Phylogenetic and population genetic analyses of Stagonosporopsis tanaceti, the cause of ray blight of pyrethrum in Australia

Ray blight is a destructive fungal disease of pyrethrum (Tanacetum cinerariifolium) and a major threat to the Australian pyrethrum industry; the largest producer of pyrethrum worldwide. Multi-gene phylogenies and morphological studies resulted in the recognition of three Stagonosporopsis species as the cause of ray blight on Asteraceae. Stagonosporopsis tanacetiwas described as a new species and the cause of ray blight of pyrethrum in Australia. A de novo genome assembly of paired-end Illumina reads was used to develop a multiplex set of microsatellite markers, which was further employed for temporal and geographical genetic structure analyses of S. tanaceti populations in Australia. Identification of only one mating type gene in the population, high levels of clonality and significant linkage disequilibrium suggested sexual reproduction is absent or infrequent in the Australian pyrethrum fields. Discriminant analysis of principal components (DAPC) and minimum spanning networks detected two distinct clonal lineages in the older populations; each consisting of one dominant multilocus genotype (MLG) and multiple closely-related MLGs at low frequencies. This may be indicative of introduction of two clonal lineages; which have diversified independently in the apparent absence of a sexual stage in the field. Low geographical differentiation among fields in the absence of airborne sexual spores suggests that human-mediated movement of infected seed may be a major source of long distance dispersal. A significant change in the genetic composition of the recent populations of S. tanaceti was detected, which is unlikely to be the result of mutation or recombination, and is subject to further investigation

Energy metabolism in mobile, wild-sampled sharks inferred by plasma lipids

Evaluating how predators metabolize energy is increasingly useful for conservation physiology, as it can provide information on their current nutritional condition. However, obtaining metabolic information from mobile marine predators is inherently challenging owing to their relative rarity, cryptic nature and often wide-ranging underwater movements. Here, we investigate aspects of energy metabolism in four free-ranging shark species (n = 281; blacktip, bull, nurse, and tiger) by measuring three metabolic parameters [plasma triglycerides (TAG), free fatty acids (FFA) and cholesterol (CHOL)] via non-lethal biopsy sampling. Plasma TAG, FFA and total CHOL concentrations (in millimoles per litre) varied inter-specifically and with season, year, and shark length varied within a species. The TAG were highest in the plasma of less active

A global perspective on the trophic geography of sharks

Sharks are a diverse group of mobile predators that forage across varied spatial scales and have the potential to influence food web dynamics. The ecological consequences of recent declines in shark biomass may extend across broader geographic ranges if shark taxa display common behavioural traits. By tracking the original site of photosynthetic fixation of carbon atoms that were ultimately assimilated into muscle tissues of 5,394 sharks from 114 species, we identify globally consistent biogeographic traits in trophic interactions between sharks found in different habitats. We show that populations of shelf-dwelling sharks derive a substantial proportion of their carbon from regional pelagic sources, but contain individuals that forage within additional isotopically diverse local food webs, such as those supported by terrestrial plant sources, benthic production and macrophytes. In contrast, oceanic sharks seem to use carbon derived from between 30° and 50° of latitude. Global-scale compilations of stable isotope data combined with biogeochemical modelling generate hypotheses regarding animal behaviours that can be tested with other methodological approaches.This research was conducted as part of C.S.B.’s Ph.D dissertation, which was funded by the University of Southampton and NERC (NE/L50161X/1), and through a NERC Grant-in-Kind from the Life Sciences Mass Spectrometry Facility (LSMSF; EK267-03/16). We thank A. Bates, D. Sims, F. Neat, R. McGill and J. Newton for their analytical contributions and comments on the manuscripts.Peer reviewe

The first global deep-sea stable isotope assessment reveals the unique trophic ecology of Vampire Squid Vampyroteuthis infernalis (Cephalopoda)

Vampyroteuthis infernalis Chun, 1903, is a widely distributed deepwater cephalopod with unique morphology and phylogenetic position. We assessed its habitat and trophic ecology on a global scale via stable isotope analyses of a unique collection of beaks from 104 specimens from the Atlantic, Pacific and Indian Oceans. Cephalopods typically are active predators occupying a high trophic level (TL) and exhibit an ontogenetic increase in δ15N and TL. Our results, presenting the first global comparison for a deep-sea invertebrate, demonstrate that V. infernalis has an ontogenetic decrease in δ15N and TL, coupled with niche broadening. Juveniles are mobile zooplanktivores, while larger Vampyroteuthis are slow-swimming opportunistic consumers and ingest particulate organic matter. Vampyroteuthis infernalis occupies the same TL (3.0–4.3) over its global range and has a unique niche in deep-sea ecosystems. These traits have enabled the success and abundance of this relict species inhabiting the largest ecological realm on the planet.Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. The attached file is the published pdf

First report of carrot root rot caused by Rhexocercosporidium carotae in the United States - a disease note

In March 2015, black irregularly shaped lesions up to 30 mm in diameter were observed on carrot roots that were placed in cold storage for 6 months in Wadhams, Essex County, New York. Disease incidence was ∼5% and up to 30% of the tissue was affected on some roots

Efficacy of fungicides for the control of Cercospora leaf spot in processing table beet, 2015

The experiment was conducted at the New York State Agricultural Experiment Station in Geneva, NY. The crop was planted on 22 May using a Monosem planter at the rate of 17 seeds/ft with 30 in. row spacing. Fertilizer (700 lb/A 5-5-15) was applied at planting and the herbicide Dual Magnum (0.67 pt/A) was applied directly following planting. Weed management was conducted using a mixture of machinery cultivation and by hand. On 21 Jun, 8 and 22 Jul, 50 lb/A of 22% nitrogen was applied by hand along the rows. Irrigation was provided as necessary using overhead solid-set sprinklers. Treatments were arranged in a randomized complete block design with five replications, including a nontreated control. Individual plots consisted of 20-ft sections of two adjacent rows, with a nontreated buffer of 4-ft between plots within rows. Two nontreated rows separated adjacent plots. Treatments were applied with a CO2-pressurized backpack sprayer (21.7 gal/A), with four TJ 8002VS flat fan nozzles spaced 19 in. apart along a 38 in. boom. Fungicide applications were made on 12, 19 and 24 Aug. On 8 Jul, a mycelial suspension (3 × 103 cfu/ml and 0.01% Tween-20) was applied to the two outer rows of each plot using a backpack sprayer. A second inoculation was conducted on 21 Jul during which the entire plot received a mycelial suspension of 1 × 104 cfu/ml and 0.01% Tween-20. Inoculum consisted of a mixture of eight Cercospora beticola isolates collected from diseased table beet fields in NY. Plant density (number of plants/m) was assessed prior to the application of fungicides on 25 Jun by counting the number of plants in two, 0.5 m2 lengths in each of the two inner rows of each plot. Assessments of disease intensity used an individual leaf as the sampling unit. Ten leaves were systematically selected from each of the two inner rows within each plot (n = 20/plot). Disease severity was assessed by counting the number of lesions on each leaf. Disease severity was assessed on 10 (prior to fungicide application) and 31 Aug. The effect of treatment allocation on plant density as a potential covariate and fungicides on disease severity was analyzed using a generalized linear model and means were separated by a Fisher’s protected least significant difference test (Genstat Version 17.1)

Structure of Cercospora beticola populations in organic and conventional table beet production in New York and implications for disease management

New York is the second largest producer of processing and fresh market table beet in the United States. Cercospora beticola is one of the most damaging pathogens of Beta vulgaris (sugar beet, table beet and swiss chard) worldwide, and a major limiting factor to table beet production in New York. The objective of this study was to understand the genetic diversity and structure of the C.beticola population in local table beet fields representing organic and conventional production, and investigate the presence of sexual reproduction in New York. A de novo genome assembly of C. beticola was constructed and used for identification of microsatellite loci. Eight novel microsatellite markers in addition to four previously published loci were used to genotype more than 360 isolates. The results showed significant structuring of C. beticola population in New York, and differences in the allelic and genotypic composition between production systems. The contribution of the results to better understanding the epidemiology of Cercospora leaf spot in New York and implications for disease management are discussed

A new anthracnose disease of pyrethrum caused by Colletotrichum tanaceti sp. nov.

A new pathogen of pyrethrum (Tanacetum cinerariifolium) causing anthracnose was described as Colletotrichum tanaceti based on morphological characteristics and a four-gene phylogeny consisting of rDNA-ITS, b-tubulin (TUB2), glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and actin (ACT) gene sequences. The fungus produced perithecia in culture, requiring an opposite mating type isolate in a heterothallic manner. The initial infection strategy on pyrethrum leaves involved the formation of appressoria followed by production of multilobed infection vesicles in the epidermal cells. Infection and colonization then proceeded through thinner secondary hyphae, which resulted in the initial production of water-soaked lesions followed by black necrotic lesions. The infection process was suggestive of a hemibiotrophic infection strategy. Moreover, phylogenetic analysis clearly showed that C. destructivum, C. higginsianum and C. panacicola were separate species that also had similar intracellular hemibiotrophic infection strategies as C. tanaceti, which all clustered in the C. destructivum complex. Colletotrichum spp. were detected at 1% incidence in seed of 1 of 19 seed lines, indicating the potential for seed as a source of inoculum into crops. Colletotrichum tanaceti was detected in leaf lesions from 11 of 24 pyrethrum fields surveyed between April and July 2012, at a frequency of 1.3–25.0% of lesions. Anthracnose probably contributes to the complex of foliar diseases reducing green leaf area in pyrethrum fields in Australia