2 SEPARATE REGIONS IN THE GENOME OF THE TOBACCO ETCH VIRUS CONTAIN DETERMINANTS OF THE WILTING RESPONSE OF TABASCO PEPPER

Infection of Tabasco pepper by the tobacco etch virus (TEV) typically causes wilting associated with root necrosis, However, a strain of TEV , designated TEV nonwilting (TEV NW), is able to infect Tabasco pepper plants but does not cause wilting, In order to locate the genetic det erminants responsible for the wilting response, a full-length cDNA clo ne of TEV NW from which infectious transcripts can be derived was made , A number of chimeric constructs were prepared by substituting cDNA f ragments between TEV HAT (which causes wilting) and TEV NW clones, Thi s approach was used to identify two wilting determinants in TEV HAT: o ne encompasses the 3' one-third of the P3 coding region; the other spa ns the 3' end of the CI, the 6-kDa protein, and the 5' end of the VPg- NIa coding regions, Substitution of both these TEV NN fragments into T EV HAT resulted in infection but not wilting of Tabasco pepper, while the replacement of either of the fragments alone did not alter the wil ting response, This indicates that both TEV NW regions contain determi nants necessary but not sufficient to alter the wilting response and t hat both must be present in order to avoid the wilting response, There was no difference between the in vitro transcription-translation prod ucts derived from constructs containing these regions from TEV HAT and TEV NW.