ATTACK OF THE CLONES Challenging new episode in our course ! Clonal Forestry Dag Lindgren

Clones in Nature

Clones dominated the early flora

 Natural cloning in conifers is rather rare  In Scandinavian forest ecosystems clones are most characteristic of the understory herbaceous vegetation, where they can be dominant  3-15 genotypes in a population represents a typical natural situation

Clones in culture

Examples of Agricultural Monoclonal Successes  ‘Bartlett’ or ‘Williams’ pear  discovered 1770, 75% worldwide crop  ‘Red Delicious’ apple  origin 1870, 50% worldwide crop  and many many more….

From the history of clonal forestry  The first known use of vegetative propagation for forestry purposes was with Sugi (Cryptomeria japonica D. Don, a conifer) in Japan, where it is natural, in the 15 th century.  Vegetative propagation of poplars (Populus sp.) has a long history in Europe. Organised clonal forestry started in the beginning of the 20 th century

Examples of clonal forestry SpeciesAreaMagnitude EucalyptsSouth America, South Africa, Portugal… Around 15 million ha (half of plantations) Radiata pineNew Zealand60 % of plantations

Eucalyptus clones in Brazil

Eucalyptus monoclonal block mosaic in Brazil

Some reasons for a forester to use clonal forestry  To produce a more uniform product;  To improve the forest by using a genetically better planting stock;  To get customer-tailored improved material.

A uniform product…

Improved clones have advantages over improved seedlings!  Little time lag between selections in the breeding and practical forestry;  Short time span to deploy the gain achieved by breeding (get bulk of improved copies);  Flexible for variations in plant consumption;  Eliminate problems with variations in seed production;  Eliminate problems in reproductive output or reproductive phenology of trees in seed production unit;

Possible advantages with clonal forestry  Eliminate selfing;  Eliminate undesired unimproved pollen;  Relatedness among selections little problem;  The market for a bred material can be small  Tailored varieties (no costumer too small...)  Choose the level of diversity desired (often uniformity)  Mass-propagation of expensive but good seeds  Possible to use non-additive variance (like hybrid effects and dominance)  Exploit the additive genetic variation better

Possible advantages with clonal forestry  Choose clones which do not waist resources on sex  Create "physiologically programmed” types  Different cloning methods offer different options  Higher genetic gain (see above)  Combine characteristics which seldom are combined  Test in different environments and choose for wider adaptation (ecovalence)

Comparison clone mix and seed orchard

Other reasons  Cuttings may be morphologically different, e.g. now insecticide use on conifer plants will be more restricted (Pyrmetrin); Cutting plants have thicker bark and more sturdy stem base, and are less harmed, and may possible constitute a solution. This may become the main reason for use of cutting Norway spruce plants in Sweden  It may be easier to make cuttings than to get seeds

Often increased costs  More moments  Clones must be conserved while tested  Legal demands often multiply costs  For many species - expensive propagation

Restrictions for clonal forestry  Experience over long time and large areas is needed, but accumulates slowly over time  Commercial and legal problems considerable and larger than with seeds  Get into problems with opinions, symbol of exploitation of Nature, "clone" is a dirty word  Not so profitable in practice as it appears from theory

Risks and uncertainties  Physiological state matters  Propagation technique may matter for result  Storage technique. Storing genotypes while testing costs money and change characteristics.  Somaclonal variations  State of ortet may matter  Juvenile age selection may give secondary effects  Ecologic consequences? (probably limited)  Specific pests and diseases may be favoured by some clones and that they are repeated in stands and even spread from them  What happens at mature age? Often lack of mature field trials.

How many clones?

Genetic diversity in a stand is likely to favour production  A single genotype demands the same things at the same time, thus inefficient site use!  In a mix another genotype may take over the ecological space left by a failed genotype.  A disease or pest is expected to spread faster in a uniform crop.  Single clones have rather high G*E interaction thus may perform inexpectly bad under some conditions

Clone number Genetic and commercial Gains Plantation Failure

Too much diversity in plantations?!  Most crop- and many forest managers do not like diversity  Uniform trees means better economy and simpler forestry even if biological production is lost  The genetic superiority of superior clones is much larger than the foreseen expected loss by uniformity.  The demand for “high diversity” in intensively managed forests may be very expensive in lost future gain  Uniform crops are easier to handle legally and commercially

Better science possible  Replications  Reproducibility

A tool for a more effective breeding!  Used for seed production  Gains faster realized  Clonal test means testing the sum of genes deployed, progeny testing often are confounded by paternal genes just contributes to noise  A seedling is genetically unique; clones can be optimally replicated.  Clonal test gives in practice much information about ability to transfer gene to progeny  More efficient use of the variation occurring after sexual propagation

A tool for a more effective breeding!  The efficiency of clonal testing depends on costs  Collaborators instead of competitors (non-egoistic clones)  Test on many environments and choose for wider adaptation  Test in the field and cross in the archive  Combine wood in the field and reproduction in archive  Biotechnical breeding - like transgenetic trees - becomes more feasible

Test size (plants) Breeding value Clonal selection Phenotypic selection Comparison (at the same dimensioning) of clonal or seedling based testing for the Swedish Norway spruce long term breeding program. Clonal testing adds around 30% to gain. (Rosvall 1999)

Cutting…

Green-house for cutting production

Clones may be made from somatic embryogenes

Acknowledgements Darius Danusevicius