|JEON, AE RIN - Dankook University|
|KANG, JUN WON - University Of Washington|
|MOCK, RAYMOND - Retired ARS Employee|
Submitted to: Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/26/2014
Publication Date: 4/1/2014
Citation: Cheong, E.J., Jeon, A., Kang, J., Mock, R., Li, R. 2014. Elimination of black raspberry necrosis virus and blackberry yellow vein associated virus from Rubus spp. by in vitro axillary bud culture and thermotherapy. Horticultural Science. https://doi.org/10.17221/266/2013-HORTSCI.
Interpretive Summary: Many viruses including Black raspberry necrosis virus (BRNV) and Blackberry yellow vein associated virus (BYVaV) infect raspberries and blackberries (Rubus species), causing significant yield and quality losses. These viruses can be easily spread because these crops are usually propagated and distributed as vegetative cuttings. Therefore, the viruses must be eradicated from imported germplasm before it is distributed. In this study, a procedure combining tissue culture and heat treatment on axillary buds of raspberries and blackberries was developed to eliminate the two viruses from infected plants. Axillary buds from infected plants were grown aseptically at elevated temperatures (29°C/38°C) for 1-5 weeks, and new shoots were tested for virus infection. The treated plantlets were transferred to a growth chamber to recover, and then to a greenhouse for 5 months where they were tested for virus infection. Results showed that the method eliminated BRNV and BYVaV from infected Rubus spp., although with much greater efficiency for the former. This simple and time efficient protocol will be especially useful to produce virus-free mother plants in quarantine and certification programs. This will facilitate the safe exchange and distribution of Rubus species and help broaden the gene pool from which breeders can develop new and improved varieties.
Technical Abstract: Black raspberry necrosis virus (BRNV) and Blackberry yellow vein associated virus (BYVaV) are two of the most important viral pathogens of Rubus spp. In this study, a procedure combining in vitro culture and heat on axillary buds of Rubus spp. (R. occidentalis and R. fruticosus) was developed to eliminate BRNV and BYVaV from infected plants. Axillary buds were grown aseptically at 4-hr alternating periods of 29°C and 38°C with 14-hr day length for 1-5 weeks. Shoots induced after thermotherapy were tested for the viruses by RT-PCR. BRNV was not detected in any shoots, but BYVaV was still present in two thirds of the shoots, indicating that BRNV was heat labile whereas BYVaV was more heat tolerant. BRNV-free shoots were rooted in vitro and acclimatized in greenhouse. Regenerated plants remained virus-free after 2-month acclimatization, 3-month dormancy and 5-month growth periods. This protocol eliminated BRNV and BYVaV, although with much greater efficiency for the former.