Identification of Rhizoctonia solani AG 1-IB in Lettuce, AG 4 HG-I in Tomato and Melon, and AG 4 HG-III in Broccoli and Spinach, in Brazil

Fungi isolated in Brazil, from lettuce, broccoli, spinach, melon and tomato, were identified as Rhizoctonia solani. All lettuce isolates anastomosed with both AG 1-IA and IB subgroups and all isolates from broccoli, spinach, melon and tomato anastomosed with AG 4 subgroup HG-I, as well as with subgroups HG-II and HG-III. DNA sequence analyses of ribosomal internal transcribed spacers showed that isolates from lettuce were AG 1-IB, isolates from tomato and melon were AG 4 HG-I, and isolates from broccoli and spinach were AG 4 HG-III. The tomato isolates caused stem rot symptoms, the spinach, broccoli and melon isolates caused hypocotyl and root rot symptoms on the respective host plants and the lettuce isolates caused bottom rot. This is the first report on the occurrence in Brazil of R. solani AG 4 HG-I in tomato and melon, of AG 4 HG-III in broccoli and spinach and of AG 1-IB in lettuce.     

Molecular detection and quantification of Colletotrichum abscissum in sweet orange propagative material

Postbloom fruit drop disease (PFD) has caused serious impacts on citrus production in the Americas, occurring sporadically and suddenly during rain in the flowering period. In São Paulo State, Brazil, Colletotrichum abscissum is the causal agent responsible for over 80% of the disease incidence. Pathogen dispersal over long distances and the origin of primary inoculum are still unclear for PFD epidemics. We tested the hypothesis that citrus propagation material can harbour C. abscissum DNA by quantifying it in leaves of budwood increase block trees (BIB) and young citrus plants (YP) using multiplex quantitative PCR (qPCR). C. abscissum DNA was detected in all citrus nurseries, regardless of the type of propagative material, the sweet orange variety, or the nursery location. Overall, 73.4% of all samples from citrus nurseries have DNA from the pathogen, with a detection limit of 10 conidia. The average of 155 conidia found in YP was higher than the conidia observed on leaf samples from BIB (p = 0.03), although leaf samples from cultivars Valencia and Pera did not differ significantly, with means around 127 and 118 conidia, respectively (p = 0.75). This is the first molecular detection of C. abscissum in citrus propagative material. The multiplex qPCR assay may be used as a protocol for an accurate diagnosis of C. abscissum in citrus propagative material, may assist a better understanding of the pathogen dispersal over long distances, and may be used for further studies involving the quantification of C. abscissum in citrus orchards.     

Intraspecific Evolution of <Emphasis Type="Italic">Rhizoctonia solani</Emphasis> AG-1 IA Associated with Soybean and Rice in Brazil based on Polymorphisms at the ITS-5.8S rDNA Operon

Rhizoctonia solani AG-1 IA causes leaf blight on soybean and rice. Despite the fact that R. solani AG-1 IA is a major pathogen affecting soybean and rice in Brazil and elsewhere in the world, little information is available on its genetic diversity and evolution. This study was an attempt to reveal the origin, and the patterns of movement and amplification of epidemiologically significant genotypes of R. solani AG-1 IA from soybean and rice in Brazil. For inferring intraspecific evolution of R. solani AG-1 IA sampled from soybean and rice, networks of ITS-5.8S rDNA sequencing haplotypes were built using the statistical parsimony algorithm from Clement et al. (2000) Molecular Ecology 9: 1657–1660. Higher haplotype diversity (Nei M 1987, Molecular Evolutionary Genetics Columbia University Press, New york: 512p.) was observed for the Brazilian soybean sample of R. solani AG-1 IA (0.827) in comparison with the rest of the world sample (0.431). Within the south-central American clade (3-2), four haplotypes of R. solani AG-1 IA from Mato Grosso, one from Tocantins, one from Maranhão, and one from Cuba occupied the tips of the network, indicating recent origin. The putative ancestral haplotypes had probably originated either from Mato Grosso or Maranhão States. While 16 distinct haplotypes were found in a sample of 32 soybean isolates of the pathogen, the entire rice sample (n=20) was represented by a single haplotype (haplotype 5), with a worldwide distribution. The results from nested-cladistic analysis indicated restricted gene flow with isolation by distance (or restricted dispersal by distance in nonsexual species) for the south-central American clade (3-2), mainly composed by soybean haplotypes.     

Organic and Conventional <Emphasis Type="Italic">Coffea arabica</Emphasis> L.: A Comparative Study of the Chemical Composition and Physiological,Biochemical and Toxicological Effects in Wistar Rats

Differentiation between organic and conventional coffee has increased due to the growing demand and high consumption of healthy foods that contain compounds with antioxidant potential, which have been associated with the reduction of chronic diseases. We used organic and conventional coffee in powder 4% (w/w) and infusions 5%, 10% and 20% (w/v) incorporated in a commercial diet to test in vivo. The levels of chlorogenic acid, caffeine and trigonelline were determined by high performance liquid chromatography. The body weight, weight gain, food consumption, aberrant foci crypt, mucin depleted foci, stress biomarkers protein carbonyl and malondialdehyde, biochemical parameters and behavior of the rats were compared between the experimental and control groups within a framework of colon carcinogenesis. The organic coffee showed higher levels of chlorogenic acid, caffeine and trigonelline than conventional, however, this difference did not significantly affect behavior. The infusions had an antioxidant effect, reducing the levels of malondialdehyde; however, the biochemical parameters of the serum were not altered, and there was neither induction nor prevention of preneoplasic lesions.