Analysis of the intergenic region of tomato spotted wilt Tospovirus mediumRNA segment

The intergenic region (IGR) of the medium (M) RNA of tomato spotted wilt To spovirus (TSWV) isolates naturally infecting peanut (groundnut), pepper, po tato, stokesia, tobacco and watermelon in Georgia (GA) and a peanut isolate from Florida (FL) was cloned and sequenced. The IGR sequences were compare d with one another and with respective M RNA IGRs of TSWV isolates from Bra zil and Japan and other tospoviruses. The length of M IGR of GA and FL isol ates varied from 271 to 277 nucleotides. The M IGRs of TSWV from potato and stokesia, and tobacco and watermelon were identical with each other in the ir length and sequence. IGR sequences were more conserved (95-100%) among t he populations of TSWV from GA and FL, than when compared with those of TSW V isolates from other countries (83-94%). The conserved motif (CAAACTTTGG) present in the IGRs of both M and small (S) RNAs of a Brazilian isolate of TSWV was also conserved in the isolates studied. Cluster analysis of the IG R sequences showed that all GA and FL isolates are closely clustered and ar e distinct from the TSWV isolates from other countries as well as from othe r tospoviruses. (C) 1999 Elsevier Science B.V. All rights reserved.