Balanced Breeding in a Grand Parent Perspective.

- Consideration for Swedish Scots pine breeding

Dag Lindgren

Förädlingsutredningsmöte Uppsala 08-05-14

Revised

Study• Status: submitted, minor revision asked for, resubmitted

with authors Lindgren, Danusevicius and Rosvall.• Swedish pine breeding is target• SPM to simplify calculations• Cycle time is 18 years• Size of breeding population is a variable to be optimized,

not preset by the number of founders• Selection of good phenotypes in good families (“combined

selection”)• Reference (base line) is a phenotypic strategy (strategy 3),

which appear as one of the most promising of earlier considered strategies (paper in CJFR 2007 with participation of Gunnar Jansson).

• Variant of “strategy 5”

(…) (…)F1

SPM with parental balance(almost current Swedish program)

Grand parents (=founders), F0

Mating grand parentsSelect and mate 2 best sibs

(…) (…)F2

(…)(…)

2nd rank family

(…)

1st rank family

(…)

3rd rank family

(…)

nth rank family

(…)

Multiple SPMsGrandparents

=founders

Green trees show pedigree

F0

F1

F2

Cross e.g. 4 best sibs in the 2 best families (2 parents per grandparent)

Cross 4 best sibs

• Note that retrospectively SPM and multiple SPM (strategy 5) give identical pedigrees, thus identical increase of coancestry.

• Simple SPM (strategy 3) is a special case of multiple SPM (strategy 5) with 2 parents per family.

10

5

14

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0 5 10 15 20 25

Low budget

High budget

2

Medium budget

Families & parents cost nothing

Number of parents per selected family

An

nu

al p

rog

ress

(%

)

2=phenotypic

4

7

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0 5 10 15 20

Low budget (impossible)

Medium budget

High budget

2

Families & parents are expensive

Number of parents per selected family

Annual p

rogre

ss (%

)

Conclusions• Strategy 5 seems VERY promising and can beat phenotype strategy (strategy 3)

with 20-70 percent gain. Variants of strategy 5 which are still more efficient can be constructed.

• Strategy 5 can be implemented immediately. Select in field trials and graft in crossing archive. Make new selections when grafts mature for pollination, and harvest pollen from new selections.

• The actions are the same as for Strategy 3 (phenotypic selection), but more selections are done with strategy 5.

Recommendation (Dag): Start this immediately for the most suitable objects! I suggest setting the breeding population to 3 times the founders from now. When more studies, theoretical results and experiences (e.g. on male flowering in young trees) have accumulated, it may be increased. But that 3 times is better than no increase is safe enough to act on immediately. Even if it does not work, where are escapes to other strategies.

Note: The circumstances may make it motivated to use other strategies in specific cases, but this conclusion is safe enough to have it as main objective.

But Darius and Dag suggested Strategy 4 to be 20% better than phenotypic……. and this quantitative estimate seem uncertain… Can

the prediction on Strategy be trusted?• The estimate 20% was in “genetic merit” (take diversity loss at cycling in

consideration), including a heavy penalty for cycling. It also assumed a high cost for cycling. Thus and for other reasons the quantitative magnitude of the advantage may be debated, but strategy 4 still seems recommendable compared to Strategy 1, 2, and 3.

• Strategy 4 here assumes progeny-test following open pollination which may – or may not - be of some importance compared to the results by Darius and Dag.

• The current POPSIM which alternative comparisons are based on is based on genetic gain only, while Breeding cycler considers costs and time and gene diversity and optimizes things.

• The gain predicted is much higher! this variant of strategy 5 seems at least 20% better! But it may be 70%!

• The calculations are simpler! The conclusion is logic! (see next slide).• I make serious mistakes the whole time and there are detected mistakes in

Breeding-cycler, so it should not be taken for granted that breeding cycler predictions are right. However the frequent mistakes have till now not changed the main results.

• The scenario may be unrealistic, it may always happen.

Timing a la Curt 0804Strategy 3+2 4 3 1 2 5

Phen + Prog tandem

Phen preselection+

Prog

Phenotypic Progeny

Base

Progeny

IntensCombined

Phen and progeny

Cycling time, total

46 37 20 33 26 20

Sel age

Phenotype

13 15 13

15

Sel age

progeny

12 15 12 12

Use of cycle for testing

54% 81% 65% 36% 46% 75%

Förädlingsstrategier

1.

2.

3.

4.

5.

DPM

6.

7.

DPM

21-40 upprepasGen.tid: 38/ 2=19

Fältförsök

Korsning och frömognad

Växthus & friland

Mellanstock-arkiv

Arkiv

År

40x50=20000

10x50=500 50050

PC

250 (5x2x250)

40x50=20000PC

50050

200x50=10000 5x8 + 5x8 =40+40

13 (5x2x12.5)

100x50=5000 5 st/fam

5x50=250

40x250=10000

13 (5x2x12.5)

5x8 + 5x8=40+40

100x50=5000 6st/fam

38 (5x2x37.5) 100x300=30000

Sticklingprod.

14x40x50=28000

13 (5x2x12.5)

12x40x50=24000

2x40x50=4000

♀ 75+, ♂ 75+

10x50=500

Kottinsamling

5x8 + 5x8=40+40

DPM

DPM

DPMDPM

DPM

DPM

Mätning

50

50

50

50

50

150-300 13 (5x2x12.5)

1 st/fam

Picture constructed by Johan Westin and Curt Almqvist May 2008

Efficient use of breeding cycle

• The breeding cycle has two parts. Recombination and selection based on field test. Only selection based on field test generates gain. A most important component of a strategy is to use the breeding cycle with gain generating field testing.

• Progeny-testing utilizes the breeding cycle for field testing very inefficient. Phenotypic selection is better.

• But integrating phenotypic and progeny selection in a single cycle, as done in strategy 4 and 5, means that most of the breeding cycle is use for field testing and thus likely to be much more efficient.

• Making them in tandem is not as good use of the breeding cycle.