3. Doktoritööd
Selle kollektsiooni püsiv URIhttp://hdl.handle.net/10492/7081
Sirvi
Sirvi 3. Doktoritööd Autor "Drenkhan, Rein" järgi
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Kirje Distribution and population genetic analysis of the agents of invasive needle and shoot diseases of conifers in Northern Europe(Eesti Maaülikool, 2017) Adamson, Kalev; Drenkhan, Rein; Capretti, Paolo (opponent)Generally, invasive pathogens settle first exotic host species and later the native ones. Invasive conifer pathogens Lecanosticta acicola and Diplodia sapinea were first documented in northern Europe on exotic hosts and later on native ones. Still, L. acicola has not been found on the native Scots pine. Abies species for the known as pine pathogen Dothistroma septosporum and Pinus mugo var. pumilio for L. acicola were documented as the new hosts for them. Quarantine pest L. acicola is thought to spread into and inside Estonia via anthropogenic activity. It was proved by the mating type analyses, as only MAT1-1 was firstly found and several years later MAT1-2 was detected. It predicts increasing virulence of the pathogen. Similarly has spread D. sapinea, the pathogen was documented first time on Austrian pine in one location and after that on Scots pine individuals in 2012 in Vormsi Island. At the same time the pathogen was naturally distributing from South to North as a clear front and has reached the northernmost front up to the central Estonia by 2014. Investigations demonstrated that exotic host species are more sensitive to alien pathogens than are native ones. Several analysed genetic characteristics of D. septosporum populations in northern Europe, in Russian Far East (eastern Asia) and Bhutan (south central Asia) revealed that the fungus is not alien in northern Europe, but may be native to Baltic countries, Finland and western Russia. This result confutes the hypotheses that D. septosporum could spread to northern Europe from eastern populations. Asian D. septosporum populations were not similar to the northern European ones, but the clustering analyses showed some similar genetic pattern in populations of the Russian Far East and west coast of Norway. Other analysed populations in northern Europe were quite similar. The annual forest survey (including molecular survey) discovers and provides valuable information about new invasive forest pathogens, their disease severity and host range. It is essential for assessment of current situation in forests and helps to outline quicker and effective protection measures. At the same time the thesis provides information to quarantine regulation authorities by early detecting the pathogens and evaluating their spread in our environment. We recommend to deal with the imported seedlings and seeds with special care, while they may carry new pathogens or new genes of the already known ones.Kirje Distribution of and damages by Dutch elm disease agents in Northeastern Europe(Eesti Maaülikool, 2021) Jürisoo, Liina; Drenkhan, Rein; La Porta, Nicola (opponent)As elsewhere in the world, elms in Northeastern Europe are threatened by Dutch elm disease (DED), which is one of the most devastating diseases of the elms. The aim of the doctoral thesis was to investigate the spread of Dutch elm disease, its agents and their impact on the health status of different elms, vectors and the health of the elms in different habitats in Estonia and North-West Russia. The results of the work demonstrated that U. glabra is more susceptible to DED than U. laevis and elm hybrids. Therefore, we recommend to use U. laevis rather than U. glabra in landscaping. Elm hybrids may be promising in green areas, but they still need to be tested before they can be widely used in the conditions of Northeastern Europe. DED is known to have caused damage to Estonia's elms since 1930s. First, the pathogen was Ophiostoma ulmi which has now been replaced by a new species, Ophiostoma novo-ulmi. In Europe the European subspecies (subsp. novo-ulmi) and to a lesser extent the North American subspecies (subsp. americana) are both the causal agents of DED in Estonia; however, the latter was detected only in Northwestern Estonia, incl. Hiiumaa island. As the American subspecies of DED is more aggressive than the European one, it causes the mortality of elms at a faster rate as was the case in North Estonia. In the current work the presence of an aggressive hybrid of this pathogen was also proved for the first time in Estonia in 2020. At the same time, our investigations demonstrated that the pathogen´s hybrids between subspecies are even more aggressive as revealed by their significantly faster growth in pure cultures. The reason may be the poor health status of elms in Russia where these hybrids were particularly often detected. Additionally, in this work it was found that Xyleborinus saxesenii and Xyleborus dispar are new potential vectors for DED. This is clear evidence of wider spread potential of DED and greater risk to elms.Kirje Epidemiological Investigation of Pine Foliage Diseases by the Use of the Needle Trace Method(Eesti Maaülikool, 2011) Drenkhan, Rein; Hanso, MärtOkkajäljemeetodi kasutamisest männi okkahaiguste epidemioloogilises uurimistöös Dendrokronoloogia meetodeid edasiarendav okkajälje meetod (NTM) avastati ja arendati välja Soome metsateadlaste-patoloogide poolt 1980.-ndate lõpus. NTM unikaalsus seisneb võimaluses konstrueerida retrospektiivseid pikaajalisi igihaljaste puude okastikku iseloomustavaid andmeridu, mis võivad ulatuda kaugele minevikku. NTM tekkega sai võimalikuks uurida okaspuude, eelkõige männiliikide okaste pikaajalise dünaamika mustreid ning hinnata seda, milline on olnud näiteks okaste eluiga läbi aegade, millist okastiku hulka ja seisundit võib pidada normilähedaseks, jne. Dateerimist võimaldavad retrospektiivsed okastikudünaamika hinnangud on olulised metsade tervise ja kasvu põhjuslike seoste uurimise seisukohalt. Lisaks okaste n-ö normaalsele, vanusest tingitud varisemisele võivad erivanuselistes okkaklassides põhjustada normist varasemat kadu ka mitmed seenpatogeenid, putukkahjurid ja abiootilised tegurid. Seni oli puu kasvuga seostatud kogu rohelist okastikku, st et okkad nende vanusele vaatamata seonduvad otse ja positiivselt puu jooksva aasta kasvuga. Seni ei olnud piisavalt selgelt käsitletud seda, milline osa hariliku männi (Pinus sylvestris L.) mitmeaastasest okastikust toetab otseselt puu kasvu. Seega polnud ka selge, neist milliste okaste kadu vähendab enam puu kasvu. Kõrvutades NTM andmeridasid näiteks ilmastikutunnuste andmeridadega tekkis esmakordselt võimalus retrospektiivselt välja selgitada oluliste okkahaiguste epideemia-aastad, hinnata nende sagedust ja mõju puude kasvule ning nende abil prognoosida epideemiate esinemist lähiaastatel. Samuti võimaldab NTM määratleda uute saabuvate haiguste ründe eripärasid männile. Arvestades eeltoodut, püstitati käesolevas doktoritöös järgmised küsimused: 1) kas on võimalik, seostades omavahel hariliku männi okastiku- ja juurdekasvu tunnuseid, määratleda nn produktiivne okastik (PO); 2) milline on mändidel üksnes PO-st pärineva okkakao mõju puude kasvule; 3) kuidas toimus Eesti asustamine invasiivsete seenhaiguste poolt ning 4) kas saab PO mõiste abil hinnata uute invasiivsete haiguste ründe eripära mändidele; 5) kas on võimalik NTM abil retrospektiivselt välja selgitada männi 20. sajandil kõige ohtlikuma okkahaiguse, männi-pudetõve tekitaja (Lophodermium seditiosum) epideemiate aegrida, samuti tema mõningaid jätkuvalt puudulikult analüüsitud metsapatoloogilisi ja epideemilisi iseärasusi. Püstitatud eesmärkide täitmiseks analüüsiti töömahuka NTM juhendite kohaselt hariliku männi 123 isendit. Kokku saeti välja ca 2550 pakku-aastavõrset, millistest paljastati pikilõikes ning analüüsiti ca 25 000 aastarõngast, lugedes igalt neist kõik seal nähtavad okkajäljed. Viimaste järgi konstrueeriti perioodi 1887–2006 kohta retrospektiivsed okastiku andmeread, PO määramiseks jagati retrospektiivselt rekonstrueeritud okastik erinevatesse okka-vanusklassidesse. Uute okkahaiguste avastamiseks ja nende levikudünaamika selgitamiseks rajati üle Eesti seirepunktid eksoot- ja hariliku männi kasvukohtadesse, neist koguti regulaarselt haigusproove. Töö olulisimate tulemustena selgus, et noorematest männi okkaklassidest kaks, eelkõige eelmisel ja üle-eelmisel aastal tekkinud okkad „toidavad” männi jooksva aasta juurdekasvu enim. Jooksval aastal sündinud okkad mõjutavad vaid männi radiaalkasvu ja sedagi vaid kasvuaasta teisel poolel. Esmakordselt õnnestus hinnata üksnes produktiivsest okastikust pärineva okkakao mõju mändide kasvule. Selgus, et 50%-line okkakadu ei tähenda juurdekasvu samaväärset vähenemist. Antud töö käigus avastati mändidelt Eestis mitu uut invasiivset seenpatogeeni: Mycosphaerella pini, M. dearnessii ja Diplodia pinea, neist kaks üldse esmakordselt Balti- ja Põhjamaades. Kõik need on mitmetes maades ja mandritel tuntud kui ohtlike okkahaiguste tekitajad, kaks esimest on ka karantiinsed. Töös analüüsitakse Eesti koloniseerimise käiku uute patogeenide poolt. M. dearnessii Eestis on aga seni ainus nimetatud seene dokumenteeritud esinemise koht terves Põhja-Euroopas. M. pini uuringutel avastati, et see liik on Eestis võimeline sporuleerima ja levima tema jaoks ebatavalisel ajal – ka pehmetel talvedel ning et see surmab puudel eelkõige just PO. Krooniline PO kadu, aasta-aastalt, nõrgestab puud peagi elujõuetuseni. Mitmete uute seenpatogeenide saabumine Eestisse 21. sajandil on oluliselt muutnud varasemaid suhteid ja seoseid männiokaste patoloogias. Uued patogeenid demonstreerivad teistsugust ofensiiv-strateegiat võrreldes senise, epideemilise männi-pudetõvega. Viimase epideemiate vaheaastad võimaldavad mändidel taasluua okastiku ja panustada selle abil juurdekasvu ja varuainete ladestumist. Selles seisnebki võrreldavate (uute ja vana) haiguste ofensiiv-strateegiate erinevus. Dokumenteeritud männi-pudetõve epideemiate ja ilmastikuandmete kõrvutamisel leiti esmalt epideemiaid vallandanud ilmastikutingimuste kriteeriumid. Seejärel, NTM meetodil analüüsitud retrospektiivsete okkakadude ja möödaniku ilmastikuandmete baasil saadud kriteeriumide alusel rekonstrueeriti männi-pudetõve epideemia-aastad enam kui terve möödunud sajandi kohta. Uuringutel selgus ka mändide kõrgeim vastuvõtlik iga männi-pudetõve suhtes, see on kuni 24 aastat. Tulemused täpsustavad seniseid teadmisi männi-pudetõve epideemia initsieerimisest ja on aluseks kõnealuse, jätkuvalt ohtliku okkahaiguse prognoosimudeli väljatöötamisele.Kirje Genetic diversity, origin, and new hosts of the invasive pathogen Lecanosticta acicola in northern Europe(Estonian University of Life Sciences, 2022) Vester, Marili; Drenkhan, Rein; Institute of Forestry and Engineering; Müller, Michael M. (opponent)Lecanosticta acicola is an ascomycete causing Brown Spot Needle Blight (BSNB) – a foliar disease affecting pine species (Pinus spp.). The disease causes premature needle shedding which leads to reduced growth of the trees and to severe defoliation which may cause death of the infected trees. The native range of L. acicola is in North America but during the last century anthropogenic activity introduced the pathogen also into Europe and Asia. In Europe, L. acicola was first detected in southern and central regions, but during the current century the disease agent has significantly distributed northward and is now present also in the Baltic states and southern Sweden. So far, in northern Europe, the disease has mostly affected non-native pine species. Nevertheless, by today, L. acicola has already succeeded to infect native Scots pine (Pinus sylvestris), although so far damage on the P. sylvestris is insignificant and only the trees growing in the immediate proximity to non-native P. mugo have been found to be infected. The distribution range of L. acicola appears to be expanding also to the western Asia. In this thesis the pathogen was identified for the first time in Turkey and Georgia. In Turkey, the infection of BSNB was found also on Cedrus libani, proving that L. acicola is not only a Pinus-specific pathogen. Identical genetic strains of the pathogen were found on the distances that the fungus could not spread naturally. Identical strains were found to be shared even between continents, being present in Canada and Germany, but similarly strains were also shared between the countries in Europe. Lecanosticta acicola has reached northern Europe predominantly from pre-existing populations in central Europe and not directly from its native range in America. Surprisingly high diversity found from the populations in northern Europe is probably the result of repeated introductions from genetically different source populations. Although, by today, both mating types of the fungus are present in northern Europe and probably in some limited areas the sexual reproduction takes place, the clonal reproduction mode dominates in this region. Based on the so far distribution of this pathogen and that the ongoing climate changes support its dissemination, it can be assumed that northwards spread of L. acicola will continue in Europe. It is important to avoid any further increase in the diversity of pathogens’ populations, that could easily happen if new fungal strains are imported with insufficiently controlled planting material. An increase in diversity could lead to dangerous development of strains with higher virulence or higher suitability to local climate conditions which could result in higher damage to the forest stands.