Winter 2012 Newsletter

Scientists Develop Plan for Future Research

Rutgers University was the site of the third annual meeting of the Hybrid Hazelnut Consortium, a group of leading hazelnut researchers involved in a combined effort that will expedite development of disease-resistant, climatically adaptable hazelnut cultivars.

Scientists from Rutgers, Oregon State University, the University of Nebraska-Lincoln and Arbor Day Foundation met to assess their progress and to develop a road map for continued research as they prepare to apply for further funding.

The partners have made significant advances in the past two years toward their goal of creating hybrid hazelnuts that would be commercially viable throughout much of North America, including sequencing the genome of the disease that kills hazelnut plants, and developing a test that significantly reduces the time it takes to determine whether a plant is resistant.

Rutgers Scientists Detail Sequencing of the Anisogramma anomala Genome

Anisogramma anomala is the filamentous fungus that causes eastern filbert blight (EFB), the disease that is limiting the production of hazelnuts in most parts of the country. At the annual meeting, Rutgers’ Dr. Brad Hillman and Dr. Guohong Cai presented an in-depth look at their work on sequencing the genome of A. anomala and its value to the Consortium’s work to create disease-resistant hazelnuts.

EFB presents as cankers on hazelnut branches. It is first visible in the spring and is mature by fall, but the infection process is complex and can take up to 18 months between initial infection and symptoms. Severe cankering is followed by branch dieback and death of most European hazelnut plants.

A. anomala is a particularly difficult fungus to work with because it doesn’t grow well outside of infected plants. Dr. Cai isolated fungus DNA from a two-month-old sample and analyzed it using an Illumina sequencer. The massive amount of sequence data was assembled using a short-read assembly method called SOAPdenovo, and the assembled sequence was analyzed to develop simple sequence repeat (SSR, also called microsatellite) gene markers for the fungus. The genome of A. anomala was found to be surprisingly large, and 85% of it was repetitive DNA typical of transposable genetic elements.

Next Steps

Drs. Hillman and Cai will sequence the A. anomala genome in greater depth to obtain a better genome assembly as a platform for future work. They will also complete draft sequences of additional strains of A. anomala from different populations around the country and will combine this information with experimental screening of microsatellite loci.

Why Sequencing is Important

Understanding the genetic sequence of A. anomala will allow Consortium scientists to determine which plants contain useful genetic resistance, whether various fungal strains affect plants differently, and whether environment may play a part in resistance and/or disease progression. This will help determine which parent plants the Consortium should use to breed, how likely EFB is to change over time, and how that would affect host resistance.

The fact that A. anomala is an unusual, nearly endophytic, exclusively teleomorphic (sexual) ascomycete pathogen of a woody host makes the large and complex genome of this fungus an interesting subject of study in its own right.

Consortium Publishes Advances in Research

Below are links to some of the articles and presentations made by Consortium scientists in 2011. For a comprehensive list, see the Hybrid Hazelnut Consortium website.

• Kahn, P.C., T.J. Molnar, G. Zhang., and C.R. Funk. 2011. Investing in Perennial Crops to Sustainably Feed the World. Issues in Science and Technology. Summer 2011, p. 75-81
• Molnar, T. and N. Zhang. 2011. Application of a real-time PCR assay for detection of eastern filbert blight in hazelnut breeding. Abstracts of the Annual meeting of the American Phytopathological Society, Honolulu, HI August 6-10, 2011. Phytopathology Vol. 101, No. 6 (Supplement) S123
• G. Cai, C. Leadbetter, T. Molnar, and B.I. Hillman. 2011. Genome sequencing and analysis of Anisogramma anomala, the causal agent of eastern filbert blight. Abstracts of the Annual meeting of the American Phytopathological Society, Honolulu, HI August 6-10, 2011. Phytopathology Vol. 101, No. 6 (Supplement) S25 G. Cai, C. Leadbetter, T. Molnar, and B.I. Hillman. 2011.
• G. Cai, C. Leadbetter, T. Molnar, and B.I. Hillman. 2011. Genome-wide identification and characterization of microsatellite markers in Anisogramma anomala. Abstracts of the Annual meeting of the American Phytopathological Society, Honolulu, HI August 6-10, 2011. Phytopathology Vol. 101, No. 6 (Supplement) S25
• Molnar, T.J., Capik, J., Leadbetter, C.W., Zhang, Z., Cai, G. and B. Hillman. 2011. Developing hazelnuts (Corylus spp.) with durable resistance to eastern filbert blight caused by Anisogramma anomala. Abstracts of the Fourth International Workshop on the Genetics of Host-Parasite Interactions in Forestry. Pg. 39 Eugene, Oregon, USA. July 31-Aug. 5, 2011
• Molnar, T.J. and J. Capik. 2011. Utilization of Wild Corylus in the Genetic Improvement of Hazelnut. Abstracts of the 1st International Symposium of Wild Relatives of subtropical and Temperate Fruit and Nut Crops. Davis, Calif. March 19-23, 2011. p. 14-15
• Molnar, T.J. and J. Capik. 2011. Breeding for eastern filbert blight resistance in hazelnuts. HortScience 46(9):S8. (Abstr.)
• Capik, J. and T.J. Molnar. 2011. Breeding ornamental hazelnuts. HortScience 46(9):S3. (Abstr.)
• Leadbetter, C., T. Molnar and J. Capik. 2011. Screening new hazelnut germplasm for resistance to eastern filbert blight. HortScience 46(9):S4. (Abstr.)
• Mehlenbacher, S.A., D.C. Smith and R.L. McCluskey. 2011. Jefferson hazelnut. HortScience April 2011 46:662-664.
• Mehlenbacher, S.A., D.C. Smith, R.L. McCluskey and M.M. Thompson. 2011. ‘Tonda Pacifica’ hazelnut. HortScience March 2011 46:505-508.
• Sathuvalli, V.R. 2011. Eastern filbert blight in hazelnut (Corylus avellana): Identification of new resistance sources and high resolution genetic and physical mapping of a resistance gene. PhD dissertation. Oregon State University, Corvallis, Oregon.
• Sathuvalli, V.R. and S.A. Mehlenbacher. 2011. Characterization of American hazelnut (Corylus americana) accessions and Corylus americana x Corylus avellana hybrids using microsatellite markers. Genetic Resources and Crop Evolution DOI 10.1007/s10722-011-9743-0.
• Chambers, U., V.M. Walton, and S.A. Mehlenbacher. 2011. Susceptibility of hazelnut cultivars to filbertworm, Cydia latiferreana. Amer. Soc. Hort. Sci. October 2011 vol.46 no. 10 1377-1380.
• Sathuvalli, V. S.A. Mehlenbacher and D.C. Smith. 2011. DNA markers linked to eastern filbert blight resistance from a hazelnut selection from the Republic of Georgia. J. Amer. Soc. Hort. Sci. 136: 350-357.