Universidade Federal de Viçosa

About: Universidade Federal de Viçosa is a education organization based out in Viçosa, Brazil. It is known for research contribution in the topics: Population & Biology. The organization has 16012 authors who have published 26711 publications receiving 353416 citations.

2-Oxoglutarate: linking TCA cycle function with amino acid, glucosinolate, flavonoid, alkaloid, and gibberellin biosynthesis

Abstract: The tricarboxylic acid (TCA) cycle intermediate 2-oxoglutarate (2-OG) is used as an obligatory substrate in a range of oxidative reactions catalyzed by 2-OG-dependent dioxygenases. These enzymes are widespread in nature being involved in several important biochemical processes. We have recently demonstrated that tomato plants in which the TCA cycle enzyme 2-OG dehydrogenase (2-ODD) was antisense inhibited were characterized by early senescence and modified fruit ripening associated with differences in the levels of bioactive gibberellin (GA). Accordingly, there is now compelling evidence that the TCA cycle plays an important role in modulating the rate of flux from 2-OG to amino acid metabolism. Here we discuss recent advances in the biochemistry and molecular biology of 2-OG metabolism occurring in different biological systems indicating the importance of 2-OG and 2-OG dependent dioxygenases not only in glucosinolate, flavonoid and alkaloid metabolism but also in GA and amino acid metabolism. We additionally summarize recent findings regarding the impact of modification of 2-OG metabolism on biosynthetic pathways involving 2-ODDs.

Genetic diversity for aluminum tolerance in sorghum

Abstract: Genetic variation for aluminum (Al) tolerance in plants has allowed the development of cultivars that are high yielding on acidic, Al toxic soils. However, knowledge of intraspecific variation for Al tolerance control is needed in order to assess the potential for further Al tolerance improvement. Here we focused on the major sorghum Al tolerance gene, AltSB, from the highly Al tolerant standard SC283 to investigate the range of genetic diversity for Al tolerance control in sorghum accessions from diverse origins. Two tightly linked STS markers flanking AltSB were used to study the role of this locus in the segregation for Al tolerance in mapping populations derived from different sources of Al tolerance crossed with a common Al sensitive tester, BR012, as well as to isolate the allelic effects of AltSB in near-isogenic lines. The results indicated the existence not only of multiple alleles at the AltSB locus, which conditioned a wide range of tolerance levels, but also of novel sorghum Al tolerance genes. Transgressive segregation was observed in a highly Al tolerant breeding line, indicating that potential exists to exploit the additive or codominant effects of distinct Al tolerance loci. A global, SSR-based, genetic diversity analysis using a broader sorghum set revealed the presence of both multiple AltSB alleles and different Al tolerance genes within highly related accessions. This suggests that efforts toward broadening the genetic basis for Al tolerance in sorghum may benefit from a detailed analysis of Al tolerance gene diversity within subgroups across a target population.

Potential use of ceramic waste as precursor in the geopolymerization reaction for the production of ceramic roof tiles

Abstract: The red ceramic industry is responsible for generating high amounts of solid wastes around the world from manufacture process failures, such as ineffective firing and issues related to the products transportation. Besides the necessity of clean alternatives to discard the solid wastes, the civil construction industry has been demanding the development of better technological properties new materials. One an example of those new materials is the geopolymeric materials, characterized by the gain of mechanical strength at early ages, high fire resistance, low water absorption and refractoriness. All these characteristics imply that geopolymers are suitable for civil construction applications. The characterization of clay bricks waste, named chamotte, and its use as an alternative precursor to produce geopolymeric materials, such as roof tiles for buildings are the aims of this present work. The chemical characterization, particle size distribution, X-ray diffraction, specific mass, pozzolanic activity index (PAI) and scanning electron microscopy (SEM) were performed, in addition to the technological tests carried out on the geopolymer specimens, such as flexural strength, water absorption, linear shrinkage and apparent porosity. The chemical and mineralogical analysis proved that the waste is rich in silica and alumina, which are fundamental compounds for the geopolymers synthesis. The chamotte also has fine particles and high pozzolanic reactivity. Thus, this waste has great potential to be used as a raw material for obtaining of ceramic roof tiles by means of geopolymeric reactions.

Distribution of mycorrhizal fungal spores in soils under agroforestry and monocultural coffee systems in Brazil

Abstract: Deep-rooting trees in agroforestry systems may promote distribution of spores of arbuscular mycorrhizal fungi (AMF) at deeper soil levels. We investigated the vertical distribution of AMF spores in Oxisols under agroforestry and monocultural (unshaded) coffee systems in on-farm experiments (Brazil). The number of AMF spores was considered as an indicator of mycorrhiza incidence in soil. Spores were extracted from 0–1, 2–3, 5–7.5, 10–15, 20–30, 40–60 cm soil-depths in agroforestry and monocultural coffee systems, of three different age groups (young, medium-aged and old), using centrifugation methods, and counted. Fine roots were collected and dry-weighed from 0–30 cm in young and old systems and from several depths in medium-aged systems. Soils were characterised with respect to texture, pH, organic matter, calcium, magnesium, phosphorus and potassium. Agroforestry had a higher percentage of spores (12–21% of the total number of spores) and roots (on average 1.5 g L−1 soil) in deeper layers (20–60 cm), and a lower percentage (79–88%) closer to the surface (0–15 cm) than the monocultural fields (respectively 3–12%, 0.6 g L−1 soil and 88–97%). Greater numbers of spores in the deeper soil layers may be explained by greater amounts of roots and may be an indicator of greater incidence of mycorrhiza in agroforestry than in monocultural coffee systems. Greater mycorrhizal incidence at deeper soil layers in the agroforestry system may change the dynamics of phosphorus cycling in soil, making this nutrient more available to plants.

A PERK-like receptor kinase interacts with the geminivirus nuclear shuttle protein and potentiates viral infection.

Abstract: The nuclear shuttle protein (NSP) from bipartite geminiviruses facilitates the intracellular transport of viral DNA from the nucleus to the cytoplasm and acts in concert with the movement protein (MP) to promote the cell-to-cell spread of the viral DNA. A proline-rich extensin-like receptor protein kinase (PERK) was found to interact specifically with NSP of Cabbage leaf curl virus (CaLCuV) and of tomato-infecting geminiviruses through a yeast two-hybrid screening. The PERK-like protein, which we designated NsAK (for NSP-associated kinase), is structurally organized into a proline-rich N-terminal domain, followed by a transmembrane segment and a C-terminal serine/threonine kinase domain. The viral protein interacted stably with defective versions of the NsAK kinase domain, but not with the potentially active enzyme, in an in vitro binding assay. In vitro-translated NsAK enhanced the phosphorylation level of NSP, indicating that NSP functions as a substrate for NsAK. These results demonstrate that NsAK is an authentic serine/threonine kinase and suggest a functional link for NSP-NsAK complex formation. This interpretation was corroborated by in vivo infectivity assays showing that loss of NsAK function reduces the efficiency of CaLCuV infection and attenuates symptom development. Our data implicate NsAK as a positive contributor to geminivirus infection and suggest it may regulate NSP function.