Scientist Sleuths Finger "Crazy Root"
Accomplice By Jan
Suszkiw March 9, 2007
The beet necrotic yellow vein virus (BNYVV) has long been thought to
act alone in inflicting rhizomania, one of the costliest diseases of
sugarbeets. But it may actually have a partner in crime, Agricultural Research
Service (ARS) scientists now suspect.
Rhizomania, also known as "crazy root," causes a thick "beard" of
feathery hairs to sprout from the taproot of infected sugarbeets. Severe
outbreaks can diminish sucrose yields by as much as 40 percent.
In October 2005, ARS plant pathologist
Weiland noticed something odd while examining diseased specimens that
colleague and ARS scientist
Larson had collected from a commercial beet field near Greeley, Colo.
Although most of the plants sported the telltale beard, the BNYVV was nowhere
to be foundat least, not according to the antibody-based tests Weiland
In follow-up studies at the ARS
River Valley Agricultural Research Center in Fargo, N.D., Weiland
inoculated a common weed and a sugarbeet hybrid with extracts from the infected
root specimens. Yellow lesions appeared on the leaves in five dayssooner
than would have occurred if rhizomania were the culprit. Hexagonal particles
within the cytoplasm of the plant cells revealed a mystery virus. By teasing
out the virus' genome and sequencing it, Weiland and colleagues were able to
conduct a search of published viral genomesand their identifying coat
proteinsfor a match.
Surprisingly, their match was the beet black scorch virus (BBSV),
known previously to occur only in China, according to Weiland. In northern
China, BBSV reportedly inflicts black, scorch-like marks on sugarbeet leaves.
However, the rhizomania-like symptoms that Weiland's group observed in U.S.
beet specimens may reflect genomic changes in the U.S. isolates of BBSV.
Besides determining where, when and how the virus entered the United
States, the team is trying to figure out whether BBSV is, by itself, a danger
to American beets or only in the presence of other diseases such as rhizomania.
about the research in the March 2007 issue of Agricultural Research
ARS is the U.S. Department of
Agriculture's chief scientific research agency.