Author
Martin, Robert | |
Keller, Karen | |
MATHEWS, H - EXELIXIS PLANT SCIENCES |
Submitted to: Acta Horticulturae
Publication Type: Proceedings Publication Acceptance Date: 5/18/2004 Publication Date: 9/25/2004 Citation: Martin, R.R., Keller, K.E., Mathews, H. 2004. Development of resistance to raspberry bushy dwarf virus in 'meeker' red raspberry. Acta Horticulturae. 656:186-191. Interpretive Summary: Over the last 15 years, raspberry bushy dwarf virus (RBDV) has been a reemerging problem throughout raspberry growing regions of the world. This is primarily due to growers planting susceptible cultivars that have superior fruit quality. Crumbly fruit and yield reduction can combine to reduce crop value by more than 50%. Raspberry bushy dwarf virus is pollen-borne, making chemical control virtually impossible. 'Meeker' raspberry plants were transformed with the coat protein gene, mutated forms of the movement protein gene or nontranslatable RNA of RBDV. The presence of these viral sequences was confirmed by DNA hybridization analysis and RT-PCR of DNAse digested total RNA preparations. Of 197 transgenic lines planted in replicated blocks in the field under extreme disease pressure, five lines remained free of RBDV after four years. All 202 of the wild-type 'Meeker' plants in the same plot were infected with RBDV at the end of four years. Most transgenic lines had 9 of 9 plants infected and a few lines showed partial resistance to infection, with 1 to 6 of the 9 plants infected. The five lines showing field resistance were also resistant to RBDV when tested by grafting. Fruit evaluations of these five lines showed that they contained the five anthocyanins at the same relative concentrations as were present in wild type 'Meeker' fruit. Field and fruit evaluations of these five lines will be continued for another two years. Technical Abstract: Over the last 15 years, raspberry bushy dwarf virus (RBDV) has become an important problem throughout raspberry growing regions of the world. Crumbly fruit and yield reduction can combine to reduce crop value by more than 50%. Raspberry bushy dwarf virus is pollen-borne, making chemical control virtually impossible. 'Meeker' raspberry plants were transformed with the coat protein gene or mutated forms of the movement protein gene of RBDV. The presence of these viral genes was confirmed by DNA hybridization analysis and RT-PCR of DNAse digested total RNA preparations. Of 197 transgenic lines planted in replicated blocks in the field under extreme disease pressure, 5 lines remained free of RBDV after four years; all 202 of the wild-type 'Meeker' plants in the same plot were infected. Most transgenic lines had 9 of 9 plants infected, and a few lines showed partial resistance to infection, with 1 to 6 of 9 plants infected. The 5 lines showing field resistance were also resistant to RBDV when tested by grafting. Fruit evaluations of these 5 lines showed that they contained 5 anthocyanins at the same concentrations as were present in wild type 'Meeker' fruit. |