Confirmation of the elimination of <i>Apple stem grooving virus</i> from apple trees by <i>in vitro</i> chemotherapy

Abstract

Apple stem grooving virus (ASGV) is widespread in its distribution in apple trees. The virus causes tree decline and graft union necrosis in certain combinations of scion and rootstock, and attempts are made usually to control the virus where apples are grown commercially. ASGV is difficult if not impossible to eliminate by heat therapy. In 1996, in vitro cultures of apple infected with ASGV were grown for 9-12 weeks on media containing quercetin and ribavirin (10 μg/mL of each), then cultured on media free of these chemicals. Analysis by immunocapture (IC) RT-PCR failed to detect the presence of ASGV, while all untreated controls were positive. Treated and untreated cultures were subcloned, rooted, hardened, and eventually planted in the field. The plants were observed and tested annually by IC/RT-PCR from 1998 - 2008. The treated plants were consistently negative by IC/RT-PCR, while untreated plants tested positive for ASGV. After 11 years of testing by the sensitive IC/RT-PCR assay it is safe to say that in vitro chemotherapy with quercetin and ribavirin is effective for the elimination of ASGV from apple.

Keywords: Apple stem grooving virus, in vitro chemotherapy, quercetin, ribavirin, immunocapture RT-PCR