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3PM Report: Barberry Identity Verification and Black Stem Rust Survey

A new highly virulent race of Puccinia graminis, Ug99, which was discovered in East Africa in 1999, has spread to other parts of Africa and to wheat growing regions in the Middle East and Central Asia.  According to the Food and Agriculture Organization (FAO), the unique thing about Ug99 is the broad spectrum of virulence it exhibits as not only has it defeated the Sr31 resistance gene, a widely used gene that has been effective in wheat for over 30 years, but also most of the resistance genes of wheat origin and other key genes like Sr38 from related species.  Since its discovery more than a decade ago, Ug99 has held the agricultural world in suspense as governments and scientists rush to protect wheat crops.

To protect Michigan’s wheat industry from the threat posed by Ug99 and new strains of other rust fungi, Michigan Department of Agriculture and Rural Development (MDARD) in collaboration with the U.S. Department of Agriculture, conducted a barberry and black stem rust survey in the state in 2010-2011.  The objectives of the survey were: 1) to verify that all barberry cultivars offered for sale in the state were those of Japanese barberry (Berberis thunbergii), a species known to be immune to black stem rust;  2) that Common barberry had not reestablished in the state; and 3) to determine the status of black stem rust in Michigan wheat fields.

Methods and Procedures
In 2010, a total of 150 barberry plants representing 17 cultivars from propagating nurseries were collected by MDARD and shipped to Dr. Mark Brand’s laboratory at the University of Connecticut for DNA analysis using seven Amplified Fragment Length Polymorphism (AFLP) markers.  An additional 161 plant samples were collected from retail outlets and maintained in a hoop house for DNA extraction at MDARD’s Plant Pathology Laboratory in East Lansing.  Polymerase Chain Reaction (PCR) quality DNA was extracted from the plant samples and sent to Dr. Brand’s laboratory for analysis and cultivar determination.  

In February 2011, field surveys for Common barberry and black stem rust were conducted in accordance with standard wheat scouting and inspection procedures.  

Findings
The seven-marker AFLP procedure used at Dr. Brand’s laboratory successfully confirmed all 150 barberry plant samples from the propagating nurseries as true-to-name for their respective cultivars of B. thunbergii.  AFLP analysis of the 161 retail outlet samples confirmed 151 of the samples as true-to-name and 10 as mixtures of B. thunbergii cultivars.  
Black stem rust of wheat was not detected in surveyed fields; however, wheat leaf rust and stripe rust, common pests found in all wheat growing regions of the world, were detected on samples from two fields.  Field surveys did not detect wild populations of Common barberry.  The survey results indicate that Common barberry has not reestablished in the surveyed wheat production areas of the state.

Citations:
Stem Rust Ug99 – an Agricultural Bully. Scientific American: June 20, 2011.

The Emergence of Ug99 Races, a threat to World Wheat Production. Annual Review of Phytopathology: Sept. 2011- Vol. 49, pp. 465-481.

Molecular Identification of Japanese Barberry (Berberis thunbergii) Cultivars Using Amplified Fragment Length Polymorphism. HortScience: June 2007, vol. 42, no. 3, pp. 478-482.