Banana bract mosaic virus
Banana bract mosaic virus (BBrMV) causes significant yield losses in banana and abacá in the Philippines, India and Sri Lanka. BBrMV could potentially be confused with Sugarcane mosaic virus (syn. Abaca mosaic virus), another potyvirus infecting both banana and abacá in the Philippines and inciting similar foliar symptoms.
A full description of the symptoms caused by BBrMV is provided by Thomas et al. (1999), from which the following summary is derived. Mosaic symptoms on the male flower bracts are diagnostic and distinct from those caused by all other known viruses of banana. Mosaic patterns, stripes and spindle-shaped streaks may also be visible on the base of the pseudostem when the leaf sheaths are removed.
Infection is often associated with an increase in pigmentation on the pseudostem, and sometimes symptoms are chlorotic on a red background and sometimes reddish, yellow or chlorotic on a green background. Leaf symptoms, consisting of spindle-shaped lesions and streaks running parallel to the veins, are not always evident but can occur on recently infected young plants.
BBrMV has flexuous virus particles, each 750 nm × 11 nm and containing a single coat protein (CP) of 39 kDa. Several partial genomic sequences are available on GenBank, covering the CP and the C-terminus of the nuclear inclusion body (NIb) protein. BBrMV is transmitted by at least three species of aphids (Aphis gossypii, Rhopaloshiphum maidis and Pentalonia nigronervosa) in the non-persistent manner. Infections are also perpetuated by vegetative propagation of plants.