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ARS Home » Northeast Area » Geneva, New York » Plant Genetic Resources Unit (PGRU) » Research » Research Project #434954

Research Project: Development of Biotic and Abiotic Stress Tolerance in Apple Rootstocks

Location: Plant Genetic Resources Unit (PGRU)

2022 Annual Report

1. New method of virus elimination for apple rootstocks. The Geneva apple rootstock breeding program has adopted a procedure to establish “clean” propagation material at key micropropagation laboratories prior to release of elite breeding lines into the commercial stream as rootstock cultivars. In preparation to release a set of new apple rootstocks for the U.S. industry, we collaborated with Foundation Plant Services in Davis, California, and APHIS PGQP in Beltsville, Maryland, to index plant material with what is known as High Throughput Sequencing (HTS) or Deep Sequencing, which is extremely powerful at picking up even small quantities of viral RNA. We found that some of the stocks slated for release to the public were infected by viruses. At the same time, scientists at USDA ARS National Laboratory for Genetic Resources Preservation (NLGRP), were working on discovering new ways to eradicate viruses from apple germplasm destined for cryopreservation. As a result, a collaboration ensued between the Geneva breeding program and NLGRP to investigate whether thermotherapy or cryotherapy alone or in combination could effectively eradicate apple viruses from in-vitro cultures of the apple rootstocks destined for release. Overall, thermotherapy combined with cryotherapy treatments resulted in the highest percentage of virus- and viroid-free plants.

Review Publications
Bettoni, J.C., Fazio, G., Carvalho Costa, L., Hurtado-Gonzales, O.P., Ah Rwahnih, M., Nedrow, A.K., Volk, G.M. 2022. Thermotherapy followed by shoot tip cryotherapy eradicates latent viruses and Apple hammerhead viroid from in vitro apple rootstocks. Plants. 11(5). Article e582.
Liu, J., Abdelfattah, A., Wasserman, B., Wisniewski, M., Droby, S., Fazio, G., Mazzola, M., Wu, X. 2022. Contrasting effects of genotype and root size on the fungal and bacterial communities associated with apple rootstocks. Horticulture Research. 9. Article uhab013.