Potential of a Fusarium eumartii culture filtrate on the screening for wilting resistance in potato

Summary Fusarium solani f.sp. eumartii Carp. Snyder and Hansen (Fusarium eumartii) is a soil inhabitant that induces the so-called Potato Wilt and Stem End Rot disease. Prior to wilting, the pathogen induces peculiar small bronze spots on the leaflets. Failure to isolate F. eumartii from infected leaflets suggests the involvement of a toxin in the disease. The fungus was grown in liquid Richard's medium and thereafter a filtrate was obtained dialyzing (MW cutoff 12,000–14,000) and sterilizing the culture by filtration (0.22 m). Potato leaves treated with both the pathogen or the filtrate showed symptoms of bronze spots and significantly higher electrolyte leakage when compared to controls. Tomato leaves showed neither bronze spots nor electrolyte leakage after plant inoculation with the pathogen or with the filtrate treatment. Both, the absence of visible symptoms and the lack of electrolyte leakage in tomato could be associated to a certain degree of host specificity of the F. eumartii filtrate towards potato. The filtrate also induced symptoms similar to infections by F. eumartii in adult plants and in vitro plantlets of cultivars Huinkul MAG and Kennebec. Callus responses to the filtrate were related to responses of the cultivars to the pathogen in greenhouse. These results show the potential of the culture filtrate of F. eumartii for use in screening for wilting resistance.     

Inheritance of angular leaf spot resistance in common bean line BAT 332 and identification of RAPD markers linked to the resistance gene

The existence of genetic variability for angular leaf spot (ALS) resistance in the common bean germplasm allows the development of breeding lines resistant to this disease. The BAT 332 line is an important resistance source to common bean ALS. In this work we determined the inheritance pattern and identified RAPD markers linked to a resistance gene present in BAT 332. Populations F₁, F₂,BCs and BCr derived from crosses between BAT 332 and cultivar Rudá were used. Rudá is a commercial cultivar with carioca type grains and susceptible to ALS. The resistance of BAT 332 to race 61.41 of the pathogen was confirmed. Segregation analysis of the plants indicated that a single dominant gene confers resistance. For identification of RAPD markers linked to the resistance gene, bulk segregant analysis (BSA) was used. Two RAPD markers,OPAA07₉₅₀ and OPAO12₉₅₀, linked in coupling phase at 5.10 and 5.83 cM of this gene, respectively, were identified. These molecular markers are important for common bean breeders and geneticists as source of genetic information and for marker assisted selection in breeding programs. This revised version was published online in July 2006 with corrections to the Cover Date.     

Use of molecular markers to accelerate the breeding of common bean lines resistant to rust and anthracnose

The main goal of this work was to introduce resistance genes for rust, caused by Uromyces appendiculatus, and anthracnose, caused by Colletotrichum lindemuthianum, in an adapted common bean cultivar through marker-assisted backcrossing. DNA fingerprinting was used to select plants genetically closer to the recurrent parent which were also resistant to rust and to race 89 of C. lindemuthianum. DNA samples extracted from the resistant parent (cv. Ouro Negro), the recurrent parent (cv. Rudá), and from BC₁, BC₂ and BC₃ resistant plants were amplified by the RAPD technique. The relative genetic distances in relation to the recurrent parent varied between 9 and 59% for BC₁, 7 and 33% for BC₂, and 0 and 7% for BC₃ resistant plants. After only three backcrosses, five lines resistant to rust and anthracnose with, approximately, 0% genetic distance in relation to the recurrent parent were obtained. These lines underwent field yield tests in two consecutive growing seasons and three of them presented a good yield performance, surpassing in that sense their parents and most of the reference cultivars tested.     

Simulation of the Dispersion of Pollutants Using two Approaches for the Case of a Low Source in the Sbl: Evaluation of Turbulence Parameterisations

An Eulerian model and a Lagrangian particle model are used to study the dispersion of a contaminant released from a low source in the Stable Boundary Layer (SBL) using two different turbulence parameterisations. The Eulerian model is based on the solution of the advection–diffusion equation by the Laplace transform technique. The Lagrangian model is based on a generalized form of the Langevin equation. The first parameterisation, Degrazia et al. (2000), is based on Taylor’s statistical diffusion theory and the observed spectral properties, supposes a linear combination between shear and buoyancy turbulence. The second, Hanna (1982), is based on observed spectral properties from Minnesota Planetary Boundary Layer (PBL) observations and is widely used in pollutant dispersion models. Considering that these simulations are in the SBL, the analysis of the results shows a reasonably good agreement between the values computed by the models against the experimental ones for the two turbulence parameterisations.     

Canopy structure analysis for estimating forest regeneration dynamics and growth in <Emphasis Type="Italic">Nothofagus pumilio</Emphasis> forests

•Introduction   

Silviculture systems applied in Nothofagus pumilio forests are based on opening the canopy to stimulate natural regeneration by modifying light and soil moisture. The objective is to evaluate regeneration dynamics of N. pumilio along different forest canopy and solar radiation gradients.     

Macronutrient accumulation in wheat crop (Triticum aestivum L.) with Azospirillum brasilense associated with nitrogen doses and sources

Abstract

New studies are needed to optimize the nitrogen (N) amount that can be applied to utilize the Azospirillum brasilense benefits. In addition, information regarding the interaction between the urease inhibitor and biological nitrogen fixation (BNF) and how they affect the macronutrients accumulation are also needed. We evaluate the effect of N sources and doses associated with A. brasilense regarding the macronutrients accumulation in straw and grains and wheat grain yield in tropical conditions. A randomized block experimental design was used with four replications in a 2?×?5?×?2 factorial arrangement as follows: two N sources (urea and urea with urease enzyme inhibitor NBPT; five N doses (0, 50, 100, 150, and 200?kg ha^?1) applied in topdressing; with and without A. brasilense inoculation. We found that an increase in N doses positively influenced the accumulation of macronutrients in straw and grains and the wheat grain yield. N sources have similar effects. Inoculation with A. brasilense increased accumulation of Mg and S in straw and P, Ca, and Mg in grains, regardless of the N dose. The inoculation with A. brasilense associated with 140?kg ha^?1 of N increased wheat grain yield. The inoculation can contribute in a more sustainable way to wheat nutrition and optimizing N fertilization.     

The anatomy of the world's largest extinct rodent

Phoberomys is reported to be the largest rodent that ever existed, although it has been known only from isolated teeth and fragmentary postcranial bones. An exceptionally complete skeleton of Phoberomys pattersoni was discovered in a rich locality of fossil vertebrates in the Upper Miocene of Venezuela. Reliable body mass estimates yield approximately 700 kilograms, more than 10 times the mass of the largest living rodent, the capybara. With Phoberomys, Rodentia becomes one of the mammalian orders with the largest size range, second only to diprotodontian marsupials. Several postcranial features support an evolutionary relationship of Phoberomys with pakaranas from the South American rodent radiation. The associated fossil fauna is diverse and suggests that Phoberomys lived in marginal lagoons and wetlands.     

Development of transgenic fungi that kill human malaria parasites in mosquitoes

Metarhizium anisopliae infects mosquitoes through the cuticle and proliferates in the hemolymph. To allow M. anisopliae to combat malaria in mosquitoes with advanced malaria infections, we produced recombinant strains expressing molecules that target sporozoites as they travel through the hemolymph to the salivary glands. Eleven days after a Plasmodium-infected blood meal, mosquitoes were treated with M. anisopliae expressing salivary gland and midgut peptide 1 (SM1), which blocks attachment of sporozoites to salivary glands; a single-chain antibody that agglutinates sporozoites; or scorpine, which is an antimicrobial toxin. These reduced sporozoite counts by 71%, 85%, and 90%, respectively. M. anisopliae expressing scorpine and an [SM1](8):scorpine fusion protein reduced sporozoite counts by 98%, suggesting that Metarhizium-mediated inhibition of Plasmodium development could be a powerful weapon for combating malaria.