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Identification of QTLs associated with adult plant resistance to stem rust race Ug99 in the 'Avocet' x 'Pavon76' recombinant inbred line population

By: Njau, P.N.
Contributor(s): Keller, B [coaut.] | McIntosh, R | Huerta-Espino, J [coaut.] | Singh, R.P [coaut.] | Bhavani, S [coaut.].
Material type: materialTypeLabelBookAnalytics: Show analyticsPublisher: 2011Description: p. 189.Online resources: Access only for CIMMYT Staff Summary: Stem rust, caused by Puccinia graminis f. sp. Tritici (Pgt), has historically caused severe losses to wheat production worldwide, but was effectively controlled by resistance for almost 30 years. However, stem rust re-emerged in 1998 in eastern Africa in the form of race Ug99. Furthermore, it has u ndergone changes to produce separate variants with added virulence to resistance genes Sr24 and Sr36. The lineage is once again threatening the global wheat crop. The objective of our study was to identify genomic regions contributing to APR to stem rust in ?Pavon 76?. A recombinant inbred line (RIL) population of 298 lines was previously developed at CIMMYT from a cross between ?Avocet S? and ?Pavon 76. The RILs segregated for APR to Ug99 when evaluated in Kenya for three years. Single year and combined year analyses by inclusive composite interval mapping using 450 DArT markers identified six quantitative trait loci (QTLs) contributing to resistance . avon 76? contributed three QTLs, Sr2-linked QSr.cim-3B-1, Lr46/Yr29/Pm39- linked QSr.cim-1B and QSr.cim-3D (possibly an ortholog of Sr2), which explained 32%, 24% and 20% of the phenotypic variance, respectively. The remaining three QTLs, QSr.cim-3B-2, QSr.cim-4B and QSr.cim-5A, were contributed by ?Avocet? and explained 24%, 8% and 6% of the phenotypic variance, respectively. Our results indicate that it is possible to accumulate several minor genes (each with a small-to-intermediate effect) to produce a variety that exhibits negligible disease levels even under high stem rust pressure.
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Conference proceedings CIMMYT Knowledge Center: John Woolston Library

Lic. Jose Juan Caballero Flores

 

CIMMYT Staff Publications Collection CIS-6339 (Browse shelf) Available
Total holds: 0

Abstract only

Stem rust, caused by Puccinia graminis f. sp. Tritici (Pgt), has historically caused severe losses to wheat production worldwide, but was effectively controlled by resistance for almost 30 years. However, stem rust re-emerged in 1998 in eastern Africa in the form of race Ug99. Furthermore, it has u ndergone changes to produce separate variants with added virulence to resistance genes Sr24 and Sr36. The lineage is once again threatening the global wheat crop. The objective of our study was to identify genomic regions contributing to APR to stem rust in ?Pavon 76?. A recombinant inbred line (RIL) population of 298 lines was previously developed at CIMMYT from a cross between ?Avocet S? and ?Pavon 76. The RILs segregated for APR to Ug99 when evaluated in Kenya for three years. Single year and combined year analyses by inclusive composite interval mapping using 450 DArT markers identified six quantitative trait loci (QTLs) contributing to resistance . avon 76? contributed three QTLs, Sr2-linked QSr.cim-3B-1, Lr46/Yr29/Pm39- linked QSr.cim-1B and QSr.cim-3D (possibly an ortholog of Sr2), which explained 32%, 24% and 20% of the phenotypic variance, respectively. The remaining three QTLs, QSr.cim-3B-2, QSr.cim-4B and QSr.cim-5A, were contributed by ?Avocet? and explained 24%, 8% and 6% of the phenotypic variance, respectively. Our results indicate that it is possible to accumulate several minor genes (each with a small-to-intermediate effect) to produce a variety that exhibits negligible disease levels even under high stem rust pressure.

Global Wheat Program

English

Lucia Segura

INT2843|INT0610

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