Search

Dothistroma needle blight ( DNB) is one of the most devastating needle diseases on Pinus spp. worldwide. Ever since the description of the causal agent of the disease in Europe in 1911 as Cytosporina septospora, and independently in the USA in 1941 as Dothistroma pini, there has been considerable taxonomic discordance regarding the name of the pathogen used in literature. This was compounded both by the proposal of different varieties of the pathogen based on differences in spore size and the application of dual nomenclature where three names, Scirrhia pini, Eruptio pini and Mycosphaerella pini, were used to describe the sexual morph of the fungus. More recent studies using sequence-based methods revealed that DNB can be caused by either one of two distinct species, that is D. septosporum and D. pini. These important species have not been adequately typified, and this perpetuates lack of stability for their names. In this study, these names are fixed to reference sequences linked to living cultures representing type specimens. To achieve this goal, we designate an epitype for D. pini and a neotype for D. septosporum. The known polymorphism in the ITS region, the barcoding gene for these fungi, is characterized and a complete taxonomic history is provided for the genus Dothistroma. [ABSTRACT FROM AUTHOR]

Dothistroma needle blight ( DNB), caused by Dothistroma septosporum and Dothistroma pini, is a highly damaging disease of pine. DNB was originally considered a problem on exotic Pinus radiata plantations in the Southern Hemisphere and on both exotic and native pines in parts of North America in the 1960s. Since the mid-1990s, however, DNB has increased in importance in various parts of the world, including Europe. On susceptible species, DNB causes premature needle drop, a loss of yield and, in some circumstances, mortality. In some areas, DNB is controlled by the application of copper-based fungicides and silvicultural techniques, such as thinning and pruning. In New Zealand, there has also been a long history of selection of more resistant P. radiata for use in breeding programmes. A richer understanding of the resistance mechanisms involved in the Dothistroma-Pinus interaction will play a critical role in helping the development of sustainable integrated DNB management strategies. This review therefore summarizes current knowledge of defence mechanisms involved in the defence of Pinaceae against needle and shoot pathogens and identifies research gaps. Collaborative research efforts from countries directly or indirectly affected by DNB are rapidly generating new knowledge to address these gaps. [ABSTRACT FROM AUTHOR]

Dothistroma needle blight of Pinus spp. is a serious disease that can be caused by two distinct fungal species: Dothistroma septosporum and D. pini. Dothistroma septosporum has a broad pine host range, a worldwide distribution and has caused many serious epidemics. In contrast, D. pini has a more limited distribution; known only from Europe and the USA. Unlike the situation for the better-known D. septosporum, the population biology of D. pini has not been intensively studied. Microsatellite markers developed for D. septosporum either do not amplify in D. pini or they are uninformative. The aim of this study was to develop a robust set of microsatellite markers that amplify across different D. pini isolates from a range of geographical locations and different host species. The genome of an isolate from Ukraine was sequenced using Mi-Seq Illumina sequencing. Thirty-two primer pairs were designed to amplify microsatellite regions targeting a mixture of di-, tri-, tetra-, penta- and hexa- nucleotide repeat regions. The results yielded 16 polymorphic markers that amplified across 32 isolates from seven countries and four hosts. Screening of the polymorphic markers on a population of D. pini from France and Slovenia revealed that the Slovenian isolates were clonal but that those from France were genetically more diverse. The markers developed in this study will provide a useful tool with which to study the population structure and genetic diversity of D. pini populations in countries where it is emerging as an important pathogen. [ABSTRACT FROM AUTHOR]

Summary Dothistroma septosporum and D. pini cause the serious pine needle disease, Dothistroma needle blight (DNB). Of these, D. septosporum has a global distribution, while D. pini is known only from the USA, Russia, Ukraine and France. During a study of D. septosporum isolates from Pinus nigra in Hungary, microsatellite markers revealed the presence of a second Dothistroma species. The aim of this study was to identify the DNB pathogens occurring in Hungary using four different molecular techniques. These included sequencing of the rDNA ITS region, a species-specific ITS-RFLP, mating type primers and a diagnostic microsatellite marker, Doth_A. Results showed that both D. septosporum and D. pini occur in Hungary and that both DNB pathogens were present on the same trees and in some cases, the same needles. Mating types MAT1 and MAT2 of D. septosporum were shown to be present in Hungary, but only the MAT2 of D. pini was found. In addition, examination of needles with DNB symptoms from Russia revealed the presence of D. pini on Pinus pallasiana and P. nigra as well as on a new host, Pinus mugo. The molecular markers applied in this study were sufficiently robust to identify and differentiate between the two DNB pathogens, both in culture and directly from needles. They will consequently be useful to document the geographical range and to monitor the spread of D. septosporum and D. pini in future studies. [ABSTRACT FROM AUTHOR]