Identification of Species of Botryosphaeriaceae Causing Bot Gummosis in Citrus in California

Members of the Botryosphaeriaceae family are known to cause Bot gummosis on many woody plants worldwide. To identify pathogens associated with Bot gummosis on citrus in California, scion and rootstock samples were collected in 2010 and 2011 from five citrusgrowing counties in California. Symptoms observed on citrus included branch cankers, dieback, and gumming. Various fungal species were recovered from necrotic tissues of branch canker and rootstock samples. Species were identified morphologically and by phylogenetic comparison as ‘Eureka’ lemon, ‘Valencia’, ‘Washington Navel’, ‘Fukumoto’, grapefruit, ‘Satsuma’, and ‘Meyer’ lemon. Species were identified morphologically and by phylogenetic comparison of the complete sequence of the internal transcribed spacer regions, β-tubulin gene, and elongation factor α-1 genes with those of other species in GenBank. A consensus-unrooted most parsimonious tree resulting from multigene phylogenetic analysis showed the existence of three major clades in the Botryosphaeriaceae family. In total, 74 isolates were identified belonging to the Botryosphaeriaceae family, with Neofusicoccum spp., Dothiorella spp., Diplodia spp., (teleomorph Botryosphaeria), Lasiodiplodia spp., and Neoscytalidium dimidiatum (teleomorphs unknown) accounting for 39, 25, 23, 10, and 3% of the total, respectively. On inoculated Eureka lemon shoots, lesion length was significantly different (P \u3c 0.05) among 14 isolates recovered from portions of cankered tissues of the original trees. Lesion lengths were significantly longer (P \u3c 0.05) for shoots inoculated with isolates of Neofusicoccum luteum and shorter for shoots inoculated with isolates of Dothiorella viticola (P \u3c 0.05) than those of other species. Identifying the distribution and occurrence of these fungal pathogens associated with Bot gummosis is useful for management applications during occasional outbreaks in California

Deux cas béninois d’entomophthoromycoses (basidiobolomycose et conidiobolomycose) diagnostiqués en 2010 au CHU d’Angers

National audienc

Conidiobolomycose rhinofaciale avec localisations cervicales, thoraciques et brachiales : à propos d’un cas nigérian

We report here the clinical case of a Nigerian adult patient who received medical care during October 2010, at the Center for Diagnosis and Treatment of Buruli ulcer in Pobè (Benin). He presented a massive facial tumor associated with several subcutaneous (cervical, thoracic and upper limbs) nodules, evolving since several years. Tissue samples collected at Pobè medical center were addressed to the mycology and histology laboratories of Angers University Hospital (France), according to the medical exchange agreement between the two institutions about the diagnosis and treatment of Buruli ulcer disease. Histological examination showed a Splendore-Hoeppli phenomenon, consisting of a granulomatous reaction made of eosinophilic polynuclear cells surrounding rare, large and irregular, non-septate hyphae. A filamentous fungus was isolated by cultivation of the clinical samples, which was identified as Conidiobolus coronatus. The patient was treated orally with daily doses of ketoconazole (400 mg per day). After 4 months of treatment, a marked regression of the facial lesion was obtained. A first constructive facial surgery was achieved, but the patient did not attend the second step. This case report allows us to remind the mycological diagnosis of this exotic mycosis, but also to emphasize the main difficulties encountered in medical management in the developing countries

Expression of a rice chitinase gene in transgenic banana ('Gros Michel', AAA genome group) confers resistance to black leaf streak disease

Peer reviewe

Identification of Species of Botryosphaeriaceae Causing Bot Gummosis in Citrus in California

Members of the Botryosphaeriaceae family are known to cause Bot gummosis on many woody plants worldwide. To identify pathogens associated with Bot gummosis on citrus in California, scion and rootstock samples were collected in 2010 and 2011 from five citrusgrowing counties in California. Symptoms observed on citrus included branch cankers, dieback, and gumming. Various fungal species were recovered from necrotic tissues of branch canker and rootstock samples. Species were identified morphologically and by phylogenetic comparison as ‘Eureka’ lemon, ‘Valencia’, ‘Washington Navel’, ‘Fukumoto’, grapefruit, ‘Satsuma’, and ‘Meyer’ lemon. Species were identified morphologically and by phylogenetic comparison of the complete sequence of the internal transcribed spacer regions, β-tubulin gene, and elongation factor α-1 genes with those of other species in GenBank. A consensus-unrooted most parsimonious tree resulting from multigene phylogenetic analysis showed the existence of three major clades in the Botryosphaeriaceae family. In total, 74 isolates were identified belonging to the Botryosphaeriaceae family, with Neofusicoccum spp., Dothiorella spp., Diplodia spp., (teleomorph Botryosphaeria), Lasiodiplodia spp., and Neoscytalidium dimidiatum (teleomorphs unknown) accounting for 39, 25, 23, 10, and 3% of the total, respectively. On inoculated Eureka lemon shoots, lesion length was significantly different (P \u3c 0.05) among 14 isolates recovered from portions of cankered tissues of the original trees. Lesion lengths were significantly longer (P \u3c 0.05) for shoots inoculated with isolates of Neofusicoccum luteum and shorter for shoots inoculated with isolates of Dothiorella viticola (P \u3c 0.05) than those of other species. Identifying the distribution and occurrence of these fungal pathogens associated with Bot gummosis is useful for management applications during occasional outbreaks in California

Dynamics of soybean rust epidemics in sequential plantings of soybean cultivars in Nigeria

Soybean rust, caused by Phakopsora pachyrhizi, is an important foliar disease of soybean. Disease severity is dependent on several environmental factors, although the precise nature of most of these factors under field conditions is not known. To help understand the environmental factors that affect disease development, soybean rust epidemics were studied in Nigeria by sequentially planting an early-maturing, highly susceptible cultivar, TGx 1485-1D, and a late-maturing, moderately susceptible cultivar, TGx 1448-2E, at 30- to 45-day intervals from August 2004 to September 2006. Within each planting date, disease onset occurred earlier on TGx 1485-1D than on TGx 1448-2E, and rust onset was at least 20 days earlier on soybean planted between August and October than on soybean planted between November and April. The logistic model provided a better description of the temporal increase in rust severity than the Gompertz model. Based on the logistic model, the highest absolute rates of disease increase were observed on soybean planted in September 2006 and October 2004 for TGx 1485-1D and TGx 1448-2E, respectively. Disease severity as measured by the relative area under disease progress curve (RAUDPC) was significantly (P < 0.05) negatively correlated with evaporation (r = –0.73), solar radiation (r = –0.59), and temperature (r = –0.64) but positively correlated with urediniospore concentration (r = 0.58). Planting date and soybean cultivar significantly (P < 0.05) affected disease severity, with severity being higher on soybean crops planted during the wet season than those planted in the dry season. Within the wet season, planting in May and July resulted in a significantly (P < 0.05) lower RAUDPC than planting between August and October. Yields were significantly (P < 0.001) related to RAUDPC during the wet season, whereby an increase in RAUDPC resulted in a linear decrease in yield. This study suggests that selection of planting date could be a useful cultural practice for reducing soybean rust

Evaluation of soybean germplasm for resistance to soybean rust (Phakopsora pachyrhizi) in Nigeria

Soybean rust, caused by Phakopsora pachyrhizi, is one of the most important constraints to soybean production worldwide. The absence of high levels of host resistance to the pathogen has necessitated the continued search and identification of sources of resistance. In one set of experiments, 178 soybean breeding lines from the International Institute of Tropical Agriculture were rated for rust severity in the field in 2002 and 2003 at Ile-Ife, Yandev, and Ibadan, Nigeria. Thirty-six lines with disease severity ≤3 (based on a 0-to-5 scale) were selected for a second round of evaluation in 2004 at Ibadan. In the third round of evaluation under inoculated field conditions, 11 breeding lines with disease severity ≤2 were further evaluated for rust resistance at Ibadan in 2005 and 2006. The breeding lines TGx 1835-10E, TGx 1895-50F, and TGx 1903-3F consistently had the lowest level of disease severity across years and locations. In another set of experiments, 101 accessions from the United States Department of Agriculture–Agricultural Research Service and National Agriculture Research Organization (Uganda) were evaluated in the first round in 2005 under inoculated conditions in the screenhouse; 12 accessions with disease severity ≤20% leaf area infected were selected for evaluation in the second round in 2005 and 2006 under inoculated field conditions at Ibadan. Highly significant differences (P < 0.0001) in disease severity were observed among the 101 accessions during this first round of rust evaluation. Significant (P < 0.0001) differences in rust severity and sporulation also were observed among the 12 selected accessions. Accessions PI 594538A, PI 417089A, and UG-5 had significantly (P < 0.05) lower disease severity than all other selected accessions in both years of evaluation, with rust severities ranging from 0.1 to 2.4%. These results indicate that some of the breeding lines (TGx 1835-10E, TGx 1895-50F, and TGx 1903-3F) and accessions (PI 594538A, PI 417089A, and UG-5) would be useful sources of soybean rust resistance genes for incorporation into high-yielding and adapted cultivars

Interaction of soybean and Phakopsora pachyrhizi, the cause of soybean rust

Soybean rust, caused by Phakopsora pachyrhizi Syd., is a major disease limiting soybean [Glycine max (L.) Merr.] production in many areas of the world. Yield losses of up to 80% have been reported in experimental plots in Taiwan. Although the disease is not always yield limiting, it has the potential under conducive conditions to cause major losses in most soybean-producing countries in the world. The threat of P. pachyrhizi to soybean production in the Western Hemisphere began in Paraguay in 2001, where the disease was found in a limited number of soybean fields in the Parana River basin bordering Brazil. Later, in 2004, P. pachyrhizi was found in the continental USA. There are approximately 150 species in 53 genera the family Fabaceae known to be hosts of P. pachyrhizi. Approximately 120 of the known hosts occur in North and Central America and could become important in the epidemiology of the disease, serving as a bridge or overwintering host between soybean crops. The interaction between soybean genotypes and P. pachyrhizi isolates appears to follow gene-for-gene theory, with resistance genes controlling resistance to specific pathotypes. In addition to soybean, pathotype-specific resistance has also been found in a number of perennial Glycine species. Dominant genes controlling pathotypespecific resistance to soybean rust have been identified and mapped to five loci in the soybean genome, with multiple alleles at four loci. Many of the resistance genes have become ineffective over time in different geographic areas following their deployment into soybean production. The search for more durable soybean rust resistance will include research on non-host and/or engineered resistance