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FAIR-CT97-3823
Characterisation and validation of wood properties in birch for industrial use and future breeding |
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Contract No: | FAIR-CT97-3823 |
| Date Prepared: | May 2000 | |
| Source: | Second Annual Progress Report Abstract |
Introduction
The main target of the project is to improve the quality of birch wood available to the pulp, paper and board industries through an understanding of wood properties and development of molecular markers associated with specific wood quality traits.
Activities
The wood structure of trees growing in the widely different conditions prevailing in Sweden, Finland and Germany, and of trees of a single micro-propagated genotype, now ten years old, growing in Sweden and the United Kingdom will be fully characterised. The industrial partners will determine the properties of the wood for pulp, paper and veneer. Molecular markers in relation to wood characteristics will be identified as well as markers for phase changes associated with to the transition from juvenile to mature wood production and its effect on industrial wood properties. The selected and characterised trees will be propagated in vitro both from branches and, if possible, from stem sprouts, to establish field trials to be used for future selection and breeding.
Progress
The material for marker analysis has been classified and selected, in vitro rooted birch plants of various genotypes have been produced and delivered for use in the field trials. These plantlets have been successfully acclimatised in the greenhouses prior to field trials.
Anatomical analysis showed that an increase in fibre diameter was correlated with an increase in fibre length from pith to bark, while vessel length and ratio of vessels to fibres did not increase from pith to bark of the "Mother" tree. The fibre length and diameter of the LJKA, UKC and UKS trees were similar to the Mother tree despite that these trees were ten years younger than the Mother tree, This is probably due to the site differences, in which the UK trees were grown on an agricultural site while the "Mother" tree was grown on a forest site. This indicates that birch trees can be harvested much earlier when growing under good conditions.
Fibre length in S2, G2 and F2 increased rapidly for about fifteen years, then continued to increase gradually. In the oldest tree (50 years), fibre length was still increasing at the outermost growth ring. Fibre diameter in all the trees increased less markedly. Comparison of mean fibre length between the "Mother', S2, G2 and F2 trees showed that the "Mother" tree had a shorter fibre length. The preliminary analysis showed that opposite wood consistently had higher lignin levels than reaction wood, except in the case of G2.
Analysis of the basic chip density showed a distinct difference between the genotypes and between the juvenile and mature wood, in which the wood density decreased with increasing content of juvenile wood. The UK trees showed a lower basic density compared to the selected genotypes.
Results in kappa number, viscosity, yield and brightness for the unbleached pulps showed clear differences between the genotypes. In general, a higher kappa number, but lower viscosity, yield and brightness were found for samples taken from the top part of a tree with more juvenile wood compared with the bottom part samples. Also the fibre length, fibre coarseness and fibre strength were lower for the top part samples. Analysis on bleached pulps displayed that, despite of different kappa number after cooking, a good bleachability was obtained for all the genotypes except for the genotypes UKA, LTKC and UKS which had the highest content of juvenile wood. The final conclusion for veneer characterisation has yet to be reached.
The hoped for phase-specific marker MVAX3 isolated from oak was found not to be suitable.
So far, 45 cDNA clones have been isolated from cambial tissues of the birch genotype S3. The majority of them has been screened by restriction digestion and up to 30 have been used in Northern Blot analysis. A number of these cDNA fragments have been sequenced. Several have been identified as up-regulated in mature cambial tissues. Furthermore, the RDA subtractive process has been performed in order to isolate cDNA fragments that are up-regulated in juvenile cambial tissues. These fragments remain to be cloned and analysed by restriction digestion and Northern blot analysis. The birch genomic DNA library construction is now complete and analysis of clones indicate that the library is representative of the birch genome.
The setup and qualification of AFLP technique is complete. The large genome method would be preferred in the future tasks. General variability of the marker profiles within the B. pendula species has been compared to that between different Betula species in order to be able to evaluate the resolution power of the different AFLP markers. The results showed that all markers, which have good technical performance, also have good resolution both within and between the species. Leaf samples from the F2 family of the selected cross V5818 x V5816 were collected in June, 1999 for identification of AFLP profiles for trees of breeding trials. So far, AFLP profiles have been completed for the parents and pedigree with six marker pairs.
The task of matching markers with QTLs is underway.
For the breeding strategy task, the analysis of the profitability of using clonal tests for the breeding population has been done. The technique for the analysis has been developed. More analysis specifically for quality birch has been made. A worksheet has been constructed from which the benefits of clonal testing could be evaluated. Information was collected about current breeding strategies and the relevant parameters for birch and quality birch. A number of analyses of the value of cloning for testing the breeding population have been done using this worksheet and the stochastic breeding simulator POPSIM.
The participants performing the field trials have chosen sites which were prepared for the planting in spring 2000.
Achievements
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