Pm. Schenk et al., MOVEMENT OF BARLEY MILD MOSAIC AND BARLEY YELLOW MOSAIC-VIRUSES IN LEAVES AND ROOTS OF BARLEY, Annals of Applied Biology, 126(2), 1995, pp. 291-305
Leaves of barley plants were mechanically inoculated with barley mild
mosaic virus (BaMMV) and roots were inoculated using viruliferous zoos
pores of the fungus vector Polymyxa graminis. At intervals after inocu
lation, leaves and roots were tested by different methods to detect vi
rus coat protein (ELISA or Western blot) or nucleic acid (slot-blot or
reverse transcriptase-PCR). Following inoculation with zoospores, vir
us could be detected in roots after 1 wk (Western blot or PCR) but not
until 3-4 wk by ELISA. Virus moved to leaves in 5-6 wk but, except at
temperatures of about 20 degrees C, plants had to be cut back close t
o soil level to stimulate virus movement. Following mechanical inocula
tion, virus could be detected in leaves of a susceptible cultivar with
in 5 days by ELISA and 3 days by the other methods. Western blots and
PCR showed that virus was present in the roots by 5 days. BaMMV was no
t detected by any method in leaves or roots of a resistant cultivar, i
ndicating that the virus did not multiply in it. When leaves were mech
anically inoculated on a small area only, BaMMV capsid protein was det
ected below the inoculated site at 4 days and in young growing leaves
and roots at 13 days after inoculation but never above the inoculation
site or in older leaves. After stem extension began, new leaves of in
fected plants were free of symptoms. The results are compared to obser
vations of plants infected with barley yellow mosaic virus (BaYMV). It
is proposed that movement of BaMMV and BaYMV is strongly related to t
he phloem transport and to the source-sink pattern of winter barley pl
ants.