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RESROBS
Resistance of spruce to root and Butt Rot disease

This research explores resistance to infection by Heterobasidion spp. in clones of Norway and Sitka spruce. Clones will be inoculated with H. annosum, H. parviporum or H. abietinum and the extent of pathogen growth and lesion development measured. Resistance of clones will be related to qualitative analysis of terpenes. Quantitative trait loci / Amplified Fragment Length Polymorphism (QTL/AFLP) maps will be used to determine molecular markers for resistance. Post-infectional responses of clones will be determined by localising the accumulation of pathogenesis-related proteins and measuring the rate of development of bark boundary and xylem barrier zones to infection. Resistance of xylem to degradation by the pathogens will also be assessed. These data will be used to analyse inheritance of resistance, and to develop methods to predict inheritance of resistance based on experimentally determined markers.

Objectives
The aim of RESROBS is to exploit the natural resistance to root and butt rot, caused by Heterobasidion species, present in populations of the economically important conifers Picea abies and P. sitchensis cultivated in European forests. The objectives of this RTD action are:
To test clones of Norway and Sitka spruce from tree breeding programmes for resistance/susceptibility to root and butt rot caused by Heterobasidion annosum, H. parviporum and H. abietinum using glasshouse and field inoculations.
To elucidate the inheritance of resistance/susceptibility to root and butt rot amongst progeny of Picea abies and P. sitchensis from breeding programmes using statistical analysis software packages.
To develop protocols for predicting the heritability of resistance/ susceptibility in proposed crosses, based on genetic data from inoculations and biochemical/molecular data.
To establish marker protocols allowing the rapid and early detection of resistant genotypes in selection and breeding programmes using monoterpene analyses and molecular methods (quantitative trait loci - QTLs; amplified fragment length polymorphisms - AFLPs).
To examine the mechanisms of resistance of relevant host tissues to penetration by, and growth of the pathogen in clones using biochemical methods (accumulation of pathogenesis-related proteins), immunohistochemical methods (localisation of lignification responses), and histological methods (development of ligno-suberised boundary zones in bark; formation of reaction zones in wood; relative degradation of wood in different clones).

Results
Inoculations were made with all European Heterobasidion inter-sterility groups on both mature and juvenile trees. Tree phenotype and genotype significantly influenced fungal growth. Data from a Swedish inoculation trial were analysed using SAS Proc GLM for phenotypic analysis and Proc Mixed for genotypic analysis and to obtain Best Linear Unbiased Predictors (BLUPs) for the clones. Nine monoterpenes were identified in secondary phloem tissues of Picea abies. The major constituent was a-pinene, with considerable proportions of b-pinene, D-3-carene and myrcene. The work suggested that D-3-carene may be a useful maker for susceptibility in P. abies. Protocols for DNA extraction from Picea abies materials, primer-enzyme combinations and PCR conditions for AFLP analyses were optimised in collaborations between Partners 2 and 3. Using these protocols DNA sequences of AFLPs were identified and their functions inferred.
Methods for extracting pathogenesis-related proteins from tissues have been optimised, and activities of certain enzymes putatively related. A Real Time-PCR method for quantitation of the pathogen in host tissues was developed, an essential technique to determine true levels of resistance/susceptibility, and used to show that less fungal mycelium occurred in less susceptible compared with more susceptible clones of Norway spruce. Improved methods for embedding and sectioning bark tissues were developed to give sections of a quality suitable for image analysis. Differences in the fine structure of root vs stem bark were observed in both species of spruce.

Classified in CROP PESTS AND DISEASES, FORESTRY, GENOMICS, QUANTITATIVE APPROACHES AND MODELLING

Scientist responsible for the project

Dr. STEPHEN WOODWARD
University of Aberdeen, Biological Sciences
AB24 4FA Aberdeen
United Kingdom (The) - GB

Phone: +44 1224 272669
Fax: +44 1224 272685
E-mail: s.woodward@abdn.ac.uk

References

Project ID QLRT-2000-00241
Organisation University of Aberdeen
Area 5.3.1
Start date 01 September 2001
Duration (months) 36
Total cost 1 936 153 €
Total EC contribution   1 276 565 €
Status Completed
Web address of the project   http://www.abdn.ac.uk/resrobs/

The partners

  • The Forestry Research Institute of Sweden, Sweden - SE
  • Instituo Miglioramento Genetico Piante, Italy - IT
  • Norwegian Forest Research Institute, Norway - NO
  • Swedish University of Agricultural Sciences, Norway - NO
  • National Agricultural Research Foundation, Greece - GR
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