Towardmoreefficient treebreeding Matti Haapanen
"Tree breeding is a simple procedure, which becomes complicated only when we try to make our activities efficient" Bob Campbell
Treebreeding Sustainablemanagement of genetic variation to generate and multiply for operational planting high-yielding and well adapted genotypes Improved forests Deployment Seed orchards(cloning) 15 years Evaluation Genetic field testing 15 years Selection for breeding& deployment 5-10 years Wild forests Mating Controlled crosses
Efficientbreedingin a nutshell Generate and deploy maximum genetic gain per time at acceptable levels of diversity and cost Notquitethatsimple. Why?
Challengingpropertiesof trees o Late expression of valuable traits Moderately long testing times o Late sexual maturity Prolonged generation intervals o Climatic adaptation Separate populations for different target environments/climates o Physical size Large scale field trials and clone archives o Slow, costly mass propagation Delayed transfer of gains to forestry
Researchon efficienttreebreedingover the past25 yearshasgreatlyimproved ourunderstandingof workable long termstrategies
Source: Review of the Swedish tree breeding programme 2011
Elementsof efficientbreeding o Breeding populations reasonably sized (<=1000) o Long-term genetic diversity managed by subpopulation structures and selection o Simple and straightforward mating designs o Statistically efficient field test designs o Clonally replicated test materials (when feasible) o The best trees are given the preference Positively assortative mating Unbalanced resource allocation Linear deployment
Whenstrategymeetsreality o When breeding plans are revised, breeding has continued for decades o Existing breeding materials are usually formed of heterogeneous groups (age, generation, accessibility) o More than one strategy / species is often efficient o Low cost (low gain) strategies Species and regions with less reforestation and productivity o Flexibility is the key word
Smoothgenerationturnover o Genetic field testing takes ~15 years o Sounds inefficient but is not o Testingtimeis workingfor the breeder o Older data are better correlated with goal traits o Older selections closer to sexual maturity o Evaluation. Selection. Mating
Finnishsprucebreedingmodel Clone trial #1 Clone trial #2 Clone trial #3 Clone trial #4 Clone trial / Breeding archive #5 Clone testing 30 candidates / family Data Seed orchards Selection at age 15 genetic thinning Promotion of flowering Complementary grafting / topgrafting 2-pair matings in situ Full-sib families
Mating o The most challenging phase of the breeding cycle
Improved forests Deployment 15 years Evaluation 15 years Selection 5-10 years Wild forests Mating
Rolling FrontBreeding (Borralho & Dutkowski 1998) o Trees reach sexual maturity at different ages o Breeders like to deal with distinct generations o Latecomers slow down breeding o RFB: Mate when you can Establish new trials immediately o This results in more genetic gain per time (according to computer simulations) many small trials, complex data risk of breeding for early sexual maturity? o Breeding tends to drift toward some version of RFB
Whynotpassoverfieldtestingand look directlyat the tree sgenes?
Markerassistedselection o Moleculartoolshavebeenpromisedto revolutionise tree breeding ever since the 1980 s o What happened? Inadequate association between marker genotypes and phenotypes Most valuable traits of trees are polygenic and have low heritability Low selection power Cost of genotyping vs. large breeding materials o MAS neverbrokethroughin the realtreebreeding o Will Genomic Selection change this?
Somethoughts o Genomic selection will not make field tests useless Marker phenotype associations deteriorate, must be re estimated in every generation? Selection for markers alone is risky o Genomic preselection? Smaller, less expensive trials testing the most promising genotypes o Breeding process will not be accelerated? o In conifers, GS requires tens of thousands of SNP markers o Additional gains vs. cost of genotyping
Wheremarkersarebecominguseful o Parentage analysis(unknown fathers) o GBLUP Use true genomic relationships to more accurately predict genetic merits o Forward selection in families with incomplete pedigree (OP, polycross) o The Breeding without breeding concept (El Kassaby et al 2006) Use open pollination instead of artificial crosses Phenotypic selection DNA fingerprinting pedigree reconstruction Specific situations
Whilegenomicsis fascinating let snotforgetphenomics
3D laserscan technologies are coming
Cross section of tree heights in a Scots pine realized genetic gain trial in Punkaharju, obtained by means of an aerial laser scanner
New technologies will enable us to collect masses of data from breeding trials in a fraction of effort compared to today s routines?
Finalpoints o Research on efficientbreeding has provided a sound basis for breeding of Norway spruce and Scots pine o Many paths to choose from higher genetic gains normally come with a price tag o Genomic tools are crawling into operational tree breeding. Their future role will depend on costs vs. gains o Phenomic tools are also being developed o Efficient breeding is about good planning
Thankyou