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Ribeirão Preto, Brazil

Cesarino I.,University of Campinas | Araujo P.,University of Campinas | Paes Leme A.F.,Laboratorio Nacional Of Biociencias | Creste S.,Instituto Agronomico Of Campinas | Mazzafera P.,University of Campinas
Plant Physiology and Biochemistry

Secreted class III peroxidases (EC are implicated in a broad range of physiological processes throughout the plant life cycle. However, the unambiguous determination of the precise biological role of an individual class III peroxidase isoenzyme is still a difficult task due to genetic redundancy and broad substrate specificity in vitro. In addition, many difficulties are encountered during extraction and analysis of cell wall proteins. Since class III peroxidases are also secreted into the apoplast, the use of suspension cell cultures can facilitate isolation and functional characterization of individual isoforms. Here, we report on the characterization of class III peroxidases secreted in the spent medium of sugarcane suspension cell cultures. After treatment with specific inducers of cell wall lignification, peroxidases were isolated and activities assayed with guaiacol, syringaldazine and coniferyl alcohol. Enzymatic activity was not significantly different after treatments, regardless of the substrate, with the exception of methyl-jasmonate treatment, which led to a decreased guaiacol peroxidase activity. Remarkably, peroxidases isolated from the medium were capable of oxidizing syringaldazine, an analog to sinapyl alcohol, suggesting that sugarcane cultures can produce peroxidases putatively correlated to lignification. A proteomic approach using activity staining of 2-DE gels revealed a complex isoperoxidase profile, composed predominantly of cationic isoforms. Individual spots were excised and analyzed by LC-ESI-Q-TOF and homology-based search against the Sugarcane EST Database resulted in the identification of several proteins. Spatio-temporal expression pattern of selected genes was determined for validation of identified class III peroxidases that were preferentially expressed during sugarcane stem development. © 2012 Elsevier Masson SAS. Source

Caires E.F.,State University of Ponta Grossa | Garbuio F.J.,Instituto Federal Catarinense | Churka S.,University of Sao Paulo | Joris H.A.W.,Instituto Agronomico Of Campinas
Agronomy Journal

Gypsum has been used in tropical and subtropical agriculture when subsoil acidity is an important yield-limiting factor. However, the conditions that promote increased crop yield as a result of gypsum addition in no-till (NT) systems still remain unclear. A field trial examined the effects of newly and previously surface-applied gypsum in a long-term NT system on the soil chemical properties and nutrition and yield of corn (Zea mays L.), wheat (Triticum aestivum L.), and soybean [Glycine max (L.) Merr.] on a clayey Rhodic Hapludox in Parana State, Brazil. Gypsum was surface-applied at 0 and 6 Mg ha -1 in 2004 on plots that had received gypsum previously at 0, 3, 6, and 9 Mg ha -1 in 1998. Surface-applied gypsum newly and previously improved exchangeable Ca and SO 4-S availability throughout the soil profi le, and increased the cumulative grain yield of the crops. Exchangeable K losses through leaching caused by gypsum application were low, and a larger mobility of exchangeable Mg as compared with exchangeable K in soil was found as a result of gypsum addition. An increase in Ca content in the corn, wheat, and soybean leaves, and in S content in the corn and wheat leaves occurred following the gypsum application. Th e use of gypsum showed economic viability to maximize crop grain production in a long-term NT soil with a sufficient level of exchangeable Ca (≥8 mmolc dm -3) and low levels of exchangeable Al (≤4 mmolc dm -3) and Al saturation (≤15%) in the subsoil layers (20-60 cm). © 2011 by the American Society of Agronomy. Source

Valle G.E.,Instituto Agronomico Of Campinas
Genetics and molecular research : GMR

The silverleaf whitefly (Bemisia tabaci) is actually a complex of morphologically indistinct species that vary in their capacity to transmit plant viruses and to induce physiological disorders in plants of economic importance. The worldwide impact of this whitefly has increased greatly, as it is a vector of various types of phytovirus, especially geminiviruses, in plants of economic importance. The adaptability of B. tabaci to many regions of the world has fostered the appearance of various biotypes that attack a broad spectrum of host plants. We developed microsatellite markers to study genetic variability and population structure of this whitefly in Brazil. Thirteen polymorphic microsatellite markers were isolated and characterized in 20 individuals from a natural population that were collected in soybean in Campinas (SP). The number of alleles per locus ranged from one to two, and the expected heterozygosity ranged from 0.000 to 0.505. These microsatellite markers will be useful for studies and management of B. tabaci. The low polymorphism found in these molecular markers is probably associated with homology of genes expressed in these markers. Source

Vazquez E.V.,University of La Coruna | de Abreu C.A.,Instituto Agronomico Of Campinas
Communications in Soil Science and Plant Analysis

Differences in soil phosphorus (P) contents measured by various techniques may have implications for agronomic and environmental testing. Reduced-tillage systems combined with surface manure application increase the potential risk of nutrient losses by surface runoff. A field trial was conducted to evaluate the effect of livestock slurry on nutrient accumulation at the surface layer of an acidic soil rich in organic matter with excess P levels and loamy texture. Two reduced-tillage systems, no tillage (NT) and minimum tillage (MT), and four different fertilizer treatments were assessed. The amounts of P extracted by anion-exchange resin (AER) and by Mehlich 3 (M3) were compared; in addition, differences between two determination methods of P contents extracted by Mehlich 3, namely molybdic acid colorimetric standard procedure (M3-COL) and inductively coupled plasma-mass spectroscopy (M3-ICP), were evaluated. Ninety-six soil samples were taken from the 0- to 5-cm surface layer in three successive dates after increasing manure addition. Colorimetric Mehlich 3 P ranged from 49 to 431 mg dm -3. The ranks of mean extractable soil P concentrations were AER & M3-COL & M3-ICP. The linear correlation coefficient between M3-COL and M3-ICP was highly significant (R 2 = 0.89; P & 0.01), but a two-straight-lines model or a quadratic relationship were more adequate for describing the dependence between the two determination procedures after M3 extraction. Relative and absolute differences between M3-COL and M3-ICP showed a tendency to increase as organic carbon content increased. Phosphorus content extracted by AER and M3-COL or M3-ICP reported a significant but much less predictable relationship with R 2 values of 0.27 and 0.21 (n = 96), respectively. The P in the surface layer accumulated more under NT than under MT. © 2012 Copyright Taylor and Francis Group, LLC. Source

The mitotic chromosomes of four diploid and auto-incompatible coffee species - Coffea congensis, C. eugenioides, C. liberica and C. stenophylla have been comparatively analyzed by acetic orcein, C-banding and nucleolar organizer region (NOR)-banding techniques in order to complete the chromosome characterization in the Coffea genus, by determining morphometric parameters and heterochromatin localization, and to establish karyotype traits, including the degree of symmetry/asymmetry of the karyotypes of the four studied species. The subject is of practical interest because botanical classification of coffee species is still controversial and the reported results can contribute to a better comprehension of interspecific relationships as well as of the evolutionary trends in Coffea. Some species differed from others based on some karyomorphometric parameters. The karyotype formula obtained was the same for all coffee species analyzed, 3m + 6sm + 2sms. All species displayed a moderate karyotype asymmetry and according to the Stebbins system, C. congensis and C. liberica were classified as 2A while C. eugenioides and C. stenophylla, classified as 2B, were more asymmetrical than the two former ones. Among the four indices used to assess karyotype asymmetry, Stebbins and Paszko AI indices were the best suited to individualize the species. C-bands occurred preferentially at pericentromeric/centromeric position. Two pairs of chromosomes with secondary constriction and satellite segments were observed in the species following acetic orcein staining. C. congensis, C. eugenioides and C. liberica displayed one pair of chromosomes with the NOR-band after silver staining procedure, while C. stenophylla showed two pairs. Data on morphometric chromosome and NOR-banding results were suitable for the characterization of the species. © 2013 Copyright Dipartimento di Biologia Evoluzionistica, Università di Firenze. Source

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