Publications by authors named "Sylvia Morais de Sousa"

Phosphorus (P) is a critical nutrient for plant growth, yet its uptake is often hindered by soil factors like clay minerals and metal oxides such as aluminum (Al), iron (Fe), and calcium (Ca), which bind P and limit its availability. Phosphate-solubilizing bacteria (PSB) have the unique ability to convert insoluble P into a soluble form, thereby fostering plant growth. This study aimed to assess the efficacy of inoculation of B119 (rhizospheric) and B2084 (endophytic) via seed treatment in enhancing maize yield, grain P content, and enzyme activities across two distinct soil types in field conditions.

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Article Synopsis
  • Natural phosphates, although less reactive than soluble fertilizers, can enhance phosphorus bioavailability over time due to soil processes and microbial activity.
  • The study investigated the genetic diversity of soil microbiota associated with maize and sorghum when grown with different phosphate fertilizer types and doses.
  • Results showed significant changes in bacterial communities, with distinct effects of the phosphorus source on microbial populations, influencing the overall structure in the rhizosphere of both crops.
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Usage of Bacillus and Azospirillum as new eco-friendly microbial consortium inoculants is a promising strategy to increase plant growth and crop yield by improving nutrient availability in agricultural sustainable systems. In this study, we designed a multispecies inoculum containing B. thuringiensis (strain B116), B.

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Rock phosphate is an alternative form of phosphorus (P) fertilizer; however, there is no information regarding the influence of P fertilizer sources in Brazilian Cerrado soils upon microbial genes coding for phosphohydrolase enzymes in crop rhizospheres. Here, we analyze a field experiment comparing maize and sorghum grown under different P fertilization (rock phosphate and triple superphosphate) upon crop performance, phosphatase activity and rhizosphere microbiomes at three levels of diversity: small subunit rRNA marker genes of bacteria, archaea and fungi; a suite of alkaline and acid phosphatase and phytase genes; and ecotypes of individual genes. We found no significant difference in crop performance between the fertilizer sources, but the accumulation of fertilizer P into pools of organic soil P differed.

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The association between arbuscular mycorrhizal fungi (AMF) and sorghum, the fifth most cultivated cereal in the world and a staple food for many countries, is relevant to improving phosphorus (P) absorption. The importance of root exudation as a signal for the symbiosis has been shown for several species, but a complete understanding of the signaling molecules involved in the mycorrhizal symbiosis signaling pathway has not yet been elucidated. In this context, we investigated the effect of sorgoleone, one of the most studied allelochemicals and a predominant compound of root exudates in sorghum, on AMF colonization and consequently P uptake and plant growth on a sorghum genotype.

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Plant growth promoting bacteria (PGPB) are an efficient and sustainable alternative to mitigate biotic and abiotic stresses in maize. This work aimed to sequence the genome of two Bacillus strains (B116 and B119) and to evaluate their plant growth-promoting (PGP) potential in vitro and their capacity to trigger specific responses in different maize genotypes. Analysis of the genomic sequences revealed the presence of genes related to PGP activities.

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Bacterial endophytes are considered to have a beneficial effect on host plants, improving their growth by different mechanisms. The objective of this study was to investigate the capacity of four endophytic Bacillus strains to solubilize iron phosphate (Fe-P), produce siderophores and indole-acetic acid (IAA) in vitro, and to evaluate their plant growth promotion ability in greenhouse conditions by inoculation into pearl millet cultivated in a P-deficient soils without P fertilization, with Araxá rock phosphate or soluble triple superphosphate. All strains solubilized Fe-P and three of them produced carboxylate-type siderophores and high levels of IAA in the presence of tryptophan.

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Plant aldo-keto reductases of the AKR4C subfamily play key roles during stress and are attractive targets for developing stress-tolerant crops. However, these AKR4Cs show little to no activity with previously-envisioned sugar substrates. We hypothesized a structural basis for the distinctive cofactor binding and substrate specificity of these plant enzymes.

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Phosphorus (P) is an essential nutrient for plants and is acquired from the rhizosphere solution as inorganic phosphate. P is one of the least available mineral nutrients, particularly in highly weathered, tropical soils, and can substantially limit plant growth. The aim of this work was to study a possible effect of root morphology and the expression pattern of related candidate genes on P efficiency in maize.

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The aldo-keto reductases (AKRs) are classified as oxidoreductases and are found in organisms from prokaryotes to eukaryotes. The AKR superfamily consists of more than 120 proteins that are distributed throughout 14 families. Very few plant AKRs have been characterized and their biological functions remain largely unknown.

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The first step in sucrose use by maize kernels produces fructose, regardless of whether the initial reaction is catalyzed by an invertase or the reversible sucrose synthase. This fructose can enter subsequent metabolism via hexokinase, or in maize kernels, by a sorbitol dehydrogenase that reversibly converts fructose + NADH to sorbitol + NAD. High levels of SDH activity suggest that kernels synthesize considerable amounts of sorbitol, but the molecular mechanism and functional role for this process have remained equivocal.

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Maize aldose reductase (AR) is a member of the aldo-keto reductase superfamily. In contrast to human AR, maize AR seems to prefer the conversion of sorbitol into glucose. The apoenzyme was crystallized in space group P2(1)2(1)2(1), with unit-cell parameters a = 47.

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To understand the secretory mechanisms and physiological role of insulin in the tear film, the present study examined 1) the time course of insulin secretion in the tear film under glucose intravenous stimulation, 2) the glucose- and carbachol-induced insulin secretion from isolated lacrimal gland (LG), 3) the effect of insulin on glucose consumption by the cornea, and 4) the expression of insulin, pancreatic duodenal homeobox-1 (PDX-1), and glucose transport proteins (GLUTs) in LG tissue. The insulin level in the tear film of 8-wk-old male Wistar rats increased from 0.6 +/- 0.

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Context: We verified molecular alterations in a 72-year-old Brazilian male patient with a clinical course of homozygous beta-thalassemia intermedia, who had undergone splenectomy and was surviving without regular blood transfusions. The blood cell count revealed microcytic and hypochromic anemia (hemoglobin = 6.5 g/dl, mean cell volume = 74 fl, mean cell hemoglobin = 24 pg) and hemoglobin electrophoresis showed fetal hemoglobin = 1.

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