Our forests are facing many challenges

Chestnut Blight How a single gene may help save the American Chestnut

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

The work of well over 100 people over the years

2 Wood products

Agricultural Social/historical

Chestnuts roasting on an open fire, The Christmas Song (by Torme and Wells in 1946) Keystone forest species (environmental benefits) Restoration of the American chestnut may benefit many endangered species

Carolina northern flying squirrel More mast, more rodents, supports (Glaucomys sabrinus) American burying beetle

Small Whorled Pogonia, Isotria medeoloides, Habitat promoted by American chestnut

American chestnut was predominant before these species were endangered American chestnut tree had diverse forms photo in MI, 1980s by Alan D. Hart

Forest History Society

Chestnut blight in the U.S.

Chestnut blight on related species: ~50 years spread through natural range Allegheny Chinkapin, C. pumila var. pumila killing ~4 billion American chestnut trees Ozark Chinquapin, C. pumila var. ozarkensis

In 1904, discovery of chestnut blight in the Bronx Zoo (Merkel)

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 Japanese chestnut C. crenata

American chestnut Chinese chestnut C. dentata C. mollissima

European chestnut C. sativa Are hybrids suitable for restoration? Unlikely to replace the American chestnut

Lion: Panthera leo Tiger: Panthera tigris

American chestnut Castanea dentata (canopy tree)

Chinese chestnut Castanea mollissima Liger: Panthera hybrid (orchard tree) Better ways: ~38,000 CC genes + ~38,000 AC genes Unwanted traits TACF Meadowview Farm, VA Dr. Fred Hebard (started 1983) Unwanted traits

Dr. Jared Westbrook (current) Unwanted traits

Goal is for 1/16 What if you Chinese chestnut didn’t have to genome to contain select out any the required 3 to 6 unwanted more blight traits? resistance loci (#genes?) Breeding & Transgenics: (Both viable options & both have advantages & disadvantages) Chestnut has ~ 38,000 gene pairs 1/16 Chinese chestnut genes:

CC AC

10 pages or 2,375 words It was very exciting at that season to roam the blight resistant then boundless chestnut Making very small woods of Lincoln, … changes, adding Henry David Thoreau, “Walden: or only 2 words Life in the Woods,” 1899 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) Remember, it is not the source of the gene that is important, it is the function of the gene that is key.

Or other plants? stilbene synthase (grape) – phytoalexins like resveratrol (Dr. Joe Nairn, UGA)

oxalate oxidase (wheat and many other plants) (Dr. Randy Allen, Texas Tech)

Oxalate oxidase (OxO) from wheat ubiquitous enzyme in many plants & fungi (non-gluten enzyme)

Wheat Rice Goatgrass Barley Stiff brome Sorghum Wild einkorn Banana Perennial ryegrass Oil palm Castor bean Date palm Insulin plant Barrel clover Spiny amaranth Strawberry Beet Azalea Cacao Mosses (6 spp.) Fungi Peanut Peach & Apricot Oxalate oxidase (OxO) from wheat ubiquitous enzyme in many plants & fungi (non-gluten enzyme) Detoxifies oxalate (oxalic acid)

Not a pesticide (more like an antitoxin)

Does not kill the fungus, no ‘cidal’ activity. Since the fungus survives, less selective pressure to overcome the oxalate oxidase. 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 Full Sibling Control OxO Transgenic American Non-Transgenic American Chestnut Chestnut

Photographed 13 weeks after inoculation with C. parasitica strain EP155 Federal regulatory review: Voluntary - Registration? Non-regulated status No further questions

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 Supplier of pollen T1 Genotypes Regionally ½ mother & ½ father adapted

Parental allelic pollen seed composition Continue to maximize out-crossing

Allows: Transgenic Allelic rescue, American local adaptation, chestnut and increases genetic diversity TACF conservation orchards Offspring Or surviving wild population 50% OxO & fully blight resistance

Or backcross trees 26

Applications to forest health Need to take a holistic approach Pest or Pathogen destroys the trees

Containment procedures buying time

Rescue genetic Genetic engineering diversity & breeding

Early development of pest & pathogen resistant trees for restoration "We humans are more than consumers, we have gifts of our own to give to the earth." Dr. Kimmerer at the U.N.

Questions?