Streamlining global germplasm exchange: Integrating scientific rigor and common sense to exclude phantom agents from regulation

Authors: TZANETAKIS, IOANNIS - University Of Arkansas; AKNADIBOSSIAN, VICKEN - University Of Florida; SPAK, JOSEF - Czech Academy Of Sciences; CONSTABLE, FIONA - Agriculture Victoria; HARPER, SCOTT - Washington State University; Hammond, John; CANDRESSE, THIERRY - University Of Bordeaux; VIDALAKIS, GEORGIOS - University Of California, Riverside; FREITAS-ASTUA, JULIANA - Embrapa; FUCHS, MARC - Cornell University; FOLIMONOVA, SVETLANA - University Of Florida; JELKMANN, WILHEM - Julius Kuhn Institute; MALIOKKA, VARVARA - Aristotle University Of Thessaloniki; MARAIS, ARMELLE - University Of Bordeaux; MARTIN, ROBERT - Oregon State University; Mollov, Dimitre

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/3/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary: The correct identification of the causal agents of plant diseases is necessary in order to select appropriate disease management methods. Accurate identification of the causal agents is also required to allow quarantine officials to generate appropriate regulations and testing procedures in order to protect against the introduction of diseases when plants are imported. However, there have been multiple examples of diseases described only by symptoms being regulated in the absence of identification of any causal agent. Current lists of regulated pathogens in various countries include several such ‘phantom’ agents, for which no reference materials are available for development of diagnostic procedures, thus impeding international exchange of valuable germplasm, which cannot be certified free of an unknown pathogen. A listing of diseases associated with ‘phantom’ pathogens of important clonally propagated fruit and ornamental crops is provided here as the basis for potential rationalization of quarantine restrictions on such unknown pathogens. This would aid international exchange of clean germplasm which can be certified free of known pathogens of concern.

Technical Abstract: Plant virology was established as a discipline in the late 19th century after the discovery of a novel entity causing tobacco mosaic disease described as ‘contagium vivum fluidum’ (Beijerinck, 1898). Since then, the field has undergone tremendous progress in understanding plant viruses and the diseases they cause. Accurate laboratory diagnostic tools, developed for the detection and identification of viruses and other systemic pathogens (e.g. viroids, phytoplasmas and fastidious bacteria) in plants, have advanced our understanding of pathogen-vector-host interactions and are regularly employed in the production of plants that are free from regulated pathogens. Clean plants are crucial for the sustainable production of clonally propagated crops (Gergerich et al. 2015; Hammond et al. 2023), facilitating the safe exchange of plant material globally and are often the basis of national or regional certification programs. Although accurate diagnostic tools are crucial for certification programs and for facilitating the safe exchange of plant material, current lists of regulated pathogens contain several 'phantom' agents, which impede access to that material.