Terpene analysis and transcript profiling of the conifer response to Heterobasidion annosum s.l. infection and Hylobius abietis feeding

During their life, conifers are attacked by fungal pathogens and insects. In the European forests, Heterobasidion annosum sensu stricto (s.s.) attacks Scots pine (Pinus sylvestris) roots, whereas Heterobasidion parviporum causes the majority of decay in Norway spruce (Picea abies), both causing severe economic losses. Another significant health problem of Scots pine is caused by Hylobius abietis, the large pine weevil, which damages newly established Scots pine stands. Several defence reactions in trees are activated upon fungal infection and insect attack, but these reactions have not been comprehensively studied in conifers. In this dissertation, the responses of mature Norway spruce and Scots pine trees to Heterobasidion spp. inoculation, and the responses of Scots pine saplings to Hylobius abietis feeding were studied. Also the ability of homokaryotic Heterobasidion spp. isolates to infect mature conifer hosts and elicit defensive responses was investigated. Terpene and transcript profiles of Scots pine to H. annosum s.s. and H. abietis challenge were studied, and a customised oligonucleotide microarray with 36.5K cDNA elements designed based on the P. taeda transcriptome was used to study the Scots pine transcriptome. The used homokaryotic Heterobasidion spp. isolates were able to colonize and evoke defence responses in the host trees with varying levels of susceptibility. Insect feeding and fungal inoculation induced terpene production in Scots pine. The results indicated that high accumulation of terpenes is not necessarily an effective defence against H. annosum, but δ-3-carene might be associated with higher tolerance to H. annosum in Scots pine. Only few genes related to terpene synthesis were induced in response to H. annosum infection and weevil feeding. Induction of genes related to biotic and abiotic stress responses indicated a wide transcriptomic reprogramming in response to fungal infection and weevil feeding. Genes related to signal perception and defence responses were induced especially in the trees less susceptible to H. annosum inoculation. In addition to these genes, Scots pine δ-3-carene synthases are promising candidates for further research on the Scots pine resistance to H. annosum.

Grantor dc:publisher

Helsingin yliopisto

Year dc:date.issued

2015

Author dc:creator

• Keriö, Susanna

• metsäpatologia

Statement dc:rights

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• Publikationen är skyddad av upphovsrätten. Den får läsas och skrivas ut för personligt bruk. Användning i kommersiellt syfte är förbjuden.

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/10138/158279

OAI record oai:identifier

https://helda.helsinki.fi/server/oai/request?verb=GetRecord&metadataPrefix=dim&identifier=oai%3Ahelda.helsinki.fi%3A10138%2F158279