Jp. Chen et al., DETECTION AND SEQUENCE-ANALYSIS OF A SPONTANEOUS DELETION MUTANT OF SOIL-BORNE WHEAT MOSAIC-VIRUS RNA2 ASSOCIATED WITH INCREASED SYMPTOM SEVERITY, Virology, 202(2), 1994, pp. 921-929
Repeated passage of soil-borne wheat mosaic virus (SBWMV; wild-type Ok
lahoma field isolate; designated Okl-0) by manual inoculation resulted
in deletion of part of SBWMV RNA2. Deletion was apparent in the popul
ation of RNA2 molecules after only 11 weeks in primary inoculated whea
t plants (called Okl-1) and after 5 passages (Okl-5; 20 weeks) no full
-length RNA2 remained. The extent of deletion in the Oklahoma isolate
was compared with that in the previously studied Lab 1 (Nebraska) isol
ate. RNA2 from Okl-1, Okl-7, and Lab 1 were analyzed by RT-PCR amplifi
cation using sets of primer pairs which spanned all portions of the in
tact molecule. Lab 1 and the new stable isolate, Okl-7, were found to
be deleted for 1058 and 759 nt, respectively, within the region encodi
ng the coat protein-readthrough domain. However, the Okl-7 deletion wa
s in a different position from the Lab 1 deletion. This suggests that
deletions of SBWMV RNA2 which occur during serial manual inoculation a
re not directed toward production of a conserved, truncated form of th
e 84-kDa extended coat protein, but might reflect an RNA sequence-depe
ndent event. (C) 1994 Academic Press, Inc.