Dartanhã J. Soares

Pathogenicity and aggressiveness of Macrophomina phaseolina isolates to castor (Ricinus communis)

Charcoal rot, caused by Macrophomina phaseolina, is one of the most important diseases of castor (Ricinus communis) in the growing regions of Northeastern Brazil, particularly in the State of Bahia, which concentrates 65% of the countrys production. The pathogenicity and aggressiveness of the charcoal rot pathogen was assessed in twenty-seven isolates of M. phaseolina obtained from six plant species: Ricinus communis (n=21), Gossypium hirsutum (n=2), Sesamum indicum (n=1), Helianthus annuus (n=1), Jatropha gossypifolia (n=1) and Arachis hypogaea (n=1). All isolates were pathogenic and exhibited a range of aggressiveness towards BRS Energia cultivar regardless of their host of origin.

Plasmopara invertifolia sp. nov. causing downy mildew on Helichrysum bracteatum (Asteraceae)

Plasmopara invertifolia sp. nov. causes severe leaf distortion and necrosis on Helichrysum bracteatum, a beautiful and important ornamental plant for trade in Brazil. This oomycete pathogen is distinguished from other species of Plasmopara on Asteraceae by its smaller sporangia and larger sporangiophores, which justifies the proposition of a new taxon in the genus Plasmopara to accommodate it. The phylogenetic analysis of cox2 gene sequence data supports such placement and also shows that P. invertifolia is close to the P. halstedii complex. Plasmopara invertifolia is then described, illustrated and discussed.

Dichotomophthora sp. causing leaf spot and foliar abscission on Anredera cordifolia in Brazil

Dichotomophthora sp. is described as causing leaf spot and early foliar abscission on Anredera cordifolia in Brazil. Morphologically, the fungus fits with D. lutea, however, ITS sequence showed high homology with Bipolaris sp. recorded on Basella alba in Florida and with D. portulacae recorded on B. rubra in China. Additional studies are needed to clarify the taxonomic status of Dichotomophthora species on members of Basellaceae.

Pyriculariopsis calatheae sp. nov., a novel anamorphic hyphomycete from the Atlantic forest of Brazil causing leaf spots on Calathea longifolia

The new species Pyriculariopsis calatheae is described causing leaf spots on Calathea longifolia (Marantaceae). It represents an addition to the mycobiota of the tropical seasonal semi-deciduous montane forest, a component of the Brazilian Atlantic forest and a highly threatened ecosystem.

First report of Oidium heliotropii-indici on Heliotropium indicum from Brazil

A powdery mildew fungus belonging to the genus Oidium subgen. Fibroidium was found on Heliotropium indicum in north-east Brazil. This fungus was identified as Oidium heliotropii-indici and is described for the first time on this host from Brazil.

Alternaria leaf spot, caused by Alternaria thunbergiae, recorded for the first time on Thunbergia alata from Brazil

Alternaria thunbergiae is recorded as the cause of leaf spots on Thunbergia alata (Acanthaceae), for the first time from Brazil.

Bayesian analyses of five gene regions reveal a new phylogenetic species of Macrophomina associated with charcoal rot on oilseed crops in Brazil

Macrophomina is a genus belonging to Botryosphaeriaceae that comprises well-known necrotrophic pathogens related to hundreds of plant hosts around the world. Historically, M. phaseolina is the causal agent of charcoal rot in several crops, mainly in tropical and subtropical areas around the world. However, after a recent genetic diversity study using morphological and molecular approaches, which resulted in the epitypification of M. phaseolina, and the description of a new Macrophomina species associated with charcoal rot disease, the hypothesis that other cryptic species could be present under the name M. phaseolina was raised. Previous studies in Brazil revealed a high genetic diversity and different levels of aggressiveness of M. phaseolina isolates associated with charcoal rot in oilseed crops. Thus, the aim of the present study was, through phylogenetic and morphological studies, to determine if isolates of Macrophomina obtained from different oilseed crops represent a single species or distinct taxa. Based on the results obtained, it was possible to identify three different Macrophomina species: M. phaseolina, M. pseudophaseolina and a new phylogenetic species, M. euphorbiicola. This is first report of M. pseudophaseolina in Brazil causing charcoal rot on Arachis hypogaea, Gossypium hirsutum and Ricinus communis and associated with seed decay of Jatropha curcas. In addition, a novel species described in the present study, M. euphorbiicola, is reported as the etiological agent of the charcoal rot on R. communis and Jatropha gossypifolia.

Lasiodiplodia hormozganensis causing basal stem rot on Ricinus communis in Brazil

Ricinus communis plants showing symptoms of root and stem rot were observed in the states of Bahia and Paraíba, Brazil. Based on the morphology and phylogenetic analyses of ITS and TEF-1α combined, the causal agents of the observed symptoms were identified as Lasiodiplodia hormozganensis and L. theobromae, pathogenicity was confirmed by fulfilling Koch’s postulates. To our knowledge, this is the first report from any part of the world of L. hormozganensis causing root and stem rot in R. communis.

Amphobotrys ricini causing gray mold on Acalypha herzogiana in Brazil

Amphobotrys ricini is reported for the first time causing gray mold on the ornamental plant Acalypha herzogiana. This new host-pathogen association record is based on collections made at two localities in Brazil. Morphology of the fungus is described herein and its pathogenicity to A. hezorgiana and Ricinus communis was demonstrated.

Calidion bombacis, a new combination for Uredo bombacis with the record of Bombacopsisglabra (Bombacaceae) as a new host from Brazil

The new combination Calidion bombacis is proposed for the rust species formerly known as Uredo bombacis. This nomenclatural change is based on the examination of newly collected material of this fungus from a new host, Bombacopsis glabra from Brazil, and reexamination of the isotype. Until now this fungus was only known to occur in Asia (China, India and Sri Lanka). Therefore, this is also the first record of this fungus from the Neotropics.