SAVING THE AMERICAN CHESTNUT AND BUTTERNUT TREE

1. SAVING THE AMERICAN CHESTNUT AND BUTTERNUT TREE TRISTATE FOREST STEWARDSHIP CONFERENCE March 8, 2008 Larry R. Severeid

3. NATURAL RANGE OF CHESTNUT AND BUTTERNUT

6. THE MIGHTY CHESTNUT

13. THE CHESTNUT CANKER

23. THE �WHITE WALNUT�

25. BUTTERNUT CANKER

29. STRATEGIES FOR RESTORING THE CHESTNUT Breeding with surviving American chestnut populations. Hybridization with Asian chestnuts. (early programs) Backcross Breeding Program (American Chestnut Foundation) Transgenic Manipulation Introduction of hypovirulent fungi (Hypovirulence)

30. BACKCROSS STRATEGY(THE AMERICAN CHESTNUT FOUNDATION) In 1982, the foundation was established because of a vision of two men, Charles Burnham, a noted geneticist, and Phil Rutter, an evolutionary ecologist. They were sure that the American chestnut could be restored. These Minnesotans were convinced that the American chestnut could be saved by applying the same principles that had been successful in breeding plants. This method, back crossing, was used to transfer a single hereditary trait among interbreeding species. The desired trait was blight resistance and the species were the American chestnut and the blight resistant Asian chestnuts. The big difference was the time scale. To achieve their desired objective, it could take over 25 years. What institution would have that kind of attention span? They concluded that only a private, self funded foundation would remain focused and stead-fast in achieving such an objective. A board (primarily mid-westerners) was assembled and in 1983 they first met. The first foundation meeting was on September 22, 1984. The rest is history and the Foundation presently has 7000 members. There are 15 state chapters, University, State, and Federal affiliates. A research center was established in Virginia in 1989 and has remained the prime coordinator of the reseach activities, especially the back cross program.

34. BC3 F2 ORCHARD

35. TRANSGENIC APPROACH The ideal transgenic transfer would be to identify and isolate the 3 genes of resistance from the Asian chestnuts and insert them into the American chestnut. These genes have not yet been isolated but research centers are working to isolate them. Presently, scientists are testing a gene obtained from wheat, that is also found in many grasses. This gene produces (encodes) an enzyme, oxalic oxidase, that breaks down oxalic acid (oxalate). The blight fungus produces oxalic acid along the margin of the canker, disrupting the trees defenses. There is early evidence that this introduced gene enhances the trees ability to resist the progression of the fungus. Finally, genes isolated from viruses that cause hypovirulence in the fungus are being transferred into the nucleus of the fungus, expanding the effectiveness of this control mechanism.

36. HYPOVIRULENCE APPROACH There are three viruses that have been identified that infect and weaken the chestnut blight fungus. Those chestnut trees infected with the hypovirulent fungi are able to contain the cankers and eventually eliminate the infection. In Europe, the European chestnuts were saved when the cryphonectria strains became infected by a virus and blight fungi were rendered too weak to destroy the trees. The infected trees recovered. In America, hypovirulent fungi are being studied. The results have not been as successful as in Europe, since we have too many strains that are not �compatible� and the infection is not able to effectively spread. Transgenic manipulation may aid in widening the effectiveness of this method of control if the infection can be spread during sexual reproduction by inserting the virus into the nucleus.

38. STRATEGIES FOR SAVING THE BUTTERNUT

39. THE DARK BARK BUTTERNUT

45. THE ROCKLANDBUTTERNUT AND CHESTNUT CLONE ORCHARD

52. CLOSING THOUGHTS The movement of some plants from one continent to another has resulted in catastrophic consequences. Many of the plants have became uncontrollably invasive because there are no local environmental checks. Examples: Buckthorn, garlic mustard, honeysuckle, and reed canary grass. More catastrophic has been the transmission of pathogens from plants that are blight resistant to vulnerable plants that have no resistance. Examples: Emerald ash bore-(ash trees), and Cryphonectria - Chestnut tree. We cannot change the results of evolution, but we can use all of the resources available to control these invasive plants and save our vulnerable plants. IT WILL BE NECESSARY THAT WE LAND OWNERS ASSIST IN THIS CHALLENGE.