Academic literature on the topic 'Dothistroma spp'

Dothistroma needle blight, caused by Dothistroma septospora (teleo-morph Mycosphaerella pini), is a serious foliage disease of pine species throughout the world. In the northeastern United States, the fungus has been reported from Pennsylvania, but not New York, New Jersey, or any of the New England states. It has been reported from the eastern provinces of Canada (Newfoundland, Quebec). During 1994 to 1998, stromatic conidomata consistent with descriptions of D. septospora were associated with needle blight symptoms on mature landscape pines at four locations (Jericho, Montpelier, Williamstown, Williston) and one Christmas tree farm (Barre) in Vermont. Pinus nigra was affected at four locations; P. mugo and P. ponderosa were affected at one location each. Severe foliar blight and defoliation occurred during successive years on P. nigra and P. mugo. Collections from each location and host were examined microscopically. Mean lengths and widths of 20 or more conidia from each of three collections of P. nigra (Barre, Montpelier, and Williston) were 2.3 × 25, 2.7 × 20, and 2.6 × 24 μm, respectively. Corresponding values for collections from P. mugo and P. ponderosa were 2.4 × 26 and 3.6 × 31 μm, respectively. All collections conformed to descriptions and illustrations of D. septospora (1). No ascigerous state was observed from 1994 to 1998. This is the first report of D. septospora in New England. Reference: (1) H. C. Evans. 1984. The Genus Mycosphaerella and Its Anamorphs Cercoseptoria, Dothistroma and Lecanosticta on Pines. Commonwealth Mycological Institute, Kew, England.

Globally, pitch canker and Dothistroma needle blight are two of the most important diseases of pine species caused, respectively, by the pathogens Fusarium circinatum Nirenberg & O’Donnell and Dothistroma spp. ( Dothistroma septosporum (Dorog.) Morelet and Dothistroma pini Hulbary). The potential distributions of these two diseases under current global climate have previously been modelled and contrast strongly with each other. In this study, we used the process-based niche model CLIMEX to estimate the potential distribution of both diseases in the 2080s under six scenarios that include three contrasting global climate models, each with moderate and high CO2 emissions. For both diseases, under the future climate scenarios, there was a global reduction in the potentially suitable area. Among the three global climate models, this reduction ranged from 11% to 22% for Dothistroma needle blight and from 39% to 58% for pitch canker. The projected potential ranges of both diseases were significantly reduced for Africa, South America, and Australia. In Asia and North America, substantial reductions in potential area were generally projected for pitch canker, while little change to moderate levels of expansion were projected for Dothistroma needle blight. For Europe and New Zealand, expansion of suitable climate was projected under all climate change scenarios for both diseases.

Dothistroma needle blight (DNB), caused by Dothistroma septosporum and Dothistroma pini, is the most important forest disease of pine in many countries. This disease has recently emerged in Ukraine as a major threat to mostly Pinus nigra subsp. pallasiana and less to Scots pine. There is increasing evidence that some fungal and bacterial isolates can reduce the growth and pathogenicity of fungal plant pathogens. In this research, infected needles were collected from 30-year-old Crimean pine (P. nigra subsp. pallasiana) in four locations in Southern Ukraine. In total, 244 of endophytic fungi were recovered from needles of Crimean pine during summer sampling of the host’s microbiome in Ukraine in 2012-2014. Dothistroma spp. were detected using fungal isolation and species-specific priming PCR techniques. Among all endophytes, eight fungal species were selected based on the commonness of their occurrence in the foliage of the host and their antagonistic activity. All selected species were tested for their antifungal activity against Dothistroma needle blight. Good antifungal activity against Dothistroma pini was achieved with the Trichoderma sp. and Gliocladium rosea, indicating their good potential possibility in preventing the Dothistroma needle blight on young pines. Moreover, the significant reduction in numbers of conidia and spore germination was found on needles treated with Trichoderma sp. and Gliocladium rosea, compared to conidia numbers following treatment with other fungi. Thus, the use of an effective biological control agent against Dothistroma could be of value in forest nurseries, where it is essential to reduce losses to D. pini infection prior to transferring pines to field sites for planting out.

Pine needle blight, caused by Dothistroma septosporum (Dorog.) M. Morelet, is one of the most serious foliar diseases of Pinus spp. in Australia and New Zealand. In 16 Pinus radiata (D.Don.) progeny trials in northeastern Victoria, Australia, Dothistroma-caused defoliation varied widely among trials and assessment years, ranging from 5% to 65%. The estimated narrow sense heritability ranged from nonsignificant to as high as 0.69 with a median of 0.36. Spatial autocorrelation of residuals accounted for a significant proportion of residual variance, and that increased heritability estimates. Genetic correlation between defoliation scores at an early age and growth at a later age was negative with a median value of –0.39. Phenotypic correlation between defoliation and survival was low and negative with a median value of –0.11. Economic analyses indicated that at sites with a high risk of infection, the effect of reducing defoliation on profitability was comparable with that of increasing growth at sites free from infection. The genetic parameters and economic impacts of Dothistroma were used to derive selection indices and include resistance to defoliation into the current breeding objective for radiata pine.

Dothistroma septosporum and D. pini are the two causal agents of Dothistroma needle blight of Pinus spp. in natural forests and plantations. Degenerate primers amplified portions of mating type genes (MAT1-1-1 and MAT1-2) and chromosome walking was applied to obtain the full-length genes in both species. The mating-type-specific primers designed in this study could distinguish between the morphologically similar D. pini and D. septosporum and between the different mating types of these species. Screening of isolates from global collections of D. septosporum showed that only MAT2 isolates are present in Australian and New Zealand collections, where only the asexual form of the fungus has been found. In contrast, both mating types of D. septosporum were present in collections from Canada and Europe, where the sexual state is known. Intriguingly, collections from South Africa and the United Kingdom, where the sexual state of the fungus is unknown, included both mating types. In D. pini, for which no teleomorph is known, both mating types were present in collections from the United States. These results provided new insights into the biology and global distribution of two of the world's most important pine pathogens and should facilitate management of the diseases caused by these fungi.

The comparative ease and speed of international trade and travel have enabled or enhanced the spread of pests around the globe. For example, trade in ornamental plants has bolstered the spread of alien Oomycetes such as pathogenic species of Phytophthora. To date, four Phytophthora species have been identified in Finland: P. cactorum on Fragaria x ananassa, Betula pendula and Rhododendron spp., P. plurivora on Rhododendron spp. and Syringa vulgaris, and P. pini and P. ramorum on Rhododendron spp. The ascomycete Colletotrichum acutatum, which was listed as a quarantine pathogen by the European Union until 2009, was introduced in 2000 and can survive in plant debris over two winters in Finland. Positive PCR results have also been obtained from bait plants grown in soil collected from locations where diseased Fragaria x ananassa plants had earlier been destroyed. In the mid-1990s, there was an epidemic of foliar rust caused by the Asian basidiomycete Melampsoridium hiratsukanum on Alnus glutinosa and A. incana. Recently, two ascomycetes that have been introduced are Dothistroma septosporum (responsible for red band needle blight on Pinus sylvestris) and Chalara fraxinea (causing ash decline on Fraxinus excelsior).;

Dothistroma needle blight (DNB), also known as red band needle blight, is an important fungal disease of Pinus spp. that occurs worldwide. On the basis of molecular and morphological studies of the anamorphic stage, Barnes et al. (1) showed that two closely related species were involved in DNB: Dothistroma septosporum (Dorog.) Morelet and D. pini Hulbary. D. septosporum (teleomorph: Mycosphaerella pini Rostr.) has a worldwide distribution and is reported as the species that caused past epidemics of DNB. This species is reported on more than 80 different pine species, and Pinus radiata D. Don (Monterey pine) is classified as a highly or moderately susceptible species, depending on the published sources (4). D. pini (telemorph: unknown) was initially found on needles of P. nigra J. F. Arnold collected from 1964 to 2001 in the north central United States (Minnesota, Nebraska, and Michigan). It was subsequently found in Ukraine and southwestern Russia, where it has been associated with the emergence of DNB on P. nigra subsp. pallasiana (Lamb.) Holmboe, in Hungary on P. nigra, and in Russia on P. mugo Turra (1). In France, D. pini was reported for the first time on P. nigra, and was sometimes found in association with D. septosporum on the same needles (3). Later on, a more intensive survey of DNB was launched in France and 216 stands of Pinus sp. were studied. D. septosporum and D. pini were detected in 133 and 123 stands, respectively. Both species co-occurred in 40 stands but D. pini was only found on P. nigra (subsp. laricio and austriaca) (2). Up to now, D. pini was therefore only reported on European pine species, mainly on the different allopatric subspecies belonging to the black pine complex and on one occasion on P. mugo, which belongs to the same section and subsection as P. nigra. In March 2011, typical symptoms of DNB (needles with orangey-red brown distal ends, dark red bands, and green bases; small and black fruit bodies within the bands) were observed in a 50- to 60-year old P. radiata stand of ~3 ha located in Pyrénées Atlantiques close to the Spanish border (1°36′08″ W, 43°19′51″ N). The density of pine was relatively low and patches of natural regeneration were present. Although nearly all of the trees showed DNB symptoms, less than 50% of their needles were affected by the disease. In this stand, needles showing typical DNB symptoms were randomly taken from four pines and mixed together to form a single sample for analysis. Total DNA was extracted from symptomatic needle pieces. The presence of D. pini was confirmed by a specific multiplex real-time PCR analysis using the D. pini-specific primers/probe combination DPtef-F1-/R1/-P1 (3), and by sequencing a D. pini-specific amplicon generated by another conventional PCR (3) using DPtef-F/DPtef-R primers (GenBank Accession KC853059) (3). D. septosporum was not detected in the sample. To our knowledge, this is the first report worldwide of D. pini on P. radiata, a pine species largely planted in Spain and in the Southern Hemisphere. This is also the first report of this pathogen on a non-European pine species. The original native range and the host range of D. pini remain unknown and there is currently no data about host preferences or aggressiveness on different pine species. References: (1) I. Barnes et al. For. Pathol. 41:361, 2011. (2) B. Fabre et al. Phytopathology 102:47, 2012. (3) R. Ioos et al. Phytopathology 100:105, 2010. (4) M. Watt et al. For. Ecol. Manage. 257:1505, 2009.

During 2010 and 2011, Dothistroma needle blight (DNB), also known as red band needle blight, was observed for the first time in Cass and Pembina counties in North Dakota (ND). In Pembina Co., DNB was observed in two sites in the Jay V. Wessels Wildlife Management Area (JWWMA). In September 2009, yellow spots on green needles were observed on some trees along the western edge of one planting. By June 2010, DNB was found on third- and fourth-year needles in both JWWMA plantings. Symptoms had developed into dark brown bands or spots on necrotic needles that contained erumpent black acervuli. In June 2011, similar DNB symptoms were observed on Pinus nigra, P. flexilis, P. ponderosa, P. cembra, and P. albicaulis in the Dale E. Herman Research Arboretum, Cass Co., ND. DNB was collected in July 2011 in Brookings Co., South Dakota (SD), from a seed source provenance planting of P. ponderosa. To identify the species causing the infections, symptomatic needles were collected in 2010 from both sites in JWWMA and then again from all four locations in 2011 on all pine species infected. Needles of P. nigra from a private residence near Fairland in Shelby County, Indiana (IN), were also included in the sample set. The rDNA-ITS was PCR-amplified either directly from conidia obtained from acervuli on the needles or from cultures obtained from isolations. Amplicons were sequenced and a BLAST search was performed in GenBank. The sequences of samples obtained from P. nigra, P. flexilis, P. cembra, and P. albicaulis in ND, P. ponderosa in SD, and P. nigra from IN showed 100% sequence homology with Dothistroma pini (Accession No. AY808302). These isolates were identical to all previously assayed isolates of D. pini from Nebraska, Minnesota, and Michigan in the United States. The P. ponderosa isolates from all three sites in ND differed from the other isolates and contained a 1-bp point mutation from a C to a T at site 72 (sequence deposited in GenBank, accession KJ933441). Mating type was determined using species-specific mating type primers for D. pini (3). All 26 samples from ND and SD were of the MAT-1 idiomorph, while the sample from IN contained the MAT-2 idiomorph. All cultures are maintained at FABI, University of Pretoria, South Africa. The two species that cause DNB, D. septosporum (G. Dorog.) M. Morelet and D. pini Hulbary, are morphologically indistinguishable and molecular characterization remains essential for correct species identification (1). Host and geographical distribution range determinations of Dothistroma spp. made without molecular methods are not valid. To date, species confirmed using DNA sequences in the United States include D. septosporum in the Pacific Northwest states of Oregon and Idaho on P. ponderosa, in Montana on P. contorta v. latifolia, and D. pini in the North Central states of Nebraska, Minnesota, and Michigan on P. nigra (1). This study documents the presence of D. pini in three additional states, including a first report of DNB in ND and SD. It also includes new records of D. pini infecting P. flexilis, P. cembra, P. albicaulis, and P. ponderosa. Results of this study have expanded the documented host range of D. pini in the United States from one (P. nigra) to five species. Globally, D. pini is now known to infect a total of 10 pine hosts (2,4,5). References: (1) I. Barnes et al. Stud. Mycol. 50:551, 2004. (2) I. Barnes et al. For. Pathol. 41:361, 2011. (3) M. Groenewald et al. Phytopathology 97:825, 2007. (4) D. Piou et al. Plant Dis. 98:841, 2014. (5) B. Piskur et al. For. Pathol. 43:518, 2013.

The mitosporic ascomycetes Dothistroma septosporum s.s. (Dorog.) Morelet and D. pini Hulbary are closely related species (1) causing red band needle blight on Pinus spp. D. septosporum (teleomorph Mycosphaerella pini Rostr.) is considered as a cosmopolitan species, whereas D. pini (no teleomorph known) seems to have a more restricted distribution area. Detected in the United States on Pinus nigra for the first time, it was later found in Russia, Ukraine, Hungary, and France on different pine species (P. radiata, P. mugo, P. pallasiana) (3). In Switzerland, Dothistroma sp. (species not further determined) was recorded in 1989 for the first time and since then only damages on planted pines (mainly P. mugo and P. nigra) in urban areas were reported (R. Engesser, personal communication). In September 2012 and in April 2013, several planted mature trees and naturally regenerated young trees of P. nigra with Dothistroma needle blight were detected on a climatically mild forest site on limestone at the shore of Lake Walensee (47°07′48.0″ N, 9°13′54.4″ E, 420 m asl). In 2012, symptomatic needles were collected from the litter under one planted mature P. nigra tree and in 2013, symptomatic needles were collected from green twigs from a 2 m tall naturally regenerated P. nigra specimen. Conidiomata were frequently observed in the red bands but no conidia were detected. For fungal isolation, the surface of infected needles was shortly disinfected with 95% ethanol. The epi- and hypo-dermis covering the still closed conidiomata was removed and small tissue samples from the mesophyll (less than 0.5 mm length) were placed on malt extract agar (15 g/liter agar, 20 g/liter malt extract) amended by 50 mg/liter oxytetracycline. Conidia were observed after one year at 4°C in the resulting pure colonies (3 to 4 cm diameter on malt extract agar medium). The conidia formed by strain OH_120923_2_1_1 (KJ878557 = D. pini) were hyaline, smooth, thin-walled, 2- to 4-celled, and 31.6 (22 to 37) × 2.8 (2 to 3.5) μm. While conidial morphology of both Dothistroma species overlap, DNA was extracted and the internal transcribed spacer (ITS) region (primers ITS 1 and ITS 4) sequenced (KJ878557 to 81). From the 25 obtained ITS sequences, seven were identical with AY808275 (D. septosporum from P. radiata, South Africa, CMW 684), three were identical with AY808302 (D. pini from P. nigra, Michigan, CMW 10951), and 15 were identical with DQ926964 (D. pini from P. pallasiana, Ukraine, CMW 23767). The North American and Ukrainian D. pini sequences (AY808302 and DQ926964) showed only 1 bp difference. In addition, mating type genes were amplified using the method described by Groenewald et al. (2) for D. pini and scored using gel electrophoresis. Analyses showed that both D. pini ITS-sequence variants (e.g., KJ878557 and KJ878558) and both mating types were sometimes present in the same needle. In two cases, both mating types and ITS-sequence variants were also present within the same lesion. Interestingly, D. pini and D. septosporum were found on the same tree but not on the same needles. This is the first report of D. pini in Switzerland. Although symptoms of red band needle blight (species not determined) were repeatedly observed on this site during the last 20 years, the disease level always remained low and no tree mortality was noted. However, due to the presence of two ITS-sequence variants and both mating types, the incidence of D. pini in Switzerland deserves attention. References: (1) I. Barnes et al. Stud. Mycol. 50:551, 2004. (2) M. Groenewald et al. Phytopathology 97:825, 2007. (3) D. Piou and R. Ioos. Plant Dis. 98:841, 2014.

The aim of this thesis was to optimize and improving reliable, fast, sensitive and specific field-deployable tools for the early detection of quarantine plant pathogens. In the first part of the thesis the work was concentrated in developing a field-applicable LAMP-based assay for the detection of Xylella fastidiosa, Phytophthora ramorum and Ceratocystis platani. Each assay, optimized on the portable instrument Genie II ® (Optigene, UK), was based on the conventional LAMP reaction and showed the capability to detect X. fastidiosa, C. platani and P. ramorum with high specificity and sensitivity in only 30 minutes also on plant samples for which a rapid kit method for in field-DNA extraction was also utilized. However, the assay targeting C. platani and P. ramorum were able to detect also C. fimbriata and P. lateralis, having also many cross reactions with other Phythophtora species. Even if the specificity was assessed by results obtained from melting analyses, that gave different temperature between target and non-target species, improving the specificity of a LAMP assay was needed. The second part of the thesis was hence concentrated in improving the chemistry and the specificity of a LAMP assay. The use of sequence-specific LAMP probes was analyzed by the development of a conventional and FRET-assimilating probe-based LAMP method targeting Fusarium circinatum, a pine pathogen for which specificity is a very important requirement concerning diagnostics. The capability of increasing the specificity using this novel LAMP chemistry was assessed by comparing LAMP results of conventional and probe-based LAMP reaction developed for F. circinatum: with conventional reaction many cross reactions were obtained with phylogenetically closest Fusaria while with the probe-based method only F. temperatum was amplified as cross reaction. Due to positive results obtained applying the probe-based method on wood samples DNA extracted with the field method the suitability for using it into the field was also assessed. The same probe-based LAMP chemistry was then implemented for multiplex application concerning pine needles pathogens Dothistroma septosporum, Dothistroma pini and Lecanosticta acicola, obtaining as preliminary results that of having a multiplex specific reaction directly in the field in about 10 minutes. Concerning this third part of this work, the possibility to apply the described method on crude samples was investigated concerning pine needles for which preliminary test to optimize a field suitable crude extraction method were carried out with promising results. As in the last part of this work was assessed that in Italy the distribution of Dothistroma septosporum is widespread by applying a TaqMan-based qPCR method while L. acicola was reported only in restricted places and D. pini was never reported, the developed LAMP method could be useful to prevent and monitoring their spread and introduction.