Physical resistance as a criterion in the selection of foraging material by Acromyrmex subterraneus brunneus Forel, 1911 (Hym., Formicidae)

Leaf-cutting ants forage on a wide variety of plant species using the physical and chemical characteristics of the plants as a selection criterion. In order to determine the influence of the physical factor on the selection of foraging material, inert materials such as floral sponge, polystyrene, plastic and clay, which possess different degrees of physical resistance to cutting, were offered simultaneously to five Acromyrmex subterraneus brunneus colonies, and assessed 12 and 24 h after foraging. No substrate selectivity was observed during foraging. Physical resistance was used as a decision criterion for the incorporation or return of the foraged material. This fact suggests the existence of a second time of selection of the foraged material inside the colony during cultivation of the symbiontic fungus.

Evaluation of resistance to Tomato severe rugose virus (ToSRV) in Capsicum spp. genotypes

Tomato severe rugose virus (ToSRV) is the predominant species of begomovirus in São Paulo State, Brazil, and infects primarily tomato and pepper plants. There is no information about genetic resistance of pepper to this virus, so in this work the reaction of 29 genotypes of Capsicum spp. was evaluated by inoculation of two ToSRV isolates: ToSRV-Sk (isolated from a tomato plant) and ToSRV-PJU (isolated from a pepper plant). For both isolates, two C. annuun genotypes (Catarino Cascabel - México and Silver) showed no symptoms 30 days after inoculation (d.a.i). In a second experiment, these two genotypes were evaluated for 150 d.a.i and, again, no symptoms could be observed. However, the virus was detected by RCA-PCR, indicating that both genotypes are susceptible, but less affected by ToSRV infection. Catarino Cascabel - México and Silver can be indicated for use in breeding programs for resistance of pepper to ToSRV.

Eucalyptus ESTs involved in mechanisms against plant pathogens and environmental stresses

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The field resistance of potato cultivars to foliar late blight and its relationship with foliage maturity type and skin type in Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effect of acibenzolar-S-methyl and Saccharomyces cerevisiae on the activation of Eucalyptus defences against rust

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Variation in the host preferences and responses of Ascia monuste orseis Godart (Lepidoptera: Pieridae) to cultivars of collard greens Brassica oleracea (L.) var. acephala

This work evaluated the preference of Ascia monuste orseis among 29 cultivars of collard greens through free- and no-choice assays using female adults (attractiveness and oviposition) and third-instar larvae (feeding preference), in both laboratory and greenhouse conditions. In free-choice tests with female adults, the L, V, Y, H, A, and Z cultivars produced oviposition non-preference in butterflies. Cultivars R, P, C, and D produced feeding non-preference in third-instar larvae of A. monuste orseis in free- and no-choice tests. Our findings may be useful for genetic improvement focusing on the development of B. oleracea var. acephala cultivars resistant to A. monuste orseis.

Quantitative control of Lettuce mosaic virus fitness and host defence inhibition by P1-HCPro

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The adaptive potential of a plant pathogenic fungus, Rhizoctonia solani AG-3, under heat and fungicide stress

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Leaf trait variation on Erythroxylum tortuosum (Erythroxylaceae) and its relationship with oviposition preference and stress by a host-specific leaf miner

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Peanut genes identified during initial phase of Cercosporidium personatum infection

Late leaf spot (LLS), caused by the fun.-us Cercosporidium personatum, is one of the most severe diseases in peanut (Arachis hypogaea). The vast majority of commercial cultivars do not exhibit satisfactory levels of resistance to the pathogen, whereas non-commercial genotypes cv. 850 and cv. 909 are resistant to LLS and show symptoms similar to hypersensitive response (HR) lesions. In the present study, we investigated the molecular components of the initial stages of the resistance by gene expression profiling using suppression subtractive hybridization and differential screening of cDNA macroarray techniques. Gene expression analyses have allowed us to identify more than 700 peanut unique expressed sequence taus (EST) involved in several aspects of the early stages of C. personatum pathogenesis, such as components of defense signaling pathways, gene expression regulators, cell cycle controlling genes and components of the biosynthesis of transducer and antimicrobial compounds. The most significantly induced gene corresponds to a novel O'-methyltranferase, suggesting its involvement in the production of local lesions in C. personatum-resistant A. hypogea genotypes. Taken together, our results contribute to elucidate the defense strategies of peanut and provide the framework for the generation of pathogen-resistant peanut cultivars. (C) 2007 Elsevier B.V. All rights reserved.

Caenorhabditis elegans as a model to screen plant extracts and compounds as natural anthelmintics for veterinary use

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

The anthelmintic effect of plant extracts on Haemonchus contortus and Strongyloides venezuelensis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Immunity in plants and animals: common ends through different means using similar tools

A comparative approach is potentially useful for understanding the role of mammal innate immunity role in stimulating adaptive immunity as well as the relationship between these two types of immune strategies. Considerable progress has been made in the elucidation of the co-ordinated events involved in plant perception of infection and their mobilisation of defence responses. Although lacking immunoglobulin molecules, circulating cells, and phagocytic processes, plants successfully use pre-formed physical and chemical innate defences, as well as inducible adaptive immune strategies. In the present paper, we review some shared and divergent immune aspects present in both animals and plants. (C) 2002 Elsevier B.V. All rights reserved.

Interspecific variation in the defensive responses of obligate plant-ants: experimental tests and consequences for herbivory

The aggressive behavior of ants that protect plants from herbivores in exchange for rewards such as shelter or food is thought to be an important form of biotic defense against herbivory, particularly in tropical systems. To date, however, no one has compared the defensive responses of different ant taxa associated with the same plant species, and attempted to relate these differences to longer-term efficacy of ant defense. We used experimental cues associated with herbivory-physical damage and extracts of chemical volatiles from leaf tissue-to compare the aggressive responses of two ant species obligately associated with the Amazonian myrmecophyte Tococa bullifera (Melastomataceae). We also conducted a colony removal experiment to quantify the level of resistance from herbivores provided to plants by each ant species. Our experiments demonstrate that some cues eliciting a strong response from one ant species elicited no response by the other. For cues that do elicit responses, the magnitude of these responses can vary interspecifically. These patterns were consistent with the level of resistance provided from herbivores to plants. The colony removal experiment showed that both ant species defend plants from herbivores: however, herbivory was higher on plants colonized by the less aggressive ant species. Our results add to the growing body of literature indicating defensive ant responses are stimulated by cues associated with herbivory. However, they also suggest the local and regional variation in the composition of potential partner taxa could influence the ecology and evolution of defensive mutualisms in ways that have previously remained unexplored.

Microhabitat use by Peucetia flava (Oxyopidae) on the glandular plant Rhyncanthera dichotoma (Melastomataceae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)