Nutrients distribution in diseased coffee leaf tissue

Knowing the structure and distribution of nutrients in plant tissues can clarify some mechanisms of pathogen attack in plants and plant defense against infection, thus helping management strategies. The aim of this study was verify differences in distribution of mineral nutrients in coffee leaf tissues around foliar lesions of bacterial blight of coffee, blister spot, cercospora leaf, phoma leaf spot and coffee leaf rust. Fragments of leaf tissue surrounding the lesions were dehydrated in silica gel, carbon covered and subjected to X-ray microanalysis (MAX). Thirty-three chemical elements were detected in leaf tissue; however, there was variation in potassium and calcium contents surrounding the lesions. The highest potassium content was found in asymptomatic tissues surrounding the lesions, decreasing toward the transition zone and reaching minimum content in symptomatic tissues. The highest calcium content was found in symptomatic tissues, decreasing toward the transition zone and reaching minimum content in asymptomatic tissues. Therefore, MAX can be used to analyze the composition and distribution of nutrients in plant tissues and, if associated with mineral nutrition, it may help understand host-pathogen relationships and plant disease management.

Impact of nutritional deficiency on Yellow Sigatoka of banana

The objective of this work was to assess the incidence of Yellow Sigatoka in banana plants cultivated with deficiencies of nitrogen, phosphorus, potassium, calcium, magnesium, sulfur or boron. The experimental design was a randomized complete block with 8 treatments, 4 repetitions and 1 plant per repetition. The treatments were supplied in solution culture and consisted of all the nutrients (control) or nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulphur (S) or boron (B) deficiency. Leaves 1 and 2 were inoculated on the abaxial surface with a suspension of conidia and assessed every 5 days to with a total of 5 assessments. The average number of lesions were integrated for the area under the disease progress curve (AUDPC). The greatest AUDPC occurred in plants deficient in K, N, P, S, or Mg. Plants deficient in N, P, K, Ca, Mg, S or B had lower leaf contents of these nutrients and showed morphological changes expressed in visual deficiency symptoms. Thus, banana plants deficient in K, N, P, S or Mg had a greater incidence of Yellow Sigatoka, compared with plants with full nutrients and plants deficient Ca or B.

Induction of suppressiveness to Fusarium wilt of chrysanthemum with composted sewage sludge

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Increased carbon dioxide concentration in the air reduces the severity of Ceratocystis wilt in Eucalyptus clonal plantlets

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Occurrence of Groundnut ringspot virus on Brazilian peanut crops

A high incidence of plants with mosaic, chlorotic spots, ringspots, necrosis, smaller leaves, and stunting was observed on peanut crops (Arachis hypogaea L.) in Itapolis, So Paulo State, Brazil. Transmission electron microscope examination of thin sections of infected leaves revealed the presence of spheroidal particles, ca. 80 nm in diameter, suggestive of Tospovirus. A DNA fragment of similar to 600 bp was amplified by RT-PCR from total RNA extracted from infected tissues using primers specific for the nucleocapsid gene of Groundnut ringspot virus (GRSV). Nucleotide and deduced amino acid sequences of the fragments showed high identities with known GRSV isolates.

Identification and sequence analysis of five allexiviruses species infecting garlic crops in Brazil

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

Effects of UV-B radiation on Lecanicillium spp., biological control agents of the coffee leaf rust pathogen

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

Polyamines in tomato plants grown during an incidence of tospovirus exposure

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

Metabolic profiling by ultra-performance liquid chromatography-mass spectrometry and parallel factor analysis for the determination of disease biomarkers in Eucalyptus

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

Preliminary report of epiphytic and endophytic colonization of black oat (Avena strigosa) and wheat (Triticum aestivum) by Curtobacterium flaccumfaciens pv. flaccumfaciens in Brazil

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

The Phycodnaviridae: The Story of How Tiny Giants Rule the World

The family Phycodnaviridae encompasses a diverse and rapidly expanding collection of large icosahedral, dsDNA viruses that infect algae. These lytic and lysogenic viruses have genomes ranging from 160 to 560 kb. The family consists of six genera based initially on host range and supported by sequence comparisons. The family is monophyletic with branches for each genus, but the phycodnaviruses have evolutionary roots that connect them with several other families of large DNA viruses, referred to as the nucleocytoplasmic large DNA viruses (NCLDV).The phycodnaviruses have diverse genome structures, some with large regions of noncoding sequence and others with regions of ssDNA. The genomes of members in three genera in the Phycodnaviridae have been sequenced. The genome analyses have revealed more than 1000 unique genes, with only 14 homologous genes in common among the three genera of phycodnaviruses sequenced to date. Thus, their gene diversity far exceeds the number of so-called core genes. Not much is known about the replication of these viruses, but the consequences of these infections on phytoplankton have global affects, including influencing geochemical cycling and weather patterns.

Preface to Lesser Known Large dsDNA Viruses. Current Topics in Microbiology and Immunology 328

Several large dsDNA-containing viruses such as poxviruses (smallpox) and herpes viruses are well known among the scientific community, as well as the general populace, because they cause human diseases. The large dsDNA insect-infecting baculoviruses are also well known in the scientific community because they are used both as biological control agents and as protein expression systems. However, there are other large dsDNA-containing viruses, including the giant 1.2-Mb mimivirus, which are less well known even though all of them play important roles in everyday life. Seven of these virus families are reviewed in this book.

Signaling via cAMP in Fungi: Interconnections with Mitogen-Activated Protein Kinase Pathways

The cAMP signal transduction pathway controls a wide variety of processes in fungi. For example, considerable progress has been made in describing the involvement of cAMP pathway components in the control of morphogenesis in Saccharomyces cerevisiae, Ustilago maydis, and Magnaporthe grisea. These morphological processes include the establishment of filamentous growth in S. cerevisiae and U. maydis, and the differentiation of an appressorial infection structure in M. grisea. The discovery that appressorium formation requires cAMP signaling provides an immediate connection to fungal virulence. This connection may have broader implications among fungal pathogens because recent work indicates that cAMP signaling controls the expression of virulence traits in the human pathogen Cryptococcus neoformans. In this fungus, cAMP also influences mating, as has been found for Schizosaccharomyces pombe and as may occur in U. maydis. Finally, cAMP and mitogen- activated protein kinase pathways appear to function coordinately to control the response of certain fungi, e.g., Saccharomyces cerevisiae and Schizosaccharomyces pombe, to environmental stress. There are clues that interconnections between these pathways may be common in the control of many fungal processes.

Fourth Annual Symposium in Virology

What a pleasure it is to take part in welcoming you to this Fourth Annual Symposium in Virology. Such a tremendous program lies ahead! And how pleased and proud we are that this year's symposium is a special tribute to our colleague Dr. James Van Etten, Professor of Plant Pathology in our Institute of Agriculture and Natural Resources here at the University of Nebraska-Lincoln, who last-year was elected to membership in the National Academy of Sciences.

A Potential Plan of Action for Emerald Ash Borer in Nebraska

Abstract Emerald Ash Borer (Agrilus planipennis) (EAB) is an invasive insect pest. It feeds on the cambium tissues of ash tree species. It was first discovered in the United States in 2002 in Detroit, Michigan. Their effects on ash trees are deadly, and it is quickly spreading across the Midwest. Nebraska has not yet been invaded, but confirmed findings continue getting closer and closer. The major problem facing Nebraskans, with regards to EAB, is how to begin preparations to prevent a dramatic economic loss when an infestation does occur. So, to address this problem, I have conducted street and park tree inventories, to determine the amount of ash trees that are contained in Nebraska’s community forests; and with that data I have attempted to create a possible EAB action plan for Nebraska communities. Based on inventory findings, I have calculated that 6% of Nebraska’s community trees are ash, which is a large percentage. Then, I proposed a plan of action for communities that involve planting a diverse landscape, and a combination of ash replacement programs, and treatment for ash that are less valuable or damaged.