First pages is

‚Vorbemerkung‘

prelude

intro …

Comments on categorization of plant breeding methods,

based on what ‘they’ taught me back then …

Wolfgang Link wlink@gwdg.de 2021 itoC

1

With the following three pages I want to raise your

awareness and to prepare you to

● mind the details

● use terms properly

● apply such enhanced awareness

when it comes to scrutinize the panorama, to overall-

picture of ‘plant breeding’; and when you want to get

orientation, to get help in navigating the realm of

plant breeding’.

►sometimes it is good

to mind the details

3

►sometimes it is good

to mind the details

4

►If you can, think and speak clear, to reduce

misunderstandings, frustration, loneliness,

loss of time and money, feuds, wars, other

misfortunes. Polite clarity improves your live.

5

I test my potato

individuals in five

places per season

… five times

excavating, moving

and replanting, poor

potato plants

Relations between various classifications systems for the methods

of plant breeding (Schnell, 1982)

Types of breeding

according to

Fruwirth (1922)

Classifications of

Methods according

to Roemer (1941)

Classification system

according to

Hoffmann/Mudra/Plarre

(1971) Upgrading breeding

(Veredlungszüchtg.)

Selection Breeding

(Auslesezüchtung)

Selection Breeding

(Auslesezüchtung)

Ne

w-C

ult

iva

r B

ree

din

g (

Ne

uzü

ch

tun

g)

By separation

germplasm

pools

♦ For ‘selfers’ Clone selection

Mass selection By choice of

spontaneous

variants

♦ For ‘outcrossers’ Single-plant selection with

progeny testing

By crossing

By grafting

Breeding by crossing

(Kreuzungszüchtung)

Breeding by cross.

(Kreuzungszüchtung)

♦ For ‘selfers’ ♦ For ‘selfers’

♦ For ‘outcrossers’ ♦ For ‘outcrossers’

♦ interspecific

crossing

♦ Heterosis breeding

♦ intersp. crossing

Polyploidy breeding

Mutation breeding

Mutation breeding

♦Genome mutation

♦chromosom mutation

♦point mutation

♦plastide mutation 6

The page before and after shows that, very

seriously, breeders strove for order and structure

and clear view across the protocols, ideas,

strategies, techniques, recipies and so on of plant

breeding activies. For sure one argument was to be

better able to teach plant breeding.

Teaching others is, of course, first and mainly

teaching oneself.

See the separation between ‚breeding by upgrading

or selection‘ (by and by improving a standing

cultivar) and ‚making new cultivars‘; and inside the

latter, the separation between exploiting standing

diversity vs. creation new diversity by crossing and

subsequent segregation. See the first shy hints to

sepearte self-fertilizing from cross-fertilizing crops.

Relations between various classifications systems for the methods of plant breeding (Schnell, 1982) Types of breeding according to Fruwirth (1922)

Classifications of Methods according to Roemer (1941)

Classification syst. acc. to Hoffmann/Mudra/Plarre (1971)

Classific. Syst. acc. to Breseghell, 2013

Upgrading breeding (Veredelungs-züchtung)

Selection Breeding (Auslese-züchtung)

Selection Breeding (Auslese-züchtung) Breeding

based on observed variation

Ne

w-C

ult

iva

r B

ree

din

g (

Ne

uzü

ch

tun

g)

By separation germplasm pools

♦ For ‘selfers’ Clone selection

Mass selection

♦ For outcrossers’ By choice of spontaneous variants

Single-plant selection with progeny testing

By crossing By grafting

Breeding by crossing (Kreuzungs-züchtung)

Breeding by crossing (Kreuzungs-züchtung)

Bree-ding by crossing

Bree-ding based on genes or mar-kers

♦‘selfers’ ♦ ‘selfers’

♦ ‘outcrossers’

♦‘outcrossers’ ♦ heterosis breedg.

♦ intersp. crossg. ♦ intersp. crossing

Polypl. breedg.

Mutation breedg.

Mutation breedg. ♦Genome mut. ♦chromos. mut. ♦point mut. ♦plastide mut.

8

9

Although Wageningen is a very highly appreciated place

for plant breeding research, what is given in the text last

page would imho better not be termed as ‘methods’ but

rather as ‘techniques‘ (!proper use of terms).

You can release new diversity by mutagenesis or by

genome editing in potatoes (clone breeding) as well as in

lentil (line breeding); and so on. Subdivide plant breeding

according to ‘yes or now’ application of such techniques

helps little to navigate.

You see the flaw in this enumeration:

Chairs, tables, sofa, cupboards, varnish-oil paint.

Then …

you see the flaw in this enumeration:

Line breeding, clone breeding, hybrid breeding, mutation

breeding. ☺

Now … serious

Comments on categorization of plant breeding methods,

based on what ‘they’ taught me back then

Wolfgang Link wlink@gwdg.de 2021 itoC

11

Let us get some orientation, coordinates, longitude, latitude!

Heiko Becker,

Pflanzenzüchtung

1993; 2011; 2019

Lucky you are in case

you can read German.

13

‘TYPES’ OF CULTIVARS & METHODS AND CATEGORIES OF PLANT BREEDING The reproductive system is the current criterion. Classification used in textbooks of ● Robert W. Allard ● D.A Sleper and J.M Poehlman ● H.C. Becker

Four ways to produce the ultimate commodity for sale to the farmer (the certified seed, the certified planting material). Certified tubers of potato are is produced by natural vegetative propagation Certified seed of soya is produced by natural self-fertilization Certified seed of maize is produced by controlled cross-fertilization Certified seed of clover is produced by natural cross-fertilization

FOUR CATEGORIES OF BREEDING Vegetative propagation results in clone cultivars. Self-fertilization results in line cultivars. Controlled crossing of ♀ and ♂ parent results in hybrid cvs. Panmictic cross-fertilization results in population cultivars.

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‘TYPES’ OF CULTIVARS & METHODS AND CATEGORIES OF PLANT BREEDING The reproductive system is the current criterion. Vegetative propagation results in clone cultivars. Self-fertilization results in line cultivars. Controlled crossing of ♀ and ♂ parent results in hybrid cvs. Panmictic cross-fertilization results in population cultivars.

Natural mating system Mode of propagation Type of cv.

Self-fertilization Self-fertilization Line

Artificial / controlled crossing

Hybrid

Cross-fertilization Panmictic / open cross-fertilization

Population

Vegetative reproduction

Vegetative propagation

Clone

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The four categories of plant breeding methodology

Natural mating system Mode of propagation Type of cultivar

Self-fertilization Self-fertilization Line

Artificial crossing

Hybrid

Cross-fertilization Open cross-fertilization

Population

Asexual reproduction Vegetative propagation

Clone

Crucial Question Line

breeding Population breeding

Hybrid breeding

Clone breeding

Is heterosis a major factor in resulting cvs.?

NO Yes Yes Yes

Would cvs. consisting of just one genotype be feasible?

Yes NO Yes Yes

Can the plants of a cv. be used for its own propagation?

Yes Yes NO Yes

Are resulting cvs. propa- gated by seeds?

Yes Yes Yes NO

Allard, R.W., 1999. Principles of Plant Breeding. 2nd

Edition. John Wiliey & Sons. Sleper, D.A. and J.M. Poehlman, 2006: Breeding Field Crops. 4

th Edition. Blackwell.

Becker, H.C., 2019: Pflanzenzüchtung. 2. Edition. Ulmer. 16

Clone cv. Line cv.

Bulk method

Population cv.

(Synthetic cv.) Hybrid cv.

Inside each category, we have different methods. Example:

‘pedigree method’ and ‘bulk method’ are two methods in the

category of line breeding 17

Clone cv. Line cv.

Bulk method

Population cv.

(Synthetic cv.) Hybrid cv.

With the comparison of methods within and across

categories we come from mere ‘method’ to ‘METHODOLOGY’

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Clone cv. Line cv.

Bulk method

Population cv.

(Synthetic cv.) Hybrid cv.

1 Provide initial

variation

2 Select potential

parents-of-cvs

3 Test experi-

mental cvs.

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The methods can, across categories, be displayed as sequence

of three phases, allowing for instructive comparisons

Clone cv. Line cv.

Bulk method

Population cv.

(Synthetic cv.) Hybrid cv.

1 Provide initial

variation

2 Select potential

parents-of-cvs

3 Test experi-

mental cvs.

Example: to release genetic variation, it takes one (clone) or two (line)

generations or, in cross-fertilizing crops, breeders usually have diverse

populations (germplasm pools) right at hand 20

Clone cv. Line cv.

Bulk method

Population cv.

(Synthetic cv.) Hybrid cv.

1 Provide initial

variation

2 Select potential

parents-of-cvs

3 Test experi-

mental cvs.

21

Clone cv. Line cv.

Bulk method

Population cv.

(Synthetic cv.) Hybrid cv.

1 Provide initial

variation

2 Select potential

parents-of-cvs

3 Test experi-

mental cvs. Premature ;-)

openig of

present Long blind flight

22

Clone cv. Line cv.

Bulk method

Population cv.

(Synthetic cv.) Hybrid cv.

1 Provide initial

variation

2 Select potential

parents-of-cvs

3 Test experi-

mental cvs.

23

Clone cv. Line cv.

Bulk method

Population cv.

(Synthetic cv.) Hybrid cv.

Navigate via per se performance, via

GCA and SCA.

Navigate via prediction

Today: Genomic Prediction.

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Maybe … see below

So, then … rehearsal. What is SSD? “Single Seed Descent” is a breeding method in category line breeding “Breeding of Synthetics” is a method in category population breeding “Three-Way-Cross hybrid breeding with Genomic Prediction of trans-pool GCA” is a ver-sion of a method in category hybrid breeding. Clover is easy to be cloned, the components of clover synthetic cultivars are clones. Hence: clover breeding = clone breeding? No! Farmers buy seed (not planting material); they sow (not plant) a clover field. Certified clover seed is produced by open (near-to ran-dom mating) fertilization. Clover breeding is population breeding. Nota bene: It is always good to make a difference between sowing and planting.

If (I mean: “if”) potato breeders create diploid homozygotes; and then cross two lines to produce hybrids, and an F1-hybrid potato cv. is then multiplied vegetatively and farmers buy tubers… clone breeding? If potato breeders create diploid homozygotes, mass-cross two lines to produce hybrids, and the farmers buy potato seed and sow them … hybrid breeding? You see, nothing is static, things may change, definitions … may need updates …

26

So, then … rehearsal. Is “Reciprocal recurrent selection with Genomic Preciction of trans-pool GCA” hybrid breeding? No, this is pre-breeding (Vorlauf-Züchtung). Recurrent Selection is Pre-Breeding, not Breeding. “Reciprocal Recurrent Selection” is a method of Recurrent Selection. Recurrent selection is typicylly (not only) conducted with cross-fertilizing crops. Some recurrent selection methods, alas, can be identical to Population Breeding (for in-stance, variants of mass selection).

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It is not self-evident to restrict ‚Plant Breeding‘ to the cultivar-making phase of

breeders‘ activities. In a broader sense, pre-breeding and maintenance breeding,

even further activities may as well be seen as ‘Plant Breeding’.

Yet, then, the four-category-principle is not strictly applicable any more.

So, then … rehearsal. What is “heterosis breeding”? This is a term of a different system of categorization. Heterosis is a crucial factor in clone, hybrid, and population cultivars. Heterosis is only absent in line cultivars. Heterosis is no good identification clue for category. What is “mutation breeding”? This is a term of a different system of categorization. Release of mutation is not a breeding method, it is a technique used in breeding. Release of mutation can be used in all four categories of breeding. What is “CRISPR Cas9-Breeding”? CRISPR Cas9 is a technique to release genetic diversity. What is Tilling, then … same. What is Polyploidie breeding … same, technology. What is marker-assisted breeding … same, is not breeding, is technology. What is Bli-Bla-Blu-Breeding? Same …

28

So, then … rehearsal. If it is not clone breeding, not line breeding, not hybrid breeding, not population breeding, then it is not a Plant Breeding Method and not addressing one of the four categories. Then it may be a method in recurrent selection Or .. it may be one of the very many technologies used in selection and breeding

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