Virus source and maintenance. Bulbs
from diseased calla lily showing yellow
spot and stripe symptoms on leaves were
collected from Ho-Li Township and the
experiment farm of Taiwan Agricultural
Research Institute (TARI). Some calla lily
plants in the fields, planted from imported
bulbs, were about 3 months old and others
were 3- to 5-month-old tissue culture-derived
seedlings. Diseased bulbs were
grown in 18-cm (7-in.) pots under greenhouse
conditions for subsequent studies.
Chenopodium quinoa Willd., inoculated
with the extracts of diseased plants, developed
local lesions 7 days after inoculation.
Single lesions were isolated and re-inoculated
on healthy plants of C. quinoa. This
process was repeated three times. Two
isolates, RC4 (collected from Ho-Li) and
YC5 (from TARI), inducing systemic infection
in calla lily and mustard (Brassica
juncea L.), were established. For subsequent
experiments, cultures of YC5 and RC4 were
propagated routinely in mustard. For longterm
storage, diseased mustard leaves were
stored in 50% (vol/vol) glycerol at –20°C.