Plant characterization of insect-protected soybean.

Insect-protected soybean (SIP) that produces the Cry1A.105 and Cry2Ab2 insecticidal crystal proteins has been developed to provide protection from feeding damage caused by targeted lepidopteran insect pests. Typically, as part of environmental risk assessment (ERA), plant characterization is conducted, and the data submitted to regulatory agencies prior to commercialization of genetically modified (GM) crops. The objectives of this research were to: (a) compare soybean with and without the SIP trait in plant characterization field trials designed to fulfill requirements for submissions to global regulatory agencies and address China-specific considerations and (b) compare risk assessment conclusions across regions and the methodologies used in the field trials. The soybean with and without the SIP trait in temperate, tropical, and subtropical germplasm were planted in replicated multi-location trials in the USA (in 2012 and 2018) and Brazil (in 2013/2014 and 2017/2018). Agronomic, phenotypic, plant competitiveness, and survival characteristics were assessed for soybean entries with and without the SIP trait. Regardless of genetic background, growing region, season, or testing methodology, the risk assessment conclusions were the same: the evaluated insect-protected soybean did not differ from conventional soybean in evaluated agronomic, phenotypic, competitiveness, and survival characteristics indicating no change in plant pest/weed potential. These results reinforce the concept of data transportability across global regions, different seasons, germplasm, and methodologies that should be considered when assessing environmental risks of GM crops.

Genetically modified crops do not present variations in pollen viability and morphology when compared to their conventional counterparts.

Modern agricultural biotechnologies, such as those derived from genetic modification, are solutions that can enable an increase in food production, lead to more efficient use of natural resources, and promote environmental impact reduction. Crops with altered genetic materials have been extensively subjected to safety assessments to fulfill regulatory requirements prior to commercialization. The Brazilian National Technical Biosafety Commission (CTNBio) provides provisions for commercial release of transgenic crops in Brazil, including requiring information on pollen dispersion ability as part of environmental risk assessment, which includes pollen viability and morphology studies. Here we present the pollen viability and morphology of non-transgenic conventional materials, single-event genetically modified (GM) products, and stacked GM products from soybean, maize and cotton cultivated in Brazil. Microscopical observation of stained pollen grain was conducted to determine the percentage of pollen viability as well as pollen morphology, which is assessed by measuring pollen grain diameter. The pollen viability and diameter of GM soybean, maize and cotton, evaluated across a number of GM events in each crop, were similar to the conventional non-GM counterparts. Pollen characterization data contributed to the detailed phenotypic description of GM crops, supporting the conclusion that the studied events were not fundamentally different from the conventional control.

Residues of glyphosate and aminomethylphosphonic acid (AMPA) in genetically modified glyphosate tolerant soybean, corn and cotton crops / Resíduos de glifosato eácido aminometilfosfônico (AMPA) em culturas de soja, milho e algodão geneticamente modificados tolerantes ao glifosato

ABSTRACT: Glyphosate is a broad-spectrum herbicide capable of controlling a wide range of weed. It uses could cause the occurrence of residues in conventional or genetically modified crops. For this purpose, grains (soybean and corn) and cotton seeds were sampled from commercial areas in 2012/2013 to 2017/2018 seasons in different Brazilian agricultural regions to monitor glyphosate residues levels and its metabolite (aminomethylphosphonic acid - AMPA) after different managements. The glyphosate residues levels ​​in genetically modified corn (GM) ranged from no detected (ND) to 0.15 mg kg-1, in GM soybean values ​​ranged from ND to 2.81 mg kg-1 and in GM cotton ranged from ND to 1.78 mg kg-1. AMPA residues levels ​​indicated a correlation with the glyphosate residues. Glyphosate residues levels in soybean and corn grains and cotton seeds were within the Maximum Residue Limits (MRLs) established by ANVISA and Codex Alimentarius.

RESUMO: O glifosato é um herbicida de amplo espectro capaz de controlar uma grande diversidade de ervas daninhas e seu uso pode acarretar na ocorrência de resíduos, seja em culturas convencionais ou geneticamente modificadas. Sendo assim, amostragens de grãos de soja e milho e de sementes de algodão foram realizadas em áreas comerciais nas safras de 2012/2013 a 2017/2018 em diferentes regiões agrícolas brasileiras com o objetivo de monitorar os níveis de resíduos de glifosato e seu metabólito (ácido aminometilfosfônico - AMPA) após diferentes manejos. Os níveis de resíduos de glifosato em milho geneticamente modificados (GM) tolerante ao glifosato variaram desde não detectados (ND) a até 0,15 mg kg-1, em soja GM tolerante ao glifosato os valores variaram de ND a 2,81 mg kg-1 e em algodão GM tolerante ao glifosato os resultados se estabeleceram entre ND a 1,78 mg kg-1. Os valores de resíduos de AMPA indicaram correlação com os resíduos de glifosato. Os níveis de resíduos de glifosato em grãos de soja e milho e sementes de algodão ficaram dentro dos Limites Máximos de Resíduos (LMRs) preconizados pela ANVISA e Codex Alimentarius.

Field-evolved resistance to Cry1Ab maize by Spodoptera frugiperda in Brazil.

BACKGROUND: The first Bt maize in Brazil was launched in 2008 and contained the MON 810 event, which expresses Cry1Ab protein. Although the Cry1Ab dose in MON 810 is not high against fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith), MON 810 provided commercial levels of control. To support insect resistance management in Brazil, the baseline and ongoing susceptibility of FAW was examined using protein bioassays, and the level of control and life history parameters of FAW were evaluated on MON 810 maize. RESULTS: Baseline diet overlay assays with Cry1Ab (16 µg cm(-2) ) caused 76.3% mortality to field FAW populations sampled in 2009. Moderate mortality (48.8%) and significant growth inhibition (88.4%) were verified in leaf-disc bioassays. In greenhouse trials, MON 810 had significantly less damage than non-Bt maize. The surviving FAW larvae on MON 810 (22.4%) had a 5.5 day increase in life cycle time and a 24% reduction in population growth rate. Resistance monitoring (2010-2015) showed a significant reduction in Cry1Ab susceptibility of FAW over time. Additionally, a significant reduction in the field efficacy of MON 810 maize against FAW was observed in different regions from crop season 2009 to 2013. CONCLUSIONS: The decrease in susceptibility to Cry1Ab was expected, but the specific contributions to this resistance by MON 810 maize cannot be distinguished from cross-resistance to Cry1Ab caused by exposure to Cry1F maize. Technologies combining multiple novel insecticidal traits with no cross-resistance to the current Cry1 proteins and high activity against the same target pests should be pursued in Brazil and similar environments. © 2015 Society of Chemical Industry.

Functional characterization and oligomerization of a recombinant xyloglucan-specific endo-ß-1,4-glucanase (GH12) from Aspergillus niveus.

Xyloglucan is a major structural polysaccharide of the primary (growing) cell wall of higher plants. It consists of a cellulosic backbone (beta-1,4-linked glucosyl residues) that is frequently substituted with side chains. This report describes Aspergillus nidulans strain A773 recombinant secretion of a dimeric xyloglucan-specific endo-ß-1,4-glucanohydrolase (XegA) cloned from Aspergillus niveus. The ORF of the A. niveus xegA gene is comprised of 714 nucleotides, and encodes a 238 amino acid protein with a calculated molecular weight of 23.5kDa and isoelectric point of 4.38. The optimal pH and temperature were 6.0 and 60°C, respectively. XegA generated a xyloglucan-oligosaccharides (XGOs) pattern similar to that observed for cellulases from family GH12, i.e., demonstrating that its mode of action includes hydrolysis of the glycosidic linkages between glucosyl residues that are not branched with xylose. In contrast to commercial lichenase, mixed linkage beta-glucan (lichenan) was not digested by XegA, indicating that the enzyme did not cleave glucan ß-1,3 or ß-1,6 bonds. The far-UV CD spectrum of the purified enzyme indicated a protein rich in ß-sheet structures as expected for GH12 xyloglucanases. Thermal unfolding studies displayed two transitions with mid-point temperatures of 51.3°C and 81.3°C respectively, and dynamic light scattering studies indicated that the first transition involves a change in oligomeric state from a dimeric to a monomeric form. Since the enzyme is a predominantly a monomer at 60°C, the enzymatic assays demonstrated that XegA is more active in its monomeric state.

Cell wall polysaccharides from fern leaves: evidence for a mannan-rich Type III cell wall in Adiantum raddianum.

Primary cell walls from plants are composites of cellulose tethered by cross-linking glycans and embedded in a matrix of pectins. Cell wall composition varies between plant species, reflecting in some instances the evolutionary distance between them. In this work the monosaccharide compositions of isolated primary cell walls of nine fern species and one lycophyte were characterized and compared with those from Equisetum and an angiosperm dicot. The relatively high abundance of mannose in these plants suggests that mannans may constitute the major cross-linking glycan in the primary walls of pteridophytes and lycophytes. Pectin-related polysaccharides contained mostly rhamnose and uronic acids, indicating the presence of rhamnogalacturonan I highly substituted with galactose and arabinose. Structural and fine-structural analyses of the hemicellulose fraction of leaves of Adiantum raddianum confirmed this hypothesis. Linkage analysis showed that the mannan contains mostly 4-Man with very little 4,6-Man, indicating a low percentage of branching with galactose. Treatment of the mannan-rich fractions with endo-ß-mannanase produced characteristic mannan oligosaccharides. Minor amounts of xyloglucan and xylans were also detected. These data and those of others suggest that all vascular plants contain xyloglucans, arabinoxylans, and (gluco)mannans, but in different proportions that define cell wall types. Whereas xyloglucan and pectin-rich walls define Type I walls of dicots and many monocots, arabinoxylans and lower proportion of pectin define the Type II walls of commelinoid monocots. The mannan-rich primary walls with low pectins of many ferns and a lycopod indicate a fundamentally different wall type among land plants, the Type III wall.