Shoot tip cryotherapy for plant pathogen eradication

Authors: WANG, M-R - Northwest A&f University; BI, W-L - University Of Guelph; BETTONI, J - Plant And Food Research; ZHANG, D - Northwest A&f University; Volk, Gayle; WANG, Q-C - Northwest A&f University

Submitted to: Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/29/2022
Publication Date: 4/6/2022
Citation: Wang, M., Bi, W., Bettoni, J.C., Zhang, D., Volk, G.M., Wang, Q. 2022. Shoot tip cryotherapy for plant pathogen eradication. Plant Pathology. 71(6):1241-1254. https://doi.org/10.1111/ppa.13565.
DOI: https://doi.org/10.1111/ppa.13565

Interpretive Summary: Plant pathogens are serious threats to agricultural production worldwide. Pathogens in vegetatively propagated materials are particularly problematic because they are difficult to remove from living plants and can be transferred to new plants that are produced by grafting or cuttings. Shoot tip cryotherapy is a technique that is based on shoot tip cryopreservation technologies. Most frequently, shoot tips are excised from pathogen-infected tissue culture plants and then treated with cryoprotectants and exposed to liquid nitrogen. The shoot tips are then grown in tissue culture and tested for the presence of pathogens, and a certain percentage of the plants are found to be have the pathogens eradicated. This is because many pathogens (particularly viruses) are limited to the phloem and don't invade plant shoot tips. Traditional shoot-tip excision methods require the excision of meristems that do not have associated phloem tissue, and this is very difficult. Shoot tip cryotherapy makes use of larger (1-2 mm shoot tips), and the phloem tissues that harbor the pathogens are killed during exposure to liquid nitrogen, and only non-infected cells grow into the resulting plants. In some cases, cryotherapy methods are more effective when combined with thermotherapy or chemotherapy treatments. This manuscript lists pathogens that have been successfully removed from plants using cryotherapy methods. It also provides information about key variables and procedural steps for implementation of the method.

Technical Abstract: Diseases caused by plant pathogens such as viruses, viroids and phytoplasmas cause huge economical losses of agricultural production and limit the safe movement of plant materials across borders. The use of pathogen-free planting materials provides a strategy for efficient management of these diseases and facilitates the global exchange of genetic resources. Shoot tip cryotherapy is a novel biotechnology method that uses cryogenic procedures to eradicate plant pathogens from the diseased plants. Combining thermotherapy or chemotherapy with shoot tip cryotherapy has further enhanced pathogen eradication efficiency. This review provides updated and comprehensive information on shoot tip cryotherapy and the combination of thermotherapy or chemotherapy with shoot tip cryotherapy for pathogen eradication. Prospects are proposed for future studies.