Title: Tapping into sorghum's weed-fighting capabilities to give growers more options
[EurekAlert 15 June 2010] -- By unlocking the genetic secrets of sorghum,
Agricultural Research Service (ARS) scientists have found a way to make one of
the world's most important cereal crops a better option for growers. Researchers
at the ARS Natural Products Utilization Unit in Oxford, Miss. also may have
opened a door to reducing pesticide use in the production of other crops.
Sorghum secretes a compound known as sorgoleone that is instrumental in
helping the plant combat weeds. But in a way it does its job too well. Certain
crops don't grow well in fields where sorghum has been raised, causing problems
for growers who want to plant different crops on those fields.
The research team at Oxford included molecular biologist Scott Baerson,
chemist Agnes Rimando, research leader Stephen O. Duke, plant physiologist
Franck E. Dayan, molecular biologist Zhiqiang Pan, and plant physiologist Daniel
Cook, who now works at the ARS Poisonous Plant Research Laboratory in Logan,
Utah.
The team started with two pieces of evidence that helped them address the
problem. Previous studies showed that sorgoleone is produced in the plant root
hairs, and that a special type of enzyme within the plant plays a major role in
sorgoleone production.
Using a strategy called sequence tagging, the scientists searched an
established sorghum genome database for gene sequences associated with that
class of enzymes. They found two gene sequences expressed in the plant root hair
cells that produced the enzymes. When they silenced the two gene sequences, it
dramatically reduced sorgoleone levels in the sorghum plants produced.
The results, published in The Plant Cell, could lead to sorghum lines
without the soil toxicity problem, as well as lines with higher levels of
sorgoleone that offer superior weed-fighting capabilities without posing
environmental hazards.
This discovery will enable researchers to look for similar gene sequences in
other crops to increase their natural pest-fighting capabilities and reduce the
need for pesticides. Baerson and his colleagues have already identified similar
sequences in rice that are involved in production of defense-related
enzymes.