Virus assessment of Ajuga reptans cultivars reveals alfalfa mosaic, tobacco streak, and cucumber mosaic (CMV) viruses, and a CMV satellite RNA.
Ajuga reptans is an herbaceous ornamental mint grown in borders or as a groundcover, and is commonly propagated vegetatively and by seed. A total of 356 A. reptans samples were obtained from growers in Washington, Michigan, Iowa, and Ohio, USA, and screened for alfalfa mosaic virus (AMV), tobacco streak virus (TSV), cucumber mosaic virus (CMV), tomato aspermy virus (TAV), tomato spotted wilt virus (TSWV), impatiens necrotic spot virus (INSV), tobacco mosaic virus (TMV), potato virus X (PVX), and 80 potyviruses, using direct antibody sandwich (DAS) and indirect ELISA. Viral-associated double-stranded ribonucleic acid (dsRNA) analysis was used to detect an apparent satellite (sat) RNA, and northern hybridization using a digoxigenin (DIG) labelled (S) CARNA-5 cDNA probe was used to confirm the identity of the apparent satRNA. No incidences of TAV, TMV, TSWV, INSV, PVX, or potyviruses were detected. CMV was detected in 11%, AMV in 22.2%, TSV in 3.7%, and mixed infections of CMV and AMV in 1.1% of the samples. SatRNA was detected in 36 A. reptans cv. Royalty, 2 Rainbow, and 2 Burgundy Glow samples by dsRNA analysis, and confirmed by hybridization in 29 Royalty and 1 Burgundy Glow samples. Sixteen A. reptans cv. Royalty seedlings grown from seed harvested from CMV-infected plants were tested by ELISA for CMV, AMV, and TSV. All were positive for CMV, and 2 were positive for a mixed infection of CMV and AMV. SatRNA was detected in all 16 seedlings by RT-PCR.