Population structure of causal agents of red band needle blight and brown spot needle blight of pines in selected areas of Central and Southeastern Europe

Sadiković, Dušan (author), Jurc, Dušan (mentor), Piškur, Barbara (comentor)

Dothistroma needle blight (DNB), caused by Dothistroma septosporum and D. pini, and Brown spot needle blight, (BSNB), caused by Lecanosticta acicola, belong to the most harmful and important pine diseases today. DNB has been present in Southeastern Europe since the 1950s and BSNB since the 1970s. Recent outbreaks of BSNB and the fact that DNB is widely spread, made it necessary to study the population structure of these disease agents by measuring their genetic variety in phylogenetic, mating type gene and microsatellite marker analyses. In addition, the diversity of certain morphological traits was determined and migration patterns evaluated through use of coalescent-based method. Populations from Slovenia, Serbia and Croatia, obtained from Pinus nigra, P. mugo and P. halepensis, were selected for the study and compared with populations from Europe (EU), North America (NA), Central America (CA), South America (SA), Africa (AF) and Australia (AU). Serbian and most of Slovenian D. septosporum isolates grouped in phylogenetic analyses based on elongation factor (EF1-α) and β-tubulin-2 (βT2) together with the isolates from EU and NA, while Celje (Slovenia) formed a so far unrecognized new EF1-α haplotype. Croatian D. septosporum isolates also formed a new EF1-α haplotype and a separate clade, while they grouped with isolates from NA, CA, SA, AU and AF in the βT2 gene region analysis. ITS analysis was uninformative. In population structure analyses, most of Slovenian and Serbian populations composed a single genetic cluster, while populations from Trenta (Slovenia) and Kožino (Croatia) formed separate clusters. Migration analyses showed that gene flow occurs between populations from Slovenia and Serbia. Slovenian D. pini isolates and isolates from SA have identical ITS, EF1-α in βT2 sequences. In population structure analyses, D. pini isolates displayed clonality and low genetic diversity, likely as a consequence of a single event introduction. L. acicola phylogenetic analysis revealed a novel EF1-α haplotype in Croatian population and showed that Slovenian and Croatian isolates share a common ancestry with individuals from Central and Northern Europe. Population structure analysis revealed four distinct genetic clusters, generally corresponding to their respective geographic location and hosts. Observed unequal ratio of mating types and low overall genetic diversity in the population indicates that L. acicola predominantly reproduces asexually. Low genetic variation within each of the four clusters and absence of or low gene flow suggests that the different L. acicola populations were independently introduced.

• Language: Slovenian
• Keywords: Dothistroma septosporum, D. pini, Lecanosticta acicola, Pinus, population structure, phylogeny, mode of reproduction
• Work type: Doctoral dissertation
• Typology: 2.08 - Doctoral Dissertation
• Organization: BF - Biotechnical Faculty
• Publisher: [D. Sadiković]
• Year: 2020
• PID: 20.500.12556/RUL-121951
• UDC: 630*17:630*18(4)(043.3)=111
• COBISS.SI-ID: 37302275
• Publication date in RUL: 12.11.2020

Secondary language

• Language: English
• Title: Populacijska struktura gliv povzročiteljic rdeče in rjave pegavosti borovih iglic na izbranih območjih srednje in jugovzhodne Evrope

Abstract

Rdeča pegavost borovih iglic, ki jo povzročata glivi Dothistroma septosporum in D. pini ter rjava pegavost borovih iglic, ki jo povzroča gliva Lecanosticta acicola, sta dve izmed pomembnejših bolezni borov. Rdeča pegavost borovih iglic je v jugovzhodni Evropi prisotna od leta 1950, rjava pegavost od leta 1970, obe bolezni se v zadnjih letih razširjata po Evropi in širše. Na osnovi filogenetskih analiz treh genskih regij, analize mikrosatelitnih markerjev, ugotavljanja načina razmnoževanja ter na osnovi izbranih morfoloških lastnosti smo ugotavljali strukturo populacij, genetsko raznolikost ter vzorce migracij populacij D. septosporum, D. pini in L. acicola. Izbrane populacije iz Slovenije, Srbije in Hrvaške, pridobljene iz Pinus nigra, P. mugo in P. halepensis, so bile primerjane s izolati iz Evrope (EU), Severne Amerike (SA), Centralne Amerike (CA), Južne Amerike (JA), Afrike (AF) in Avstralije (AU). V filogenetskih analizah elongacijskega faktorja 1-α (EF1-α) in β-tubulina-2 (βT2) se srbski in večina slovenskih izolatov D. septosporum združujejo z izolatiiz EU in SA, medtem ko izolati D. septosporum iz Celja (Slovenija) predstavljajo doslej neznani EF1-α haplotip. Hrvaški izolati D. septosporum so ravno tako predstavljali novi haplotip EF1-α in ločeno skupino, so se pa v analizi genske regij βT2 združili z izolati iz SA, CA, JA, AU in AF. ITS analiza je bila neinformativna. Populacijske in migracijske analize so pokazale, da se večina preučevanih slovenskih in srbskih D. septosporum populacij uvršča v isto genetsko gručo, medtem ko se populacije iz Trente (Slovenija) in Kožina (Hrvaška) grupirajo posebej. Slovenski D. pini izolati in izolati iz SA so imeli enake ITS, EF1-α in βT2 sekvence. V populacijskih analizah so vsi izolati D. pini pokazali klonalnost, nizko genetsko pestrost, kar nakazuje na vnos iz enega vira. Hrvaška populacija glive L. acicola vsebuje EF1-α haplotip, ki ni opisan v drugih populacijah L. acicola. Filogenetska analiza na osnovi regije EF1-α pokaže, da imajo izolati L. acicola iz Slovenije in Hrvaške skupne prednike z izolati iz srednje in severne Evrope. Analiza populacijske strukture slovenskih in hrvaških populacij L. acicola je razkrila štiri različne genetske gruče, ki praviloma odražajo geografsko lokacijo in gostitelje. Opaženo neenakomerno razmerje tipov parjenja, nizko število haplotipov in nizka splošna genetska raznolikost v populaciji nakazujejo na močan vpliv nespolnega razmnoževanja. Nizka genetska variabilnost znotraj vsakega od štirih grozdov in odsotnost oziroma nizek genski pretok nakazujeta na to, da so različne L. acicola populacije bile vnesene neodvisno.

• Keywords: Dothistroma septosporum, D. pini, Lecanosticta acicola, Pinus, populacijska struktura, filogenija, načini razmnoževanja