Saaresurma (Hymenoscyphus fraxineus) otsingud saare liikide (Fraxinus spp.) herbaareksemplaridelt
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Kuupäev
2015
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Autorid
Ajakirja pealkiri
Ajakirja ISSN
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Kirjastaja
Abstrakt
Saare perekonna puhul on tegemist õlipuuliste sugukonda kuuluvate heitlehiste
puuliikidega. Perekonda Fraxinus spp., kuulub hinnanguliselt 70 erinevat saareliiki.
Saaresurm on suhteliselt hiljuti, 1990-ndatel aastatel avastatud taimepatogeen, mille
tekitaja on kottseen Hymenoschyphus fraxineus (anamorf Chalara fraxinea). Tegemist on
hetkel ühe tõsisema metsapatoloogilise probleemiga Euroopas. Nakatab igas vanuses
harilikku saart aga ka teisi saareliike: F. nigra, F. pennsylvanica, F. americana, F.
mandshurica, F. sogdiana, F. angustifolia, F. chinensis, F. ornus.
Antud magistritöö eesmärgiks on uurida seda, 1) kas H. fraxineus võis varjatud kujul
olemas olla juba varasemal ajal kui see on hetkel teada ning 2) kas saaresurma
haigustekitaja esineb väliselt tervete puude seemnetel või ainult haigustunnustega
saarepuude seemnetel. Töö ülesandeks on läbi viia seemnete ja erinevatelt
herbaareksemplaridelt kogutud proovide analüüs, et välja selgitada võimalik saaresurma
tekitaja olemasolu nimetatud proovidel kasutades vastavaid liigispetsiifilisi DNA
praimereid.
Seemnete DNA analüüsi tulemused näitasid seda, et H. fraxineus’e liigispetsiifilise
praimeriga tehtud testide tulemusena osutusid positiivseks kolmelt puult korjatud seemnete
proovid, mis moodustasid korjatud seemnepuude koguhulgast ca 14 %. Nende hulgas oli
nii väliste haigustunnustega, aga ka ilma väliste haigustunnusteta puude seemneid. Sellest
järeldub, et H. fraxineus nakatab nii väliselt tervete puude kui ka väliste haigustunnustega
puude seemneid. Samuti näitavad tulemused seda, et saaresurma tekitaja on meie looduses
seal kus on saare puid. Seega, nakatunud alalt võib haiguse tekitaja levitada suurte
vahemaade taha ka seemnete transpordiga.
Herbaareksemplaride proovidest osutusid saaresurmaga nakatunuks üheksa proovi 119-
nest ning proovid analüüsiti molekulaarselt H. fraxineuse liigispetsiifiliste praimeritega.
Kaheksa positiivset proovi pärinesid ajavahemikust 1959-1976. Üllatuslikult üks
analüüsitud proov pärines oluliselt varasemast ajast.
Vanim Eestist pärinev positiivne proov on aastast 1959 Saaremaalt. Saaremaale ja mujale
Eestisse võis H. fraxineus sattuda 1952-1953. aastal saare istutusmaterjali kaasabil.
Saadud tulemused aitavad meil paremini mõista seenpatogeeni ajalugu, selle kulgu ja seda
kuidas saaresurm võis varasemalt saari mõjutada. Samuti näitavad tulemused seda, et
haigus esines Euroopas juba tunduvalt varasemal ajaperioodil kui seni arvatud.
Fraxinus spp.is a family of wooden plants that contains about 70 species of medium to large trees. Ash dieback (Hymenoscyphus fraxineus) and its anamorph Chalara fraxinea is a relatively recently, during the 1990-s, discovered forest pathogen. It’s known as one of the most serious forest pathology problems in Europe at the moment. The pathogen infects ashes at all ages. H. fraxineus was detected on the ashes as follows: F. excelsior, F. nigra, F. pennsylvanica, F. americana, F. mandshurica, F. sogdiana F. angustifolia, F. chinensis, F. ornus. The objective of the thesis is 1) to find out whether H. fraxineus may have been present earlier on the Fraxinus spp. than is now known and 2) to search H. fraxineus on seeds of visually healthy and unhealthy hosts. The purpose of the thesis is to carry out samples to DNA analysis, which was taken from the herbarium specimens and seeds from different Fraxinus species using the speciesspecific primers of H. fraxineus. The DNA analysis carried out with samples taken from seeds showed that ca. 14 % of the seeds were infected with the pathogen. That included seeds, which were collected from healthy and unhealthy ashes. It shows that disease is everywhere with ashes and the disease agent can travel to long distances with seeds. DNA analysis carried out with samples from herbaria specimens, which showed that 9 samples were infected by H. fraxineus from all 119 samples. Eight of the infected samples were found from a time period 1959-1976 in Estonia. One of the oldest samples was infected by the disease agent even longer time ago. The oldest infected sample gathered from Estonia dates to a year 1959. It is plausible that the disease was introduced to Estonia with seedlings which were planted to Luua and other locations in Estonia during 1952-1953. The results of this thesis help us to understand the history and behaviour of this pathogen a bit better as it is known now.
Fraxinus spp.is a family of wooden plants that contains about 70 species of medium to large trees. Ash dieback (Hymenoscyphus fraxineus) and its anamorph Chalara fraxinea is a relatively recently, during the 1990-s, discovered forest pathogen. It’s known as one of the most serious forest pathology problems in Europe at the moment. The pathogen infects ashes at all ages. H. fraxineus was detected on the ashes as follows: F. excelsior, F. nigra, F. pennsylvanica, F. americana, F. mandshurica, F. sogdiana F. angustifolia, F. chinensis, F. ornus. The objective of the thesis is 1) to find out whether H. fraxineus may have been present earlier on the Fraxinus spp. than is now known and 2) to search H. fraxineus on seeds of visually healthy and unhealthy hosts. The purpose of the thesis is to carry out samples to DNA analysis, which was taken from the herbarium specimens and seeds from different Fraxinus species using the speciesspecific primers of H. fraxineus. The DNA analysis carried out with samples taken from seeds showed that ca. 14 % of the seeds were infected with the pathogen. That included seeds, which were collected from healthy and unhealthy ashes. It shows that disease is everywhere with ashes and the disease agent can travel to long distances with seeds. DNA analysis carried out with samples from herbaria specimens, which showed that 9 samples were infected by H. fraxineus from all 119 samples. Eight of the infected samples were found from a time period 1959-1976 in Estonia. One of the oldest samples was infected by the disease agent even longer time ago. The oldest infected sample gathered from Estonia dates to a year 1959. It is plausible that the disease was introduced to Estonia with seedlings which were planted to Luua and other locations in Estonia during 1952-1953. The results of this thesis help us to understand the history and behaviour of this pathogen a bit better as it is known now.
Kirjeldus
Märksõnad
saar (bot.), herbaareksemplarid, magistritööd