First Report of Banana Streak Virus Infecting Bananas (Musa spp.) in Georgia, U.S.A.

Abstract

Banana streak virus (BSV) is a badnavirus containing a circular dsDNA genome of 7.4 kb that causes a viral leaf streak disease of banana (Musa spp.) worldwide (Dallot et al. 2001). On bananas, typical symptoms of BSV include broken or continuous chlorotic streaks or spindle-shaped patterns that are first chlorotic, become increasingly dark in color, and subsequently result in black streaking in older leaves (Dallot et al. 2001). In the summer of 2019, six symptomatic leaves from three different plants were collected from the University of Georgia Banana Research Plot, Tifton, GA. The cultivar is ‘Pisang Awak’, and it belongs to the tetraploid AABB genome group. Initial identification was performed by assessing disease symptoms including chlorotic streaks on leaves that became brown and black chlorotic streaks later, resembling those of banana streak disease (Lockhart 1986). BSV was verified via molecular and serological tests. Genomic DNA from leaf tissue of three different symptomatic plants and two healthy plants was extracted using a DNeasy Plant Mini Kit (Qiagen, Valencia, CA). Samples were tested for the presence of BSV by two separate PCR amplification methods. One was targeting the aspartic protease (AP) and reverse transcription (RT) regions of ORF3 using primer pair BSV 4673 (5′-GGAATGAAAGAGCAGGCC-3′) and BSV 5317 (5′-AGTCATTGGGTYCAACCTCTGTCCC-3′) with an amplicon size of 644 bp (Manoranjitham et al. 2012). Another PCR analysis was targeting the coat protein (CP) region of ORF3 with primer pair BSV 156 (5′-TTACCTCCAGCACAAAGTCG-3′) and BSV 962 (5′-TTCTCCACAGGCATAACACC-3′) designed in this study with a product size of 806 bp. Both PCR reactions for all six symptomatic samples produced the expected sizes of the fragments for BSV; however, two samples from the healthy plants did not produce any bands. The amplified products were then sequenced and subjected to BLAST analysis for further identification. Sequence analysis revealed that the obtained partial sequence of the AP and RT region (MN567071) shared 100% identity to corresponding sequences from BSV OL virus isolate BSOLV-IN2 (accession no. JQ409540). Furthermore, the obtained CP gene sequence (MN567072) also showed 100% identity with BSV isolate BSOLV-IN2. Samples were also tested for the presence of BSV by real-time PCR with primers BSV 1075 (5′-CACATTGACGGAAAGGACAACG-3′) and BSV 1198 (5′-TGTGAAATACCTCCTCCACTGC-3′) targeting the RNase H gene (Delanoy et al. 2003), and the results confirmed its identity as BSV. In addition to the molecular tests, a DAS-ELISA test was carried out on the remaining symptomatic leaf tissues for further confirmation of BSV according to the manufacturer’s protocol (Nano Diagnostics, Fayetteville, AR). All three samples tested by ELISA were positive for BSV. To the best of our knowledge, this is the first report of BSV infecting Musa spp. in Georgia. This virus could pose an imminent threat to the newly growing banana industry in this area if it spread in banana fields under conditions in Georgia. Our findings will be helpful for banana growers in Georgia by taking appropriate control strategies to combat this viral disease. Further research is needed to elucidate epidemiology, symptomatology, vector transmission, and crop losses due to BSV in Georgia and the United States.