Grapevine viroid 1B, a new member of the apple scar skin viroid group contains the left terminal region of tomato planta macho viroid

GV1 B is one of five viroids that have recently been purified from grapevines. GV1 B has now been sequenced and its 363 nucleotide residues can potentially form the typical rod-like structure of viroids with 67% of nucleotides basepaired. GV1B has highest sequence similarity with grapevine yellow speckle viroid (GYSV; 73%) and has a central sequence which is conserved in GYSV and apple scar skin viroid (ASSV) which have been reported to constitute the ASSV group. Therefore, we have placed GV1 B into the ASSV group. GV1 B contains a direct repeat sequence at the terminal portions of its T1 and T2 regions. GV1 B also contains a sequence of 69 nucleotides in the terminal portion of its Ti region which is almost identical to the corresponding region in tomato planta macho viroid (TPMV). This provides further evidence of the importance of RNA recombination in viroid evolution.