Title
Thermotherapy Followed by Shoot Tip Cryotherapy Eradicates Latent Viruses and Apple Hammerhead Viroid from In Vitro Apple Rootstocks
Date Issued
01 March 2022
Access level
open access
Resource Type
journal article
Author(s)
USDA-APHIS Plant Germplasm Quarantine Program
Publisher(s)
MDPI
Abstract
Virus and viroid-free apple rootstocks are necessary for large-scale nursery propagation of apple (Malus domestica) trees. Apple stem grooving virus (ASGV) and Apple chlorotic leaf spot virus (ACLSV) are among the most serious apple viruses that are prevalent in most apple growing regions. In addition to these viruses, a new infectious agent named Apple hammerhead viroid (AHVd) has been identified. We investigated whether thermotherapy or cryotherapy alone or a combination of both could effectively eradicate ACLSV, ASGV, and AHVd from in vitro cultures of four apple rootstocks developed in the Cornell-Geneva apple rootstock breeding program (CG 2034, CG 4213, CG 5257, and CG 6006). For thermotherapy treatments, in vitro plants were treated for four weeks at 36° C (day) and 32° C (night). Plant vitrification solution 2 (PVS2) and cryotherapy treatments included a shoot tip preculture in 2 M glycerol + 0.8 M sucrose for one day followed by exposure to PVS2 for 60 or 75 min at 22° C, either without or with liquid nitrogen (LN, cryotherapy) exposure. Combinations of thermotherapy and PVS2/cryotherapy treatments were also performed. Following treatments, shoot tips were warmed, recovered on growth medium, transferred to the greenhouse, grown, placed in dormancy inducing conditions, and then grown again prior to sampling leaves for the presence of viruses and viroids. Overall, thermotherapy combined with cryotherapy treatment resulted in the highest percentage of virus-and viroid-free plants, suggesting great potential for producing virus-and viroid-free planting materials for the apple industry. Furthermore, it could also be a valuable tool to support the global exchange of apple germplasm.
Volume
11
Issue
5
Language
English
OCDE Knowledge area
CrÃas y mascotas
PesquerÃa
Subjects
Scopus EID
2-s2.0-85125299508
Source
Plants
ISSN of the container
22237747
Sponsor(s)
Funding: This research was funded in part by USDA-ARS.
USDA is an equal opportunity employer and provider. Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the US Department of Agriculture. Thanks to Vincent Bus and Satish Kumar from Plant & Food Research, Hawke?s Bay, New Zealand, for providing internal reviews of the manuscript.
Sources of information:
Directorio de Producción CientÃfica
Scopus