TYPES OF VARIATION IN DNA-A AMONG ISOLATES OF EAST-AFRICAN CASSAVA MOSAIC-VIRUS FROM KENYA, MALAWI AND TANZANIA

Complete nucleotide sequences of the DNA-A-like molecules of three Eas t African cassava mosaic virus (EACMV) isolates from Kenya (-K, 2801 n t) and Malawi (-MH and -MK, both 2804 nt) were determined. These seque nces were compared with that published for a Tanzanian isolate (-T, 28 01 nt) and the partial sequence of a third Malawian isolate. Intergeni c region sequences of all isolates, and deduced amino acid sequences o f their AC1 (Rep) proteins, each formed a tightly related cluster that was distinct from the comparable components of other begomoviruses. O ther complementary-sense genes (AC2, AC3, AC4) differed between EACMV isolates in a way consistent with the accumulation of point mutations. In contrast, virus-sense genes (CP, AV2) of isolates -MH and -MK diff ered (substantially for AV2) from those of other EACMV isolates but so mewhat resembled those of tomato yellow leaf curl virus - Israel, sugg esting they had been acquired by recombination with an unidentified be gomovirus.