensitive detection method than the determination of AM colonization in the field. It is concluded that IMS 50 could be used to define agricultural management strategies to maintain/favor native AMF communities.

Diversity and metabolomic characterization of Penicillium expansum isolated from apples grown in Argentina and Spain

Apples (Malus domestica) are one of the most consumed fruits globally. It is a relevant crop in Argentina and Spain, and one of the main fruits for export and industrialization in these countries. Quality control of apples, fundamentally in the postharvest stage, is critical to prevent fungal diseases. The blue mould, caused by Penicillium expansum, is responsible for great economic losses due to the deterioration of the fruit and mycotoxin production. Many studies have characterized this pathogen; however, little is known about the differences between populations from distant geographical origins. The objective of the present study was to characterize two P. expansum populations, from Argentina and Spain, through morphological, metabolomic and molecular approaches, and to evaluate the existence of differences related to their geographical source. A total of 103 isolates, 53 from Argentina and 50 from Spain were studied. Their morphological features were consistent with the species description. The secondary metabolite profiles revealed low chemical diversity. All 103 isolates shared the production of 13 compounds, namely andrastins, aurantioclavine, chaetoglobosins, communesins, expansolides, roquefortine C and patulin. Penostatins and citrinin were produced by 102 and 101 isolates, respectively. A region of the β-tubulin gene was selected to analyse the diversity of the P. expansum isolates. No substantial differences were observed between isolates of different geographical origins through morphology, patulin accumulation, secondary metabolite profiles and phylogenetic analysis. However, the analysis of polymorphisms revealed 29 haplotypes with a relative separation between isolates of both populations; 13 haplotypes contained Argentinean isolates, while Spanish isolates were separated into 16 haplotypes. The diversity indices of Shannon (H’=2.075; H’=2.402) and Simpson (SiD = 0.850; SiD = 0.895) for isolates from Argentina and Spain, respectively, indicated that the diversity of P. expansum is greater in Spain than in Argentina. This distribution could be explained both by the existence of haplotype exchange between both countries, with the ancestral haplotypes originating in Spain, and the subsequent adaptation to the environmental conditions or apples varieties grown in each region.

EPPO Datasheet: Naupactus xanthographus

EPPO Datasheet: <i>Naupactus xanthographus</i>

Leafhoppers1 Associated with Citrus Orchards on the Yucatan Peninsula, Mexico

In the order Hemiptera, leafhoppers are the most diverse family, with more than 25,000 species distributed worldwide. Leafhoppers (Auchenorrhyncha: Cicadellidae) are of phytosanitary importance, because they are efficient vectors of plant pathogens such as phytoplasmas and other bacteria and viruses that cause diseases in a wide range of plants. Citrus variegated chlorosis disease is caused by the bacteria Xyllela fastidiosa (Wells et al. 1987), currently distributed and causing problems in citrus crops in Argentina, Brazil, Paraguay, and Costa Rica. However, there are only a few studies of Mexican leafhoppers associated with disease and relationship with a host plant. This research focused on taxonomy of Cicadellidae mainly on species related to citrus plants (Rutaceae). As a result, 25 leafhopper species were identified on the Peninsula of Yucatan. But, only four species, according to the literature, were associated with citrus plants: Homalodisca sp., Oncometopia clarior (Walker851), Phera obtusifrons Fowler, 1899, and Hortensia similis (Walker,1851). The rest of the leafhopper species collected, apparently used citrus plants only as temporary habitat, although some might be important pests of other crops.

Update of Argentina's Regulatory Policies on the Environmental Risk Assessment.

The Environmental Risk Assessment (ERA) of genetically modified (GM) crops in Argentina is carried out by the National Advisory Commission on Agricultural Biotechnology (CONABIA) and the Innovation and Biotechnology Coordination (CIyB). Both have a large experience with this assessment, since 1991, when CONABIA was created. The continuous support to biotechnology as a state policy and as part of the decision to encourage developers in the regulatory process has helped make progress in the revision of the regulations. The experience gained during the last 30 years and the worldwide scientific advances supported the bases to update the regulatory framework. Focusing on the biosafety strengthening and the improvement of the applicant’s experience in the GM crops evaluation process, during 2020 and 2021, the ERA went through a reviewing process. Some important modifications were made, such as (i) the assessment of stacked GM crops with focus on the possible interactions between transgenes and the expression products, (ii) the strengthening of the ERA taking into account the transportability of data and conclusions from the Confined Field Trials (CFTs), (iii) the adoption of Familiarity and History of Safe Use (HOSU) concepts on the risk assessment of the expression products, (iv) the special considerations for the unintended effects of insertional sites, and (v) as a post commercial release of GM crops, the Insect Resistance Management Plan (IRMP) was reformulated. These novel approaches enhance the ERA; they make it more efficient by applying the science criteria and the accumulated experience and scientific bibliography on the topic.

A122S, A205V, D376E, W574L and S653N substitutions in acetolactate synthase (ALS) from Amaranthus palmeri show different functional impacts on herbicide resistance.

Amaranthus palmeri S. Watson, a problematic weed infesting summer crops in Argentina, has developed multiple herbicide resistance. Resistance to acetolactate synthase (ALS)-inhibiting herbicides is particularly common, with high-level resistance mostly caused by different mutations in the ALS enzyme. Six versions of the enzyme were identified from a resistant A. palmeri population, carrying substitutions D376E, A205V, A122S, A282D, W574L and S653N. This work aims to provide a comparative analysis of these mutants and the wild-type (WT) enzyme to fully understand the herbicide resistance. Thus, all the versions of the ALS gene from A. palmeri were heterologously expressed and purified to evaluate their kinetics and inhibitory response against imazethapyr, diclosulam, chlorimuron-ethyl, flucarbazone-sodium and bispyribac-sodium. A decrease in catalytic efficiency was detected in the A205V, A122S-A282D, W574L and S653N ApALS enzymes, whereas only A205V and W574L substitutions also produced a decrease in the substrate affinity. In vitro ALS inhibition assays confirmed cross-resistance to almost all the herbicides tested, with the exception of A282D ApALS, which was as susceptible as WT ApALS. Moreover, the results confirmed that the novel substitution A122S provides cross-resistance to at least one herbicide within each of the five families of ALS inhibitors, and this property could be explained by a lower number of hydrophobic interactions between the herbicides and the mutant enzyme. This is the first report to compare various mutations in vitro from A. palmeri ALS. Our data contribute to understanding the impacts of herbicide resistance in this species. © 2021 Society of Chemical Industry.

Transgenic soy as a political crop and a resistance crop in Argentina – The struggle around control and rent appropriation between the state, seed corporations and soy farmers

Argentina is now the world’s third largest producer of transgenic crops. They grow on more than half the cultivated area of the country. Transgenic soy is not only the key crop for the Argentine economy but also for politics and society. The Argentine state and also multinational seed corporations seek to control the soy sector and appropriate rents from it, while the export-oriented soy farmers resist these attempts. To expand studies on environmental conflicts from the social to the ecological dimensions, I analyse the role of the materiality of transgenic soy in the struggles around export taxes and royalties on transgenic seeds, based on the concepts of political crops and resistance or escape crops derived from the anthropology of the state. Furthermore, I incorporate transgenic materiality into the analysis of the economic and physical materiality of political crops and resistance crops. In the case study of Argentina, I demonstrate that the materiality of transgenic soy not only enables control by the state – and in parallel by seed corporations – but that it also enables farmer resistance. Thus, transgenic soy is not only key to state building but inherently comes with the risk to the state of a powerful farmer resistance. Building on the empirical analysis, I connect the concepts of political crops and resistance crops, which have been developed for different types of plants. In the case of Argentina, there were three reasons why the state failed to control transgenic soy: 1) difficulties within the institutional setting of the state to grasp the materiality of soy; 2) the parallel governance structure of the seed corporations as developers of transgenic soy; and 3) the everyday and organised resistance of the soy farmers. For the analysis, I use qualitative and quantitative data collected during my research on transgenic agriculture in Argentina since 2009. The data are mainly analysed by applying qualitative content analysis. My own calculations based on descriptive statistics support parts of the qualitative analysis.