Differential sets are a vital component of race analysis. The aim is to have a set of differential varieties, ideally each with a different single resistance gene, which can distinguish races by their qualitative differences in reactions to different pathogen strains. Numerous different differential sets are in use by rust labs undertaking race analysis on a routine basis.

This current lack of consistency in differential sets between rust labs makes international comparison of results extremely difficult. As a result of the recognition of the emerging threat posed by new races of stem rust like Ug99 and the clear need for global collaboration and consistency, a new international set of differentials has been agreed upon by a panel of global rust experts. Partners in the BGRI are now using the following international core set of differentials to ensure global consistency for race analysis. Optional additions to the international core set can be made by individual labs to cover local needs.

For more information about obtaining seed of the International core diferential set. Please contact:

Dr. K. Nazari, ICARDA, P.O. Box 5466, Aleppo, Syrian Arab Republic. Email: K.Nazari@cgiar.org

Dr. T. Fetch, AAFC, Cereal Research Centre, 195 Dafoe Road, Winnipeg, Canada R3T 2M9. Email: Tom.Fetch@AGR.GC.CA

BGRI International Core Differential Set – Stem Rust (ordered by sets used in North American nomenclature system)

Set	Gene	LIT	Diff line for world distribution, April 2009	Origin/Pedigree	Source
1	Sr5	0	ISr5-Ra CI 14159	Thatcher/Chinese Spring	Jin, USDA
	Sr21	1-	T monococcum/8*LMPG-6 DK13	Einkorn CI 2433	Fetch, AAFC
	Sr9e	1- to 2-	Vernstein PI 442914	Little Club //3* Gabo /2* Charter /3/3* Steinwedel / CI 7778	Jin, USDA
	Sr7b	2	ISr7b-Ra CI 14165	Hope/Chinese Spring	Jin, USDA
2	Sr11	; to 2-	Yalta PI 155433	Kenya C6402/Pusa4//Dundee	Park, Australia
	Sr6	0;	ISr6-Ra CI 14163	Red Egyptian/Chinese Spring	Jin, USDA
	Sr8a	2- to 2	Mentana W1124 PI 221154	Rieti / Wilhelmina // Akagomughi	Park, Australia
	Sr9g	2-	Acme CI 5284	Selection from Kubanka (CI 1516)	Pretorius, SA
3	Sr36	0;	W2691SrTt-1 CI 17385	CI 12632 T. timopheevii	Jin, USDA
	Sr9b	2	Prelude*4/2/Marquis*6/Kenya 117A	Kenya 117A	Fetch, AAFC
	Sr30	1+ to 2	Festiguay W2706 PI 330957	Festival / Uruguay C10837	Park, Australia
	Sr17	;1	Prelude/8*Marquis*2/2/Esp 518/9	Esp 518/9	Fetch, AAFC
4	Sr9a	1- to 2-	ISr9a-Ra CI 14169	Red Egyptian/Chinese Spring	Jin, USDA
	Sr9d	1- to 1	ISr9d-Ra CI 14177	Hope/Chinese Spring	Jin, USDA
	Sr10	;1N to 3C	W2691Sr10 CI 17388	Marquis*4/Egypt NA95/2/2*W2691	Jin, USDA
	SrTmp	2-	CnsSrTmp	Triumph 64 (CI 13679)/Chinese Spring	Jin, USDA
5	Sr24	1- to 2-	LcSr24Ag	Little Club/Agent (CI 13523)	Jin, USDA
	Sr31	1- to 2	Kavkaz/Federation4	Kavkaz	Pretorius, SA
	Sr38	X=	Trident	Spear*4/VPM (PI 519303)	Park, Australia
	SrMcN	2-	McNair 701 (CI 15288)		Jin, USDA

Source: Prof. Z.A. Pretorius, University of the Free State, South Africa