First Report of Canna yellow mottle virus in Kenya

Kenya is an important exporter of cut flowers for the European markets. During surveys conducted in April 2014, canna plants (Canna indica) were observed with distinctly different virus-like symptoms in two regions of Kenya. Leaves collected in Nairobi had yellow/green chlorotic mottle, necrotic mottle, and veinal streaking symptoms (Fig. 1). This sample was designated K1. Leaves collected in Kericho had green mosaic symptoms (Fig. 1), and this sample was designated K2. Both samples were examined by transmission electron microscopy (TEM) and immunosorbent electron microscopy (ISEM) for the presence of the viruses known to occur in cannas. These are: Canna yellow mottle virus (CaYMV), Canna yellow streak virus (CaYSV), Bean yellow mosaic virus (BYMV), a potyvirus resembling CaYSV (B. Lockhart, personal communication), Cucumber mosaic virus (CMV), and Tomato aspermy virus (TAV). TEM observations of negatively stained, partially purified leaf tissue extracts (Ahlawat, Pant, et al. 1998) from K1 and K2 detected only bacilliform particles, with an approximate diameter of 30 nm and length of 120 nm, typical of CaYMV. No particles were observed in samples from non-symptomatic plants. Trapping and decoration of particles by ISEM (Ahlawat et al. 1998) using a polyvalent antiserum raised against a mixture of isolates of Sugarcane bacilliform virus and Banana streak virus showed typical badnavirus-like particles from both K1 and K2 (Fig. 2). No surveys were completed to determine the percent incidence of CaYMV in Kenya. The presence of CaYMV in the leaves of the two Kenyan isolates was confirmed by PCR using CaYMV-specific primers (Momol et al. 2004). These CaYMV-specific primers generated the expected 565-bp product, corresponding to the virus polyprotein, from total DNA extracted from symptomatic leaves using a Plant DNeasy Mini Kit (Qiagen, MD, USA). No products were amplified from non-symptomatic plants. PCR amplified products were purified using a Pure link Quick PCR purification kit (Invitrogen by Life Technologies). PCR products were ligated, cloned (pGEM-T Easy Vector System; Promega, Fitchburg, WI USA) and sequenced (UMN-BMGC, St. Paul, MN USA) to confirm their identity. Raw sequences were edited (Sequencher, Gene Codes Corporation, Ann Arbor, MI USA) and deposited in GenBank under accession number KJ890481 (K1) and KJ890482 (K2). Isolate K1 and K2 share 98.6% nucleotide sequence identity and 99.5% amino acid sequence identity (Pearson et al. 1997). K1 has 99% nucleotide sequence identity to reported CaYMV polyprotein gene sequences (HE774734.1, KJ890482.1, HE774733.1, EF189148.1, and EF189147.1). K2 has 99% nucleotide sequence identity to published CaYMV polyprotein gene sequences (HE774734.1, KJ890481.1, HE774733.1, and EF189148.1).