ATTACK OF THE CLONES

Challenging new episode in our course !Clonal Forestry

Dag Lindgren

Clones in Nature

Clones dominated the early flora

0102030405060708090

100Number of families

% of flora

Some large and old plant clones (after Cook, 1985). Species Diameter (m) Age (years) Gaylussacia brachycerium 1980 13 000 Holcus mollis 880 1000+ Populus tremuloides 510 10 000+ Pteridium aquilinum 489 1400 Lycopodium complanatum

250 850

Festuca rubra 220 1000+ Convallaria majalis 83 670+ Calamagrostis epigeios 50 400+ Picea mariana 14 300+ Festuca ovina 8 1000+ Larrea tridentata 8 11 000+

Some natural clonal species in nature (Widén et al, 1994)

Species Genotypes per population (range)

Genotypes found in >75 % of populations

Alnus incana 5 100 Agrostis stolonifera 7,5 (1-15) 0 Antennaria rosea 3,5 (1-11) 0 Betula glandulosa 3 (1-5) 0 Erigeron annuus 14 (13-15) 59 Filipendula rubra 5,5 (1-15) 0 Glechoma hederacea 34,8 (15-98) 0 Oenothera biennis 1,5 (1-5) 0 Oenothera laciniata 6,5 (1-16) 1 Populus tremuloides 31,7 (30-40) 0 Pteridium aquilinum 24,8 0 Rubia peregrina 39,3 2 Rubus saxatalis 9 (8-10) 0 Solidago altissima 10,3 (3-20) 0 Taraxacum hollandicum 1,4 (1-4) 25 Taraxacum tortilobum 3,3 (1-7) 13

Natural cloning in conifers is rather rareIn 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’ peardiscovered 1770, 75% worldwide crop

‘Red Delicious’ appleorigin 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 15th century.

Vegetative propagation of poplars (Populus sp.) has a long history in Europe. Organised clonal forestry started in the beginning of the 20th century

Examples of clonal forestry

Species Area Magnitude

Eucalypts South America, South Africa, Portugal…

Around 15 million ha (half of plantations)

Radiata pine New Zealand 60 % 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

Parameters as current Norway spruce breeding in Sweden

0

20

40

60

80

100

120

140

0 1 2 3 4 5 6 7 8 9 10 11

Generation (=20 years)

breeding pop

10 clone seed orchard

10 clone clonal mixture

Gain (per cent)

Rosvall, Lindgren & Mullin 1998

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 2003.

It may be easier to make cuttings than to get seeds

Often increased costs

More momentsClones must be conserved while testedLegal demands often multiply costsFor 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

PlantationFailure

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

ReplicationsReproducibility

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 archiveCombine wood in the field and

reproduction in archiveBiotechnical breeding - like transgenetic

trees - becomes more feasible

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0 500 1000 1500 2000 2500

Test size (plants)

Bre

edin

g v

alu

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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