Our forests are facing many challenges Chestnut Blight How a single - - PowerPoint PPT Presentation

Our forests are facing many challenges Chestnut Blight

How a single gene may help save the American Chestnut

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Many undergrads, high school students, collaborators, and many volunteers… Current research team: Bill Powell (Director) Chuck Maynard (Co-Director Emeritus) Linda McGuigan (TC lab Manager) Allison Oakes (Post doctoral fellow) Kaitlin Breda (Admin assistant) Andrew Teller (Research Analyst) Andy Newhouse (PhD grad student) Tyler Desmarais (MS grad student) Dakota Matthews (MS grad student) Vern Coffey (MS grad student) Yoks Bathula (MS grad student) Xueqing Xiong (MS grad student) Erik Carlson (MS grad student) Hannah Pilkey (MS grad student)

The work of well over 100 people over the years

Agricultural Wood products

Chestnuts roasting on an

• pen fire, 
The Christmas

Song (by Torme and Wells in 1946)

Social/historical

Keystone forest species (environmental benefits)

Restoration of the American chestnut may benefit many endangered species

Carolina northern flying squirrel (Glaucomys sabrinus) Small Whorled Pogonia, Isotria medeoloides, Habitat promoted by American chestnut

American chestnut was predominant before these species were endangered

American burying beetle More mast, more rodents, supports

Forest History Society

American chestnut tree had diverse forms

photo in MI, 1980s by Alan D. Hart

Chestnut blight in the U.S.

In 1904, discovery

• f chestnut

blight in the Bronx Zoo (Merkel)

~50 years spread through natural range killing ~4 billion American chestnut trees Allegheny Chinkapin, C. pumila var. pumila Ozark Chinquapin, C. pumila var. ozarkensis

Chestnut blight on related species: Chestnut blight also survives on oaks

Spring 1912

1912 photo of blight in NY

After over a century of unsuccessful attempts at combating the blight, what are the choices for restoration?

Chestnut f1 hybrids are OK for ornamentals or crops, Not for restoration

American chestnut

• C. dentata

European chestnut

• C. sativa

Chinese chestnut

• C. mollissima

Japanese chestnut

• C. crenata

Are hybrids suitable for restoration?

Lion: Panthera leo Tiger: Panthera tigris Liger: Panthera hybrid American chestnut Castanea dentata (canopy tree) Chinese chestnut Castanea mollissima (orchard tree)

Unlikely to replace the American chestnut

Better ways:

TACF Meadowview Farm, VA

• Dr. Fred Hebard

(started 1983)

• Dr. Jared Westbrook

(current)

Goal is for 1/16 Chinese chestnut genome to contain the required 3 to 6 more blight resistance loci (#genes?)

~38,000 CC genes + ~38,000 AC genes

Unwanted traits Unwanted traits Unwanted traits What if you didn’t have to select out any unwanted traits?

1/16 Chinese chestnut genes:

10 pages or 2,375 words It was very exciting at

that season to roam the then boundless chestnut woods of Lincoln, …

Henry David Thoreau, “Walden: or Life in the Woods,” 1899

Making very small changes, adding

• nly 2 words

CC AC

Breeding & Transgenics:

(Both viable options & both have advantages & disadvantages)

Chestnut has ~ 38,000 gene pairs

blight resistant

100% American chestnut + blight resistance

What genes do we test?

Forest Health Initiative grant: Asian species Quantitative resistance, therefore requires multiple genes: Possibilities so far out of 28 being tested:

• 1. Acid phosphatase (C. mollissima)
• 2. Laccase-like protein (C. mollissima)
• 3. Lipid transfer protein (C. mollissima)
• 4. Cystatin (C. mollissima)
• 5. Glutathione s-transferase (C. mollissima)
• 6. Deoxy-arabino-heptulosonate phosphate synthase (C. mollissima)
• 7. Subtilisin-like protease (C. seguinii)

Or other plants?

stilbene synthase (grape) – phytoalexins like resveratrol

(Dr. Joe Nairn, UGA)

• xalate oxidase (wheat and many other plants)

(Dr. Randy Allen, Texas Tech)

Remember, it is not the source of the gene that is important, it is the function of the gene that is key.

Oxalate oxidase (OxO) from wheat

ubiquitous enzyme in many plants & fungi

(non-gluten enzyme)

Wheat Rice Barley Sorghum Banana Oil palm Date palm Barrel clover Strawberry Beet Cacao Peanut Peach & Apricot Goatgrass Stiff brome Wild einkorn Perennial ryegrass Castor bean Insulin plant Spiny amaranth Azalea Mosses (6 spp.) Fungi

Not a pesticide (more like an antitoxin) Does not kill the fungus, no ‘cidal’ activity.

Detoxifies oxalate (oxalic acid)

Since the fungus survives, less selective pressure to overcome the oxalate oxidase.

Oxalate oxidase (OxO) from wheat

ubiquitous enzyme in many plants & fungi

(non-gluten enzyme)

On transgenic American chestnut, changes the fungal lifestyle from a pathogen to a saprophyte (coexist). (like on Chinese chestnut & some oaks)

How do we get the gene in? How do we test for blight resistance?

Coexistence of

• C. parasitica and chestnut trees

Therefore, the tree tolerates the fungus The fungus survives on American chestnut similar to Chinese chestnut

Inheritance of blight tolerance

Pollination with transgenic pollen

Darling 311 T1 Seedling OxO Transgenic American Chestnut Full Sibling Control Non-Transgenic American Chestnut

Photographed 13 weeks after inoculation with C. parasitica strain EP155

Federal regulatory review:

Non-regulated status Voluntary - No further questions Registration?

New paradigm for regulators

Many typical comparative studies, plus additional experiments for restoration trees

(slide by Andy Newhouse)

A unique opportunity with the Darling lines of blight resistant American chestnut:

Rescuing the surviving genetic diversity.

18 in. DBH American chestnut Manlius, NY

Unique feature of the ‘Darling’ American chestnut trees:

Rescuing genotypes surviving trees

Transgenic American chestnut TACF conservation orchards Or surviving wild population

Or backcross trees

pollen Regionally adapted Continue to maximize

• ut-crossing

Allows: Allelic rescue, local adaptation, and increases genetic diversity

T1 Genotypes ½ mother & ½ father

Parental allelic composition

Offspring 50% OxO & fully blight resistance seed

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Supplier of pollen

Pest or Pathogen destroys the trees

Applications to forest health Need to take a holistic approach

Early development of pest & pathogen resistant trees for restoration Containment procedures buying time Rescue genetic diversity

Genetic engineering & breeding

Questions?

"We humans are more than consumers, we have gifts of our own to give to the earth."

• Dr. Kimmerer at the U.N.