Biogas is an alternative source of energy that contributes on reducing the emissions of polluting gas in comparison to fossil fuels as well as promoting the treatment of organic waste. However depending on the substrate used in its production, it may have a high concentration of carbon dioxide (CO2) and hydrogen sulfide (H2S); in these cases a treatment is necessary to make its use viable, for comply with current legislation and avoid damage to materials and health. Currently, the most widely used methods are physical-chemical, such as absorption, adsorption, membrane separation, and Pressure Swing Adsorption (PSA), among others. However, these methods are expensive and generate waste that needs to be treated. In this sense, biological methods have proved to be promising alternatives, especially photosynthetic processes using microalgae. This study aimed to evaluate the efficiency in removing CO2 and H2S from biogas through a bench-scale purifier prototype consisting of a photobioreactor and an absorption column, in a continuous biogas flow system. The experiment lasted 240 hours, during which 9 m³ of biogas were treated. In the first 24 hours, the flow rate was 1 L/min, resulting in an average removal of 60.8% of H2S and 20.2% of CO2. Between 24 hours and 240 hours of the study, the average biogas flow rate was 0.54 L/min, and an improvement in removal was observed, reaching 83.4% of H2S and 29.7% of CO2. The system showed efficiency in biogas treatment. However, possibilities for improvement were identified in terms of biogas flow and process, which could further enhance the results presented here.

The growing global demand for food, in addition to the environmental impacts of agricultural intensification and climate change, reinforce the need for sustainable alternatives to maintain and increase agricultural productivity. Microalgae are widely available renewable resources for application in agricultural environments. There is a vast biodiversity of microalgae species, and their versatile metabolism produces a great diversity of compounds that favor the capture and supply of nutrients, improve soil characteristics, and stimulate plant growth. In this study, we evaluated the production of indole compounds, exopolysaccharides, siderophores, and the development capacity of microalgae strains of the genera Chlamydomonas sp., Chlorella sp. and Desmodesmus sp. isolated from different Brazilian States. Microalgae that produced a greater range of compounds and developed more quickly were selected for the production of aqueous extracts from their biomass in order to evaluate their potential as a biostimulant for rice (Oryza sativa L.) plants. Seed inoculation and foliar application of extracts stimulated plant development. Shoot length in seedlings 7 days after germination was increased after the application of Syn 16 aqueous extract at concentration of 0.5 g/L. Shoots of 30-day-old plants increased in length with the application of Syn 16 and Syn 90 strains, regardless of the tested concentration, while root length was increased by Syn 16 (at both concentrations - 0.1 and 0.5 g/L) and Syn 90 (0.1 g/L). Regarding shoot dry weight, increases of up to 36 % were detected with the Syn 16 strain at concentration of 0.5 g/L. With the Syn 90 strain at a concentration of 0.5 g/L, the increase was 27 %. Furthermore, root dry weight was 43 % and 35 % higher than control plants after the application of Syn 16 and Syn 90, respectively (both at 0.5 g/L concentration). At the maturity stage, application of Syn 46 strain (0.5 g/L concentration) increased 11 % the number of full seeds per panicle when compared to control condition. Our results demonstrate the ability of microalgae extracts in stimulating the development and seed production of rice plants.

Cultivated rice (Oryza sativa L.) is frequently exposed to multiple stresses, including Schizotetranychus oryzae mite infestation. Rice domestication has narrowed the genetic diversity of the species, leading to a wide susceptibility. This work aimed to analyze the response of two African rice species (Oryza barthii and Oryza glaberrima), weedy rice (O. sativa f. spontanea), and O. sativa cv. Nipponbare to S. oryzae infestation. Surprisingly, leaf damage, histochemistry, and chlorophyll concentration/fluorescence indicated that the African species present a higher level of leaf damage, increased accumulation of H2O2, and lower photosynthetic capacity when compared to O. sativa plants under infested conditions. Infestation decreased tiller number, except in Nipponbare, and caused the death of O. barthii and O. glaberrima plants during the reproductive stage. While infestation did not affect the weight of 1,000 grains in both O. sativa, the number of panicles per plant was affected only in O. sativa f. spontanea, and the percentage of full seeds per panicle and seed length were increased only in Nipponbare. Using proteomic analysis, we identified 195 differentially abundant proteins when comparing susceptible (O. barthii) and tolerant (Nipponbare) plants under control and infested conditions. O. barthii presents a less abundant antioxidant arsenal and is unable to modulate proteins involved in general metabolism and energy production under infested condition. Nipponbare presents high abundance of detoxification-related proteins, general metabolic processes, and energy production, suggesting that the primary metabolism is maintained more active compared to O. barthii under infested condition. Also, under infested conditions, Nipponbare presents higher levels of proline and a greater abundance of defense-related proteins, such as osmotin, ricin B-like lectin, and protease inhibitors (PIs). These differentially abundant proteins can be used as biotechnological tools in breeding programs aiming at increased tolerance to mite infestation.

Advancements in genetically modified herbicide tolerance technology opened a new way to manage weed populations in crop fields. Since then, many important genetically modified crops that are tolerant to various herbicides have been developed and commercialized. Herbicides primarily act by disrupting key enzymes involved in essential metabolic or physiological processes associated with growth and development of plants. Most of the herbicide tolerant plants have been developed by introducing point mutations (non-GM approach) in the target site of herbicide action, due to the advantage of easier registration/release for commercial cultivation as well as wider public acceptance. Of the various herbicides, Imidazolinones are probably the most widely targeted ones for developing herbicide tolerant crops through non-GM approach. In rice, different mutant lines presenting amino acids changes in acetolactate synthase (ALS) have the ability to tolerate different Imidazolinones, including point mutations of Glycine to Glutamate in position 628, Serine to Asparagine in position 627, and a double mutation Tryptophan to Leucine in position 548/Serine to Isoleucine in position 627. The use of specific herbicides in combination of these mutant lines provides a reliable approach to eliminate weeds in the fields. However, the continuous overuse of a single herbicide multiple times in a growing season increases the potential risk of evolution of resistant weeds, which has become a major concern in agriculture worldwide. For this reason, the development of novel mutations in ALS (Os02g30630) to generate rice plants more tolerant to Imidazolinones than the available mutant rice lines is still a hot topic in plant-herbicide interaction field. Keeping that in mind, we carried out molecular docking experiments of Imidazolinone herbicides imazapic, imazapyr, imazaquin, and imazethapyr to evaluate the interaction of these molecules in the binding cavity of ALS from rice, being able to identify the most important amino acids responsible for the stability of these four herbicides. After introducing point mutations in these specific positions (one at a time) using Alanine scanning mutagenesis method and recalculating the effect in the affinity of herbicide-ALS interaction, we were able to propose novel amino acid residues (mainly Lysine in position 230 and Arginine in position 351) on the structure of ALS presenting a highest impact in the binding of Imidazolinones to ALS when compared to the already known amino acid mutations. This rational approach allows the researcher/farmer to choose the number of point mutations to be inserted in a rice cultivar, which will be dependent on the type of Imidazolinone used. To obtain a rice cultivar capable to tolerate the four Imidazolinone tested at the same time, we suggest six amino acid mutations at positions Val170, Phe180, Lys230, Arg351, Trp548, and Ser627 in the OsALS1.

Rice is the staple food for over half of the world's population. Infestation of Schizotetranychus oryzae (Acari: Tetranychidae) causes great losses in rice productivity. To search for rice genotypes that could better tolerate S. oryzae infestation, we evaluated morphological and production parameters in Brazilian cultivars, and identified two cultivars with contrasting responses. Leaf damage during infestation was similar for all cultivars. However, infestation in Puitá INTA-CL resulted in reduction in the number of seeds per plant, percentage of full seeds, weight of 1,000 seeds, and seed length, whereas infestation in IRGA 423 increased weight of 1,000 seeds and seed length. Reduction in seed weight per plant caused by infestation was clearly higher in Puitá INTA-CL (62%) compared to IRGA 423 (no reduction detected), thus Puitá INTA-CL was established as susceptible, and IRGA 423 as tolerant to S. oryzae infestation. Photosynthetic parameters were less affected by infestation in IRGA 423 than in Puitá INTA-CL, evidencing higher efficiency of energy absorption and use. S. oryzae infestation also caused accumulation of H2O2, decreased cell membrane integrity (indicative of cell death), and accelerated senescence in leaves of Puitá INTA-CL, while leaves of IRGA 423 presented higher levels of total phenolics compounds. We performed proteomics analysis of Puitá INTA-CL and IRGA 423 leaves after 7 days of infestation, and identified 60 differentially abundant proteins (28 more abundant in leaves of Puitá INTA-CL and 32 in IRGA 423). Proteins related to plant defense, such as jasmonate synthesis, and related to other mechanisms of tolerance such as oxidative stress, photosynthesis, and DNA structure maintenance, together with energy production and general metabolic processes, were more abundant in IRGA 423. We also detected higher levels of silicon (as amorphous silica cells) in leaves of infested IRGA 423 plants compared to Puitá INTA-CL, an element previously linked to plant defense, indicating that it could be involved in tolerance mechanisms. Taken together, our data show that IRGA 423 presents tolerance to S. oryzae infestation, and that multiple mechanisms might be employed by this cultivar. These findings could be used in biotechnological approaches aiming to increase rice tolerance to mite infestation.

OPINION article Front. Plant Sci., 13 March 2018Sec. Plant Pathogen Interactions Volume 9 - 2018 | https://doi.org/10.3389/fpls.2018.00321

OPINION article Front. Plant Sci., 24 April 2018 | https://doi.org/10.3389/fpls.2018.00556

The growing interest in the Oryza genus comes from the feasibility of studying genome evolution of these closely related species, as well as the direct impact of identifying desirable phenotypes that could be transferred to Oryza sativa, one of the world's most important cereals. Among the Oryza species, Oryza brachyantha is unique: it is highly divergent, has the smallest genome in the genus and is the only FF species, and has several traits that could be useful to improve Oryza sativa. However, our understanding of the basic biology of O. brachyantha and conservation of its diversity in germplasm are still preliminary. In this chapter, we summarize the current knowledge on O. brachyantha, especially on its recently published genomes (nuclear and chloroplastidic), basic genetics, and sequence comparisons with other Oryza species. The information gathered here should be useful to guide efforts to conserve and explore O. brachyantha diversity, a necessary step in order to achieve both basic and applied science goals in the future.

High levels of Schizotetranychus oryzae phytophagous mite infestation on rice leaves can severely affect productivity. Physiological characterization showed that S. oryzae promotes a decrease in chlorophyll concentration and the establishment of a senescence process in rice leaves. Late-infested leaves also present high levels of superoxide radical and hydrogen peroxide accumulation, along with high levels of membrane integrity loss, which is indicative of cell death. To better understand the rice molecular responses to high levels of mite infestation, we employed the Multidimensional Protein Identification Technology (MudPIT) approach to identify differentially expressed proteins. We identified 83 and 88 proteins uniquely present in control and late-infested leaves, respectively, along with 11 and one proteins more abundant in control and late-infested leaves, respectively. S. oryzae infestation induces a decreased abundance of proteins related to translation, protease inhibition, and photosynthesis. On the other hand, infestation caused increased abundance of proteins involved in protein modification and degradation. Our results also suggest that S. oryzae infestation interferes with intracellular transport, DNA structure maintenance, and amino acid and lipid metabolism in rice leaves. Proteomic data were positively correlated with enzymatic assays and RT-qPCR analysis. Our findings describe the protein expression patterns of late-infested rice leaves and suggest several targets which could be tested in future biotechnological approaches aiming to avoid the population increase of phytophagous mite in rice plants.

Abiotic stresses may result in significant losses in rice grain productivity. Protein regulation by the ubiquitin/proteasome system has been studied as a target mechanism to optimize adaptation and survival strategies of plants to different environmental stresses. This article aimed at highlighting recent discoveries about the roles ubiquitination may play in the exposure of rice plants to different abiotic stresses, enabling the development of modified plants tolerant to stress. Responses provided by the ubiquitination process include the regulation of the stomatal opening, phytohormones levels, protein stabilization, cell membrane integrity, meristematic cell maintenance, as well as the regulation of reactive oxygen species and heavy metals levels. It is noticeable that ubiquitination is a potential means for developing abiotic stress tolerant plants, being an excellent alternative to rice (and other cultures) improvement programs.

Infestation of phytophagous mite Schizotetranychus oryzae in rice causes critical yield losses. To better understand this interaction, we employed Multidimensional Protein Identification Technology (MudPIT) approach to identify differentially expressed proteins. We detected 18 and 872 unique proteins in control and infested leaves, respectively, along with 32 proteins more abundant in control leaves. S. oryzae infestation caused decreased abundance of proteins related to photosynthesis (mostly photosystem II-related), carbon assimilation and energy production, chloroplast detoxification, defense, and fatty acid and gibberellin synthesis. On the contrary, infestation caused increased abundance of proteins involved in protein modification and degradation, gene expression at the translation level, protein partitioning to different organelles, lipid metabolism, actin cytoskeleton remodeling, and synthesis of jasmonate, amino acid, and molecular chaperones. Our results also suggest that S. oryzae infestation promotes cell-wall remodeling and interferes with ethylene biosynthesis in rice leaves. Proteomic data were positively correlated with enzymatic assays and RT-qPCR analysis. Our findings describe the protein expression patterns of infested rice leaves and suggest that the acceptor side of PSII is probably the major damaged target in the photosynthetic apparatus. These data will be useful in future biotechnological approaches aiming to induce phytophagous mite resistance in rice.

Phytophagous mites (Acari) are agricultural pests that cause productivity and economic losses. Mite infestation is stressful for plants, hindering the development and harming photosynthetic structures and storage organs. In order to combat such damage, plants utilize molecular and physiological modifications, as well as the production of mite-inhibitory compounds. In this review, we focus on the main phytophagous mites that infest the most commercially important cereals - rice (Oryza sativa L.), corn (Zea mays L.) and wheat (Triticum aestivum L.) - summarizing the responses of the plants - physiological and molecular alterations - to mite infestation.

Mononychellus planki (McGREGOR, 1950) e um acaro considerado praga na cultura da soja tendo como predador natural o acaro Neoseiulus anonymus (CHANT; BAKER, 1965). Neste estudo buscou-se conhecer as caracteristicas biologicas de N. anonymus quando alimentado com M. Planki em soja transgenica e convencional em laboratorio. O estudo foi realizado a partir de ovos do predador individualizados em arenas com M. planki como alimento em soja transgenica e convencional. A duracao das fases - ovo, larva, protoninfa, deutoninfa e adulta - em dias e de 2,01±0,15, 0,56±0,24, 0,71±0,27, 2,09±0,36 e 5,34±0,38, respectivamente, para soja transgenica e de 2,04±0,28, 0,60±0,23, 0,79±0,29, 1,79±0,76 e 5,16±0,80 para soja convencional. Esse predador demonstrou alimentar-se de M. planki e desenvolver suas formas imaturas de maneira adequada com essa presa.