|WANG, MIN-RUI - Colorado State University|
|HAMBORG, ZHIBO - Norwegian Institute Of Bioeconomy Research(NIBIO)|
|BLYSTAD, DAG-RAGNAR - Norwegian Institute Of Bioeconomy Research(NIBIO)|
|WANG, QIAO-CHUN - Northwest A&f University|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 7/1/2020
Publication Date: 12/1/2020
Citation: Wang, M-R., Hamborg, Z., Blystad, D., Volk, G.M., Wang, Q. 2020. A Story of ‘Fire and Ice’: Combining thermotherapy with cryotherapy for improved virus eradication - Case studies of Apple and Shallot. Cryobiology. 97:283. https://doi.org/10.1016/j.cryobiol.2020.10.132.
Interpretive Summary: N/A
Technical Abstract: Both thermotherapy and cryotherapy have been used to produce virus-free plants. We have combined these two therapies to improve virus eradication in the woody dicot apple (Malus spp.) and herbaceous monocot shallot (Alium cepa var. aggregatum) crops. Apple stem grooving virus (ASGV) is a virus that infects the apical meristem of apple ‘Gala’. To eradicate this virus, in vitro- grown ‘Gala’ plants were first treated with an alternating temperature regimen of 36 ' (day) and 32 ' (night). Then, shoot tips excised from 0-6 weeks of thermo-treated shoots were cryo-treated using a droplet-vitrification. Shoot tip regrowth levels decreased with increased durations of thermotherapy, and the virus-free frequency increased. Four weeks of thermotherapy followed by shoot-tip cryo-exposure resulted in ‘Gala’ plants with regrowth levels of 44%, of which 93% of the plants were free of ASGV. The optimized protocol was further applied to four other Malus spp., resulting in the ASGV eradication levels ranging from 30% to 100%. As for shallot, the in vitro shoots were thermo-treated at constant 36 ' for 0, 2 and 4 weeks, followed by a droplet-vitrification cryotherapy protocol in an attempt to eradicate onion yellow dwarf virus (OYDV) and shallot latent virus (SLV). The shoot tip regrowth levels of shallot were lower with extended thermotherapy durations. Four weeks of thermotherapy prior to cryotherapy improved the virus eradication from 5% (cryotherapy only) to 54%. Virus immunolocalization revealed that shoot tips of apple and shallot had significantly lower levels of virus after thermotherapy. Performing cryotherapy on plants with lowered virus titers resulted in higher levels of virus eradication. Therefore, the use of thermotherapy may increase the efficacy of cryotherapy to eradicate plant viruses.