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Title:   Author  item
                                            Kluepfel, Danielitem
                                            McClean, Aliitem
                                            Aradhya, Mallikarjunaitem
                                            Moersfelder, Jeff
  Submitted to: Acta Horticulturae
                                    Publication Type: Peer Reviewed Journal
                                    Publication Acceptance Date: 3/1/2015
                                    Publication  Date: 3/25/2015
                                    Publication URL: http://actahort.org/books/1074/Citation: Kluepfel, D.A., Mcclean, A.E., Aradhya, M.K., Moersfelder, J.W. 2015. Identification of Juglans wild relatives resistant to crown gall caused by Agrobacterium tumefaciens. Acta Horticulturae. 1074:87-94.Interpretive Summary:
                                Technical Abstract: Wild species are a source of useful agronomic traits for crop plants including but not limited to pathogen resistance, drought tolerance, and salt tolerance (Aradhya and Kluepfel 2012).  To exploit this natural diversity of disease resistance, we are conducting the first systematic exploration of the wild species Juglans germplasm collection for resistance to crown gall caused by A. tumefaciens. (http://rootstocks.net/).   In preliminary screens, we examined approximately 2,000 open pollinated (OP) progeny from 328 mother trees and discovered CG resistance in the progeny of J. hindsii, J. major, J. ailantifolia, J. mandshurica, J. microcarpa, and J. cathayensis. These Juglans spp. are now the major source of plant material used in our search for crown gall resistance. We also have identified OP seedlings from the Juglans sp. relative, Chinese Wingnut (Pterocarya sp.), which displayed a high and consistent level of crown gall and Phytophthora resistance.  
Several individual plant genotypes showing enhanced crown gall resistance were identified from several of the species described above.  These plants developed no to limited CG symptoms two months post-inoculation, and in some cases remained CG free six months post-inoculation.  We generated rooted cuttings from these promising CG resistant candidates.  Some of these clonal individuals continued to show only minor symptoms up to two years post inoculation.  The vast majority of these individual plants were derived from J. microcarpa and Pterocarya sp. seedlings.
Wild species are a source of useful agronomic traits for crop plants including but not limited to pathogen resistance, drought tolerance, and salt tolerance (Aradhya and Kluepfel 2012).  To exploit this natural diversity of disease resistance, we are conducting the first systematic exploration of the wild species Juglans germplasm collection for resistance to crown gall caused by A. tumefaciens. (http://rootstocks.net/).   In preliminary screens, we examined approximately 2,000 open pollinated (OP) progeny from 328 mother trees and discovered CG resistance in the progeny of J. hindsii, J. major, J. ailantifolia, J. mandshurica, J. microcarpa, and J. cathayensis. These Juglans spp. are now the major source of plant material used in our search for crown gall resistance. We also have identified OP seedlings from the Juglans sp. relative, Chinese Wingnut (Pterocarya sp.), which displayed a high and consistent level of crown gall and Phytophthora resistance.  
Several individual plant genotypes showing enhanced crown gall resistance were identified from several of the species described above.  These plants developed no to limited CG symptoms two months post-inoculation, and in some cases remained CG free six months post-inoculation.  We generated rooted cuttings from these promising CG resistant candidates.  Some of these clonal individuals continued to show only minor symptoms up to two years post inoculation.  The vast majority of these individual plants were derived from J. microcarpa and Pterocarya sp. seedlings.


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