![Photo: Sugarcane. Link to photo information](https://webarchive.library.unt.edu/eot2008/20090509202114im_/http://www.ars.usda.gov/is/pr/2009/rsd090206.jpg)
A faster method for detecting ratoon stunting
disease-the most important disease affecting sugarcane production worldwide
(pictured here)has been developed by the Agricultural Research Service
(ARS) and cooperators. Photo courtesy of Michael Irey, U.S. Sugar
Corp. |
![For further reading](https://webarchive.library.unt.edu/eot2008/20090509202114im_/http://www.ars.usda.gov/is/graphics/For-further-reading.gif)
|
New Method Speeds the Detection of Ratoon Stunting
Disease
By Stephanie Yao February 6, 2009
A faster method for detecting ratoon stunting disease (RSD)the
most important disease affecting sugarcane production worldwidehas been
developed by the Agricultural Research
Service (ARS) and cooperators.
RSD has been reported in almost every geographic area where sugarcane
is grown. It causes an average 5 percent yield loss, but under drought
conditions, yield reductions can be as high as 50 percent. RSD is hard to
detect because it has no unique external symptoms, so growers have no way of
knowing if their fields have been infected. The bacterium that causes RSD,
Leifsonia xyli subsp. xyli, also called Lxx, is
extremely difficult to isolate and culture, making it hard to diagnose for
further studies.
ARS plant molecular geneticist
Yong-Bao
Pan with the agency's
Sugarcane
Research Laboratory in Houma, La., and cooperators in China have developed
a rapid and more reliable technique for detecting RSD using standard laboratory
equipment.
Popular RSD detection methods require the use of either antibodies,
which may not be available, or bacterial DNA isolation using toxic organic
solvents such as chloroform and beta- mercaptoethanol, a process which can take
up to four hours. Due to the low concentration of the bacterium in the host,
serological methodstests that use antibodies to detect
infectionhave limited use when conducting a large-scale field RSD disease
survey or RSD-resistance screening during breeding selection.
Pans method uses xylem sap to test for RSD. The plants
xylemthe tissue responsible for the transport of water and soluble
mineral nutrients from the roots throughout the plantcontains optimum
concentrations of Lxx, making it an ideal area for collecting DNA. This
safe technique uses two inorganic buffers to isolate Lxxs DNA,
taking less than an hour to complete. The new method also utilizes general
equipment, such as a centrifuge and a polymerase chain reaction (PCR) machine,
which are more commonly found in labs worldwide.
The PCR method is more sensitive than serological methods and
amplifies the DNA sequences of the bacterial genome in areas where it is hard
to find, such as in xylem. It is thus a more practical method for labs
throughout the world, especially those in developing countries, to detect
RSD.
ARS is the principal intramural scientific research agency of the
U.S. Department of Agriculture.