Plant Genetic Improvement Methods

Plant Genetic ImprovementWhat it is and what it isn’t

Kevin M. FoltaProfessor and Chairman

Horticultural Sciences Department

kfolta.blogspot.com@kevinfolta

[email protected]

Everyone Loves New Technology

What Plant Genetic Improvement Is

More varieties

Grow better under given conditions

Improved yields

What Plant Genetic Improvement Is

People Think

Improved yields

Plant Genetic Improvement

Breseghello and Coelho, J Ag Food Chem 2013

Methods of Plant Genetic Improvement

What are the major ways we genetically improve varieties?Major methodsSome common examplesStrengths / limitations

How do they compare to each other?

The future of plant genetic improvement

How to talk to the public about genetic improvement methods

Dispelling the Naturalistic Fallacy– This is Nothing New!

Remind audiences that genetic improvement of food is a continuum.

Almost none of the plants we regularly consume originated in North America. Almost all were brought here by humans.

None of the food you eat is like its “natural” form

GM technology is simply the most precise version of an age-old practice of breeding and selection.

Humans have always manipulated crop genetics

Inbreeding

Decreases useful production traits

Lower heterozygousity

Non-specific crosses

Combining the desirable traits from two genetic backgrounds into one.

Problem: Linkage drag

Requires many backcosses to “clean up” genetics

Can require a long time

No regulatory issues

X =

IRRI Images

Non-specific crossesBackcrossing removes undesirable genes/alleles.

Wide genetic crosses

Integrating traits from wild relatives into elite varieties

Problem: Linkage drag

Solution (+/-) marker-assisted breeding

Marker-Assisted Breeding

Association between the likelihood of inheriting a trait and a certain sequence of DNA

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Wide genetic crosses

North America

Chile

Crossing the Impossible

Bridging Crosses- when the desired cross is not possible, finding a sexually-compatible plant, creating the interspecific hybrid, and then crossing the progeny to the other parental genotype.

Embryo Rescue

Fertilization takes place, but embryo is not viable for normal germination.

If given the proper conditions, the embryo can germinate and mature into a plant.

Hybrids between inbreds

B73 Mo17

Iowa Sate Univ photo

Produce plants from inbreeding that are highly homozygous

Cross two inbreds together and get tremendous heterozygousity

Hybrids between inbreds

Polyploids

Increased numbers of genomes in a cell

Can be natural or induced

Examples:

Beans, potato, strawberry, wheat, brassicas, many others

Polyploids

Increased numbers of genomes in a cell

Seedlessness

Wheat breeding

Mutation Breeding

All genetic variation begins with mutation

Mutations can be induced with ionizing radiation or chemicals

May require backcrossing

High lycopene

Seedlessness

Regeneration from single cells

Plant cells can “re-program”

Somatic Fusions

Transgenics

What people usually think of as “GMO”

Addition of a gene, or small number of genes

Transgenics

Can add traits from across species (like the Bt gene for insect resistance)

Can suppress traits or viruses using RNAi (as in the papaya and potato)

GM Crops Available Now

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potato

Keep it Simple– What are the Three Main Traits?

Virus Resistance

Insect Resistance

Herbicide Resistance

(how the traits work lecture online – (google “ UF biotechnology literacy day”)

Strengths Limitations

Virus resistance Works great, no foreign material

Has cut insecticide use by 10-70%

Saves time, labor, fuel. Allows conservation tillage

Can spread to nonGM populations

Pockets of developing resistance

Resistant weeds are a problem in areas.

Insect resistance

Herbicide resistance

Distill Into Digestible Units - Keep it simple. Discuss strengths and limitations (don’t create false equivalence)

Transgenic Traits May be Stacked into a Single Background

Cisgenics/Intragenics

Transfer of specific genes from the same species

Cis-genic = as-is

Intra-genic = all ‘native’ sequence with some re-arrangement

Cisgenics/Intragenics

Apple Scab

Traditional breeding introduced resistance gene from M. floribunda over 50 years.

Same sequence added by Dutch researchers in <5.

Gene Editing

CRISPR (clustered regularly interspaced short pallindromic repeats)

Targeted, few collateral effects

Allows production of custom mutations

Reasonably fast and efficient

No foreign genes present

GE vs. Traditional Breeding

Wide crosses exchange hundreds or thousands of genes and gene variants; GE moves only one/few.

Traditional breeding frequently uses plants that could never normally cross, GE uses genes from self or any other organism

GE can monitor the effect of a specific change; breeding seeks to judge the effect on plant productivity and does not address possible effects on individual genes.

Talking to public audiences

Plant genetic improvement techniques are safe.

All methods involve some small risk– but all are about the same risk as traditional breeding.

Techniques that breed in traits can take a long time

Directed changes are more precise and more rapidly available, but frequently require regulatory hurdles

Farmers

The Needy

Environment

Consumers

Talking to public audiences

We need to celebrate that we have the safest and most abundant food supply in human history- and expand plant genetic improvement techniques to serve the farmer, the needy, the environment and the consumer.

Thank you

kfolta.blogspot.com@kevinfolta

[email protected]