Renildes Lúcio Ferreira Fontes

Common bean (Phaseolus vulgaris L.) is the grain legume crop most consumed worldwide. Grain enrichment with Zn through proper crop fertilization management may contribute for ameliorating the grain quality of pulse crops. The enrichment of the common bean grain nutritional composition may potentially improve the quality of human diet, mainly in poor countries. The mean out-of-home common bean consumption per capita per day in the Brazilian population is 129 grams per day, at home, this consumption is 42 grams. The work aimed to increase the Zn concentration in common bean grains through the fertilization management of the crop in a field study. Grain nutritional quality, as related to Zn concentration, was evaluated through the application of 5 kg ha-1 to soil, at planting, and 0, 5, 10, 20 and 40 kg ha-1 Zn via foliar spray at the R8 crop stage. The Zn concentration in the grain increased from 36.63 to 52.23 mg kg-1 when the foliar dose went from zero to 40 kg ha-1. No interference of Zn on the accumulation of P, Ca, Mg and Fe in the grains was observed. The grain phytate was 4.42 g kg-1 (zero foliar Zn), increasing to 8.4, in average, with foliar spraying. The grain phytate/zinc molar ratio (Phy:Zn) increased from 12.77 (treatment with 0.0 kg ha-1 Zn) to 19.43 (median ratio for 5, 10, 20 kg ha-1 treatments), dropping to 15.58 with 40 kg ha-1 Zn. The Phy:Zn 15.58 is associated to about 30 % Zn bioavailability in the human diet.

A study was performed to evaluate the variation in pH, availability, and chemical associations of Cd in two previously contaminated Latosols amended with mineral and organic amendments. The Latosols were contaminated with Cd and amended with vermicompost, sugarcane f ilter cake, palm kernel pie, lime, phosphate rock, or zeolite. Cadmium availability was evaluated monthly in the contaminated soil/soil amendment mixtures with the DTPA and Mehlich-3 extractants for twelve months of incubation. At the end of this period, a sequential extraction procedure was performed in the mixtures to identify the Cd forms present in the several geochemical fractions. Lime immobilized Cd at a larger extension (60%), being the metal transferred to less available fractions. The Mehlich-3 extractant had a high correlation (0.96**) with the available fraction examined by the sequential extraction procedure. In general, organic amendments produced small ef fects on the f inal pH of soil/soil amendment mixtures as compared with the initial soil pH. Mineral amendments caused enhancement of soil pH and the most pronounced ef fect occurred with the use of lime.

Knowing the accumulation of nutrients in mango plants is essential for calibrating fertilization programs aiming to increase yield in nutritionally unbalanced orchards. The work aimed to evaluate mango nutritional efficiency through nutrient accumulation and partitioning in plants of Palmer cultivar grown in sand soils at São Francisco Valley, Northwest Brazil. Commercial orchards located in Bahia and Pernambuco States, Brazil, under semi-arid climate (BShw; 400-800 mm annual rainfall) had the vegetable biomass and nutrient contents in the mango compartments determined in 1, 2, 4, 7, and 12 years old plants, by evaluating four plants of each age from 20 sample units. The separated samples of the harvested trees originated the compartments roots, stems, thick twigs, thin twigs, leaves and fruits. Nutrient contents and plant dry matter per compartment were determined and plant nutrient accumulation evaluated. Biomass and fruits coefficient of biological utilization were calculated. There was increment in the accumulated content of macronutrients in the mango plants over the years, with superiority for N and K, for which there was a sharp increase as compared to the other macronutrients. Manganese and Fe were the most accumulated micronutrients in the plants over the years. The canopy of the mango Palmer plants is the compartment that accumulates more macro and micronutrients, and the partition within the canopy occurs in the sequence: leaf> thin twig> thick twig. Phosphorus and Mg, and Cu and B are the nutrients more efficient to generate plant biomass and fruit production in the mango Palmer orchards.

Cadmium (Cd²⁺) is highly harmful to plant growth. Although Cd²⁺ induces programmed cell death (PCD) in plant cells, Cd²⁺ stress in whole plants during later developmental stages and the mechanism underlying Cd²⁺‐mediated toxicity are poorly understood. Here, we showed that Cd²⁺ limits plant growth, causes intense redness in leaf vein, leaf yellowing, and chlorosis during the R1 reproductive stage of soybean (Glycine max). These symptoms were associated with Cd²⁺‐induced PCD, as Cd²⁺‐stressed soybean leaves displayed decreased number of nuclei, enhanced cell death, DNA damage, and caspase 1 activity compared to unstressed leaves. Accordingly, Cd²⁺‐induced NRPs, GmNAC81, GmNAC30 and VPE, the DCD/NRP‐mediated cell death signalling components, which execute PCD via caspase 1‐like VPE activity. Furthermore, overexpression of the positive regulator of this cell death signalling GmNAC81 enhanced sensitivity to Cd²⁺ stress and intensified the hallmarks of Cd²⁺‐mediated PCD. GmNAC81 overexpression enhanced Cd²⁺‐induced H₂O₂ production, cell death, DNA damage, and caspase‐1‐like VPE expression. Conversely, BiP overexpression negatively regulated the NRPs/GmNACs/VPE signalling module, conferred tolerance to Cd²⁺ stress and reduced Cd²⁺‐mediated cell death. Collectively, our data indicate that Cd²⁺ induces PCD in plants via activation of the NRP/GmNAC/VPE regulatory circuit that links developmentally and stress‐induced cell death.

Anatomical modifications of leaves and other organs associated with mineral nutrition have been observed in many plants. However, little is known about the quantitative effects of Si and Mn on the anatomy of plant leaves, especially in rice. This study aimed to quantify the tissue thickness of rice leaves and the density of silica bodies in rice leaves grown in a nutrient solution supplemented with Si and Mn and evaluate the possible effects of Si on Mn toxicity. Treatments were arranged in a 2×3 factorial scheme = six combinations of treatments, two doses of Si (0 and 2 mmol L-1), and three doses of Mn (0.5, 2.5, and 10 µmol L-1) in randomized complete block design with four replications. After 39 days in the nutrient solution with the respective treatments, anatomical and micromorphometric measures of the leaf blade were carried out to determine the thickness and area of leaf tissues. The data were submitted to analysis of variance (ANOVA) and Tukey’s multiple comparisons test of means(p?0,05). The abaxial and adaxial epidermal thickness, as well as the density of silica bodies increased with the addition of Si to the nutrient solution. This study demonstrated that Si reduced the number of vascular bundles and Mn reduced the thickness of the chlorenchyma with increasing doses. Manganese doses of up to 10 ?mol L-1 do not inhibit the uptake and deposition of silicon in rice leaf tissues. Higher Si concentration in the solution caused anatomical changes in the leaf, which was associated with a possible alleviation of Mn toxicity due to the higher concentration of Si in plants since this effect was observed mainly when Si was present in the nutrient solution.

The objective of this work was to evaluate the effects of the split and combinated application of foliar zinc (ZnF) + soil Zn (ZnS) on Zn concentration in the grains (ZnCG) of common bean (Phaseolus vulgaris). Two experiments were carried out in a greenhouse during two seasons. In the first experiment, two common bean cultivars received six ZnF rates (0, 120, 240, 480, 720, or 1,200 g ha^-1), with split applications at the R5, R7, and R8, or R7 and R8, or R8 plant stages. In the second experiment, one cultivar received three ZnS rates (0, 5, or 10 kg ha^-1) combined with ZnF rates (0, 1, 1.5, 3, 6, or 10 kg ha^-1). In the first experiment, with the ZnF increment, ZnCG increased linearly from 15.3 to 20.7 mg kg^-1. ZnF splitting did not affect ZnCG. In the second experiment, ZnF without ZnS did not affect ZnCG. ZnS doubled ZnCG in comparison with the treatment without ZnS application. At 5 kg ha^-1 ZnS, the highest ZnCG (67.5 mg kg^-1) was obtained with 7.8 kg ha^-1 ZnF. At 10 kg ha^-1, the highest ZnCG (66 mg kg^-1) was obtained with 4.9 kg ha^-1 ZnF. ZnF splitting is not advantageous over a single application, and the combination of ZnF and ZnS increases ZnCG in common bean, in greenhouse conditions.

The Geminiviridae family encompasses a group of single-stranded DNA viruses with twinned and quasi-isometric virions, which infect a wide range of dicotyledonous and monocotyledonous plants and are responsible for significant economic losses worldwide. Geminiviruses are divided into nine genera, according to their insect vector, host range, genome organization, and phylogeny reconstruction. Using rolling-circle amplification approaches along with high-throughput sequencing technologies, thousands of full-length geminivirus and satellite genome sequences were amplified and have become available in public databases. As a consequence, many important challenges have emerged, namely, how to classify, store, and analyze massive datasets as well as how to extract information or new knowledge. Data mining approaches, mainly supported by machine learning (ML) techniques, are a natural means for high-throughput data analysis in the context of genomics, transcriptomics, proteomics, and metabolomics. Here, we describe the development of a data warehouse enriched with ML approaches, designated geminivirus.org. We implemented search modules, bioinformatics tools, and ML methods to retrieve high precision information, demarcate species, and create classifiers for genera and open reading frames (ORFs) of geminivirus genomes. The use of data mining techniques such as ETL (Extract, Transform, Load) to feed our database, as well as algorithms based on machine learning for knowledge extraction, allowed us to obtain a database with quality data and suitable tools for bioinformatics analysis. The Geminivirus Data Warehouse (geminivirus.org) offers a simple and user-friendly environment for information retrieval and knowledge discovery related to geminiviruses.

Studies concerning the tolerance, absorption and distribution of heavy metals in plants are essential for the success of phytoremediation programs. The present study was carried out in order to evaluate the potential of the sunflower, castor bean, common buckwheat and vetiver as lead phytoaccumulators. The species were grown in nutrient solution containing increasing doses of Pb (0, 50, 100, 200 and 400 mg L^-1) during a 30-day exposure period. A completely randomized split-plot design was used, with a 4 x 5 factorial and three replicates. Significant reductions of dry matter of the root, shoot and whole plant were found in the all species under study as a function of the increased Pb doses. Vetiver showed higher tolerance to Pb contamination; sunflower and castor bean had intermediate tolerance and the common buckwheat proved to be the most sensitive species. The concentration and total content of Pb in plant compartments were significantly affected by the increased Pb doses in solution, and higher accumulation of this element was observed, in general, in the roots of the studied species. Common buckwheat proved to be not much promising for Pb-phytoremediation programs; sunflower showed potential for Pb phytoextraction and castor bean and vetiver were the most appropriate for Pb phytostabilization.

Applying micronutrients together with the herbicides used in plant desiccation can ensure an adequate supply of these nutrients and a reduction in production costs under a direct seeding (DSS) system. The aim of this study was to evaluate the effect of dosages of molybdenum (Mo), applied both in a desiccation operation together with glyphosate on the straw of brachiaria (Brachiaria brizantha) and separately via the leaves, on the common bean (cultivar Ouro Vermelho) grown under DSS. A randomised block design was used with four replications in an arrangement of sublots. In the lots, dosages of Mo (0, 0.1, 0.2, 0.4 and 0.8 kg ha-1) were applied together with the desiccant herbicide (glyphosate), and in the sublots, two dosages of Mo (0 and 100 g ha-1) were applied via the leaves. Two experiments were carried out in the town of Coimbra, in the state of Minas Gerais, Brazil, one in 2009 and the other in 2010 (the same treatments having been applied in the experimental area in 2008). Foliar fertilization was carried out with sodium molybdate [(Na2MoO4) (39% Mo)] at stage V4 in the bean plants. The application of Mo, whether mixed with the desiccant or applied via the leaves, had no significant effect on yield components or on productivity. Levels of Mo and N in the grain, and of N in the leaves, increased with the application of Mo, both when mixed with the desiccant and applied via the leaves.