First report of cacao mild mosaic virus associated with symptomatic commercial cacao (Theobroma cacao) trees in Puerto Rico.
In September 2019, leaf chlorosis and purple mottling on unripe pods were observed on cacao trees (Theobroma cacao) genotype RIM-52 on a commercial farm in Puerto Rico (PR). In December 2019, ripe pods with red spots were found on an additional RIM-52 tree on the same farm. Tissue sampled in September (one symptomatic leaf and one symptomatic pod from tree 1) and December (two symptomatic pods and two asymptomatic leaves from tree 2) was tested using recently developed molecular diagnostics for Cacao mild mosaic virus (CaMMV) and Cacao yellow vein banding virus (CYVBV). Total DNA was isolated and used as template for polymerase chain reaction amplification of the movement protein and coat protein (MP-CP) domain of CaMMV and CYVBV. The MP-CP sequences (GenBank numbers MT253655 to MT253658 and MT262888 to MT262891) shared 95.2 to 96.0% nucleotide identity with CaMMV (accession KX276640). Based on Badnavirus species demarcation criterion, of ≥80% nucleotide identity for the RT-RNase H domain, the PR (accessions MT253659 to MT253662) and Trinidad (accession KX276640) isolates are the same species, CaMMV, with 95.9 to 96.3% nucleotide identity. This is thought to be the first report of CaMMV in PR and believed to be the first report outside of Trinidad.