Sequence diversity in the coat protein gene of Lettuce big-vein associated virus and Mirafiori lettuce big-vein virus infecting lettuce in Brazil

Lettuce big vein associated virus (LBVaV) and Mirafiori lettuce big vein virus (MLBVV) have been found in mixed infection in Brazil causing the lettuce big vein disease. Analysis of part of the coat protein (CP) gene of Brazilian isolates of LBVaV collected from lettuce, showed at least 93% amino acid sequence identity with other LBVaV isolates. Genetic diversity among MLBVV CP sequences was higher when compared to LBVaV CP sequences, with amino acid sequence identity ranging between 91% to 100%. Brazilian isolates of MLBVV belong to subgroup A, with one RsaI restriction site on the coat protein gene. There is no indication for a possible geografical origin for the Brazilian isolates of LBVaV and MLBVV.

Genetic diversity of teak (Tectona grandis L.F.) from different provenances using microsatellite markers

Teak (Tectona grandis) is one of the main timber species in the world with high economic value, famous for its beauty, strength and durability. The objective of this work was to characterize the genetic diversity of teak genotypes used in Brazilian plantations. Nine microsatellite primers were used to assess 60 teak genotypes, including 33 genotypes from seeds of plantations and 14 clones from Cáceres municipality, Mato Grosso State, Brazil, and 13 clones from Honduras, Malaysia, India, Indonesia, Ivory Coast and Solomon Islands. Two groups of genotypes were detected using the Bayesian Structure analysis: 80% were placed in group 1, represented by genotypes from Cáceres and one from Malaysia, and 20% allocated in group 2, composed of clones from India, Solomon Islands, Malaysia and Honduras and the clones from the Ivory Coast. Most of the genetic variability (73%) was concentrated within groups according to AMOVA analysis. Genetic parameters were estimated for the two groups obtained in the analysis of Structure. Moderate genetic diversity was found, with 4.1 alleles per locus, on average, and an average heterozygosity of 0.329, which was lower than the expected heterozygosity (He = 0.492). Group 1 showed the lowest values for these parameters. Suggestions were made concerning the identification of contrasting genotypes to be used as parents in breeding programs.

Genetic structure and diversity of Copaifera langsdorffii Desf. in Cerrado fragments of the São Paulo State, Brazil

The loss of large areas of Cerrado (Brazilian savanna) in Brazil can lead to reduced biodiversity and to the extinction of species. Therefore, the present study aimed to investigate the genetic fragility of populations of Copaifera langsdorffii Desf exposed to different anthropic conditions in fragments of Cerrado in the state of São Paulo. The study was carried out in two Experimental Stations operated by the Forest Institute (Assis and Itirapina), in one fully protected conservation unit (Pedregulho) and in one private property (Brotas). Analyses were conducted using leaf samples from 353 adult specimens and eight pairs of microsatellite loci. The number of alleles per locus ranged from 13 to 15 in all populations, but the mean number of effective alleles was approximately half this value (7.2 to 9-1). Observed heterozygosity was significant and lower than the expected in all populations. Consequently, all populations deviated from Hardy-Weinberg expected frequencies. Fixation indexes were significant for all populations, with the Pedregulho population having the lowest value (0.189) and Itirapina having the highest (0.283). The analysis of spatial genetic structure detected family structures at distance classes of 20 to 65 m in the populations studied. No clones were detected in the populations. Estimates of effective population size were low, but the area occupied by each population studied was large enough for conservation, medium and long term. Recent reductions or bottlenecks were detected in all four populations. Mean Gst’ (genetic divergence) indicated that most of the variation was within populations. Cluster structure analysis based on the genotypes detected K= 4 clusters with distinct allele frequencies patterns. The genetic differentiation observed among populations is consistent with the hypothesis of genetic and geographic isolation. Therefore, it is essential to adopt conservation strategies that raise the gene flow between fragments.

PLANT GROWTH-PROMOTING MICROBIAL INOCULANT FOR Schizolobium parahyba pv. parahyba

ABSTRACTSchizolobium parahyba pv. amazonicum (Huber ex Ducke) Barneby (paricá) occurs naturally in the Amazon and is significant commercial importance due to its rapid growth and excellent performance on cropping systems. The aim of this paper was to evaluate a microbial inoculants such as arbuscular mycorrhiza fungi (AMF) and Rhizobium sp. that promote plant growth. The inocula was 10 g of root colonized and spores of Glomus clarum and/or 1 mL of cell suspension (107 CFU/mL) of Rhizobium sp. and/or 100 g of chemical fertilizer NPK 20-05-20 per planting hole. The experimental design was complete randomized blocks with five replications and eight treatments (n = 800). Plant height, stem diameter and plant survival were measured. The results were tested for normality and homogeneity of variances and analyzed by ANOVA and Tukey test (p < 0.05). Rhizobium sp and AM fungi showed no effect on plant growth. Environmental factors probably influenced the effectiveness of symbiosis of both microorganisms and plant growth. The chemical fertilizer increased S. parahyba growth. During the first 120 days plants suffered with drought and frost, and at 180 days plants inoculated with microorganism plus chemical fertilizer showed higher survival when compared with control. The results showed that the microbial inoculants used showed an important role on plant survival after high stress conditions, but not in plant growth. Also was concluded that the planting time should be between November to December to avoid the presence of young plants during winter time that is dry and cold.

LONG-TERM EFFECTS OF SWINE wastewater AND MINERAL FERTILIZER ASSOCIATION ON SOIL MICROBIOTA

ABSTRACT Swine wastewater (SW) application in agricultural soils may affect its microbial community in a long term. The objective of this study was to evaluate prospective changes in soil bacterial community after eight years continuous application of swine wastewater. The wastewater doses tested were 0; 100; 200 and 300 m3 ha-1, being applied from the beginning of the experiment and with or without recommended fertilization. Three soil samples were taken from each plot for determinations of basal respiration, microbial biomass and metabolic quotient. We also performed DGGE analysis and made a correlation between soil chemical conditions and microbial activity. Microbial community underwent significant structural changes from swine wastewater applications. Higher SW doses (200 and 300 m3 ha-1) influenced significantly (p <0.05) and benefitted certain bacteria groups.

Genetic diversity of bovine viral diarrhoea virus (BVDV) from Peru and Chile

Twenty-five BVDV strains, detected in serum from persistently infected cattle from Peru (n=15) and Chile (n=10) were genetically characterized. The phylogenetic analysis based on the 5' UTR showed that all 25 strains belonged to genotype 1. Twenty-three of the strains could further be subdivided into subtype 1b, and two out of ten Chilean strains into subtype 1a. In conclusion, in total 23 out of 25 strains analyzed were of genotype 1, subtype 1b. This is the predominant BVDV subtype in many countries all over the world, including USA. The close homology with previously described strains reflects the influence of livestock trade on the diversity of BVDV circulating within and between countries and continents. Peru and Chile have imported large numbers of cattle from USA and Europe, mostly with insufficient or lacking health documentation.

Genetic diversity among proso millet (Panicum miliaceum) biotypes assessed by AFLP technique

The Amplified Fragment Length Polymorphism (AFLP) technique was used to access genetic diversity between three domestic and nine wild proso millet biotypes from the United States and Canada. Eight primer combinations detected 39 polymorphic DNA fragments, with the genetic distance estimates among biotypes ranging from 0.02 to 0.04. Colorado-Weld County black seeded and Wyoming-Platte County were the most distinct biotypes according to the dissimilarity level. A UPGMA cluster analysis revealed two distinct groups of proso millet without any geographic association. Six weed biotypes exhibiting some characters of cultivated plants were grouped together with domesticated biotypes of proso millet while the three typical wild phenotypes were clearly clustered into another group according to AFLP markers.

Variations in weed population densities, rate of change and community diversity in RR-soybeans and RR-maize strip crops under two herbicide strategies

Concerns about the sustainability of large-scale, direct-drilled RR-soybeans (Glycine max), and RR-maize (Zea mays) under monoculture in central Argentina are growing steadily. An experiment was conducted during three consecutive years to determine the effects of crops and systems (monocultures and strips) and herbicide strategy on weed density, population rate of change (l), b community diversity (H´), crop yields and Land Equivalent Ratio (LER). Not only crops but also crop systems differentially influenced weed densities along their growth and development. For crop harvests, weed densities increased in both maize crop systems as compared to in the one for soybeans, but the lowest increase occurred in soybean strips. Differences were leveled by both herbicide strategies, which achieved 73% efficacy during the critical periods in both crops. l of annual monocotyledonous increased, thus shifting the weed community composition. Species richness and H´ were not affected by crop systems, but both herbicide strategies, particularly POST, either in soybeans in monoculture or in maize strips, significantly enhanced H´. Crop yields significantly increased in the maize-strip system with POST (Year 1) or PRE (Years 2 and 3) strategies, thus increasing LER above 1. Herbicide Environmental Load treatments fall within very low or low field use rating.

Mycorrhizal Association and Microbial Activity of Soil Cultivated with Cassava After Application of Mesotrione and Fluazifop-p-Butyl

Soil is a very heterogeneous environment that allows the establishment of wide range of microorganisms populations, whose balance is affected by biotic and abiotic factors. This study has aimed to assess the effect of doses of mesotrione and fluazifop-p-butyl herbicides and two assessment periods on microbial activity and biomass of soil cultivated with cassava Cacau-UFV cultivar, besides the root colonization by arbuscular mycorrhizal fungi. Two trials were conducted in a protected environment where was realized post-emergence application of mesotrione in the doses of 72, 108, 144 and 216 g ha-1 and fluazifop-p-butyl in the doses of 100, 150, 200 and 300 g ha-1, besides a control without application. Soil samples were collected for determination of soil respiratory rate (RR), microbial biomass carbon (MBC), metabolic quotient (qCO2), and colonization of roots by arbuscular mycorrhizal fungi at the 30 and 60 days after applications (DAA) of the herbicides. Fluazifop-p-butyl increased the RR, MBC and the percentage of cassava roots colonized by mycorrhizal fungi in the assessment performed at 60 DAA. The larger effects of mesotrione on soil microbial indicators were up to 30 DAA, being the changes minimized at 60 DAA. It is concluded that the herbicides alter the soil microbial indicators, with effects dependent of the product, of dose applied and also of the period of assessment.

Diversity and structure of the tree community of a fragment of tropical secondary forest of the brazilian Atlantic Forest domain 15 and 40 years after logging

Two adjacent tracts of tropical secondary forest, situated in Itambé do Mato Dentro, south-eastern Brazil, which had been regenerating for 15 and 40 years after clearing, were compared with the purpose of detecting differences in species diversity and composition, species guild composition (regeneration, stratification and dispersion), and stand structure. Four and three 1,125 m² plots laid on the 15- and 40-year-old stands, respectively, sampled 2,430 trees with diameter at the base of the stem > 5 cm. The number of species (S = 199) was high for this forest type and significantly higher for the older stand. Tree density was significantly higher in the younger stand, particularly for smaller trees, whereas the two stands did not differ in both basal area and volume per hectare. Trees of shade-tolerant and understory species were significantly more abundant in the older stand. Though sharing a large proportion of species (49%), the two stands differed significantly in the abundance of many species. Live stumps probably contributed to the relatively quick restoration of some forest characteristics, particularly species diversity, basal area and volume.

Moss diversity in the tropical rainforests of Rio de Janeiro, southeastern Brazil

Moss diversity at various sites in the Tropical Atlantic Rainforest of southeastern Brazil is high, with 338 taxa distributed among 49 families and 129 genera. Comparisons of species richness in the Tropical Atlantic Rainforest in southeastern Brazil suggest that the moss flora is not uniform, and that lowland, montane, submontane, and upper montane Atlantic rainforests have very different moss floras. Montane Atlantic Rainforest has the largest number of exclusive species and the highest species richness, Sub-Montane Atlantic Rainforest has intermediate species richness, while the Lowland Atlantic Rainforest has fewer species. The high diversity of the Montane Atlantic Rainforest could be explained by the diversity of climatic, edaphic, and physiographic changes of the vegetation. Sematophyllaceae accounted for 19% of the taxa in lowland forest, Meteoriaceae for 10% of the taxa in montane forests, and Dicranaceae for 18% of the taxa in upper montane forests. Taxa with broad Neotropical distributions (40% of the total taxa) are important elements in all the forests, while taxa restricted to Brazil comprise the second most important element in upper montane and montane forests.

Changes in plant community diversity and composition across an edge between Araucaria forest and pasture in South Brazil

This work investigated how richness, abundance, composition and structure of woody and herbaceous vegetation were altered by the proximity of an edge between Araucaria forest and pasture in South Brazil. Herbaceous and woody species including seedlings were surveyed in 42 plots of 5 × 5 m randomly placed at the following distances: 5 and 50 m from the edge into the pasture and 0, 25, 50, 100 and 250 m from the edge into the forest. There was a significant increase in vegetation cover, richness and abundance of woody species, woody seedlings and herbaceous plants at the edge (0 m). These variables, in general, decreased from 25 to 50 m from the edge into the forest in comparison to the forest interior. Few seedlings of woody plants were able to establish themselves in the pasture. There were continuous changes in species composition that occurred in the studied gradient due to the invasion of light-demanding species and the disappearance of some shade-tolerant species at the edge. In conclusion, the forest edge studied generated changes in the plant community that extended up to 50 m into the forest.

Floristic composition, diversity and structure of the "cerrado" sensu stricto on rocky soils in northern Goiás and southern Tocantins, Brazil

The "cerrado" sensu stricto is a savanna woodland physiognomy which occupies most of central Brazil, with the degree of canopy cover varying from 10% to 60% at a site with trees reaching up to seven meters high. It occurs mostly on deep and well-drained soils but can also be found on shallower ones. The diversity and structure of the "cerrado" sensu stricto on shallow and rocky Cambisols and Litosols were studied here. Sixteen 20 x 50 m² plots were sampled in a random design over patches of this vegetation in northern Goiás State and southern Tocantins. All stems from 5 cm diameter at 30 cm from the ground level were measured. Vouchers were collected and deposited at the IBGE herbarium. A total of 87 species in 65 genera and 33 families were found. Diversity index was 2.87 nats ind-1, density was 836 stems ha-1 with a basal area of 8.4374 m² ha-1. Sørensen's index indicated higher similarities between plots at the same site indicating a geographical gradient influencing the floristic composition of the "cerrado" sensu stricto on rocky soils. Czekanowski's index confirmed this trend. TWINSPAN classification final groups were defined by preferential species of more fertile soils, in opposition to those typical of dystrophic soils and to common species to gallery forests occurring on sloping terrains with gullies.

Tropical inselbergs: habitat types, adaptive strategies and diversity patterns

Inselbergs are isolated rock outcrops that rise abruptly above the surrounding plains. Granitic and gneissic inselbergs are geologically and geomorphologically old and occur throughout a broad spectrum of climatic zones. They form microclimatically and edaphically dry growth sites that support a highly specialized vegetation. Based on physiognomic criteria a number of habitat types can be distinguished that are widespread on inselbergs (e.g. ephemeral flush vegetation, monocotyledonous mats, rock pools). Three hot spots of global inselberg plant diversity can be identified which are both rich in species and endemics: a) southeastern Brazil, b) Madagascar and c) southwestern Australia.

Floristic diversity of two crystalline rocky outcrops in the Brazilian northeast semi-arid region

Floristic composition and structure of vegetation were studied in two rocky outcrop areas in the semi-arid region of northeastern Brazil. From April 2007 to September 2008, 18 monthly field trips were carried out. Vascular plants were randomly collected throughout the outcrop areas. For structural analysis, 30 plots of 1 × 1 m were set in the vegetation islands. The checklist presented combines 211 species (69 families and 168 genera), although only 56 species were collected in the plots. Fabaceae (18 spp.; 8.5%), Asteraceae (17 spp.; 8%), Orchidaceae (13 spp.; 6.1%), Euphorbiaceae (13 spp.; 6.1%), Bromeliaceae (10 spp.; 4.7%), and Poaceae (eight spp.; 3.8%) are the richest families. Overall, 1,792 shrub and herbaceous specimens were counted in the plots. The Shannon-Wiener (H) diversity index values were 2.572 and 2.547 nats individual-1. The species that presented the highest absolute abundance values (number of plants) had low frequencies in the plots and vice-versa. The biological spectrum had a high proportion of phanerophytes and therophytes, followed by cryptophytes, chamaephytes, and hemicryptophytes. The studied flora shares floristic components similar to other rocky outcrop areas of the semi-arid region in northeastern Brazil, including in relation to dominant groups in the vegetation structure.