IDENTIFICATION OF PIPER YELLOW MOTTLE VIRUS, A MEALYBUG-TRANSMITTED BADNAVIRUS INFECTING PIPER SPP IN SOUTHEAST-ASIA

A previously undescribed badnavirus was found to be a causal agent of a disease of black pepper (Piper nigrum) in Malaysia, the Philippines, Sri Lanka and Thailand, and was also associated with a disease of bet elvine (P. betle) in Thailand. Disease symptoms included chlorotic mot tling, chlorosis, vein-clearing, leaf distortion, reduced plant vigor and poor fruit set. The virus, named Piper yellow mottle virus (PYMV), had non-enveloped bacilliform virions averaging 30 x 125 nm in size a nd containing a double-stranded DNA genome. An isolate of PYMV from Th ailand was transmitted by mechanical inoculation and by the citrus mea lybug, Planococcus citri, from infected P. nigrum and P. betle to heal thy P nigrum seedlings, which developed symptoms similar to those obse rved in naturally-infected plants. A serological relationship between PYMV and isolates of banana streak (BSV) and sugarcane bacilliform (Sc BV) viruses, but not six other badnaviruses, was detected by immunosor bent electron microscopy (ISEM). Genomic PYMV sequences were amplified by polymerase chain reaction (PCR) using badnavirus-specific oligonuc leotide primers, and sequence analysis comparisons of the putative rev erse transcriptase (RT) domain showed PYMV to be closely related to ot her mealybug-transmitted badnaviruses. Black pepper infected with PYMV sometimes contained one or more isometric virus-like particles, and P YMV may therefore be only one component of a virus complex infecting b lack pepper in Southeast Asia.