“…1a, is one of the most thoroughly studied of all viruses (Markham and Smith, 1949;Matthews, 1991;Rubio-Huertos et al, 1967;Finch and Klug, 1966;Hirth and Givord, 1988;Mellema and Amos, 1972). The TYMV genome is made up of an M r ϭ 1.9 ϫ 10 6 , single-stranded RNA of 6218 bases (Hirth and Givord, 1988) and a 694-nucleotide subgenomic RNA that is included in most virions.…”