The project aims at the genetic improvement of fast growing poplars, having particular regard to resistance to pests and diseases. Several approaches are considered in 5 tasks:
Task 1 Genetic Transformation.
The objective is to introduce foreign DNA into commercially desirable poplar stock by means of Agrobacterim tumefaciens as gene vector, a process that has already proved viable for several poplar species. Genes from Bacillus thuringiensis and proteinase inhibitors would confer resistance to insect pests, especially Lepidoptera and Coleoptera; sequences derived from Poplar Mosaic Virus would slow down viral replication in transformed poplars. Tissue-specific or wound-inducible promoters will be studied too, as a means of avoiding unnecessary expression of exogenous DNA.
Task 2 Genetics of Resistance and Virulence.
Stable resistance or tolerance to diseases in long-lived crops such as poplars should be achieved by multiple genes (horizontal resistance), possibly with distinct mechanisms of action. The genetic components of resistance to economically important pathogens (Xanthomonas populi and Melampsorae sp.pl.) will be analysed, as well as the correlations between field susceptibility and the results of artificial inoculations in vivo and in vitro. Molecular (RFLP and RAPD) and biochemical (phenolic compounds) markers will be studied in relation to resistance to leaf and bark diseases and insects pests, with the aim of developing early tests for clonal selection and for the orientation of breeding work.
Task 3 Improvement of Breeding Tools.
Poplar breeding is largely based on inter-specific hybridization, which is often limited by sexual incompatibility; the project addresses both pre-fertilization barriers, such as pollen/pistil interactions, and post-zygotic causes of embryo abortion: the techniques to be investigated include the use of Mentor pollen, stigmatic and non stigmatic pollination in vitro, embryo rescue in vitro. The task includes also the development of techniques for long-term storage of germplasm: cryo-preservation of pollen and seed; maintenance of in vitro collections with minimal requirements for periodical subculturing.
Task 4 Pathogen Variability and Evolution.
Variability in pathogenic power is already known to exist for Xanthomonas populi and Melampsora rusts and is in question for X.campestris and Marssonina brunnea. The project will explore the genetic variability of pathogens as a necessary step for understanding their potential evolutionary ability and for developing breeding strategies for stable resistance. Isolates from different geographic areas, and in some cases, strains obtained by recombination in confined environments will be studied: differences of aggressivity towards common sets of poplar genotypes will be investigated, also with the use of molecular techniques (PCR & RFLP)
Task 5 Clone x Environment Interactions.
A network of clonal trials already available in sharply different ecological conditions in four countries will help determine the main limiting environmental factors, as well as the clonal response to them. Data concerning annual growth and phytosanitary status vis à vis of climatic and pedological factors will be fed into a GIS data-base and will orientate the future choice of clones and sites for commercial poplar culture.
Funding SchemeCSC - Cost-sharing contracts
GU10 4LH Farnham
34346 Hann Münden
SN2 1EU Swindon