Discovery and molecular mapping of a new gene conferring resistance to stem rust, Sr53, derived from Aegilops geniculata and characterization of spontaneous translocation stocks with reduced alien chromatin

Abstract

This study reports the discovery and molecular mapping of a resistance gene effective against stem rust races RKQQC and TTKSK (Ug99) derived from Aegilops geniculata (2n = 4x = 28, U(g)U(g)M(g)M(g)). Two populations from the crosses TA5599 (T5DL-5M(g)L·5M(g)S)/TA3809 (ph1b mutant in Chinese Spring background) and TA5599/Lakin were developed and used for genetic mapping to identify markers linked to the resistance gene. Further molecular and cytogenetic characterization resulted in the identification of nine spontaneous recombinants with shortened Ae. geniculata segments. Three of the wheat-Ae. geniculata recombinants (U6154-124, U6154-128, and U6200-113) are interstitial translocations (T5DS·5DL-5M(g)L-5DL), with 20-30% proximal segments of 5M(g)L translocated to 5DL; the other six are recombinants (T5DL-5M(g)L·5M(g)S) have shortened segments of 5M(g)L with fraction lengths (FL) of 0.32-0.45 compared with FL 0.55 for the 5M(g)L segment in the original translocation donor, TA5599. Recombinants U6200-64, U6200-117, and U6154-124 carry the stem rust resistance gene Sr53 with the same infection type as TA5599, the resistance gene donor. All recombinants were confirmed to be genetically compensating on the basis of genomic in situ hybridization and molecular marker analysis with chromosome 5D- and 5M(g)-specific SSR/STS-PCR markers. These recombinants between wheat and Ae. geniculata will provide another source for wheat stem rust resistance breeding and for physical mapping of the resistance locus and crossover hot spots between wheat chromosome 5D and chromosome 5M(g)L of Ae. geniculata.

Genetic analysis of rust resistance genes in global wheat cultivars: an overview

“…To date, approximately 58 stem rust resistance (Sr) genes have been identified [88,89] and numerically designated as Sr1 to Sr58 as part of the International Wheat Genetics Symposium Gene Catalog [26,90]. Among these genes, at least 27 genes, including Sr2 (Yr30), Sr13, Sr21, Sr22, Sr24, Sr25, Sr26, Sr27, Sr28, Sr32, Sr33, Sr35, Sr36, Sr37, Sr39, Sr40, Sr42, Sr44, Sr45, Sr46, Sr47, Sr51, Sr52, Sr53, Sr55 (Lr67/Yr46/ Pm46), Sr57 (Lr34/Yr18/Pm38), and Sr58 (Lr46/Yr29/Pm39), are effective or partially effective against the Ug99 race group [91][92][93][94][95][96][97][98][99][100]. Among these 27 genes, Sr2, Sr13, Sr22, Sr25, Sr26, Sr35, Sr39 and Sr40 were reported to be the most effective against Ug99 [87,[101][102][103].…”

“…The Sr40 gene, located on chromosome 2BS, was transferred from Triticum timopheevii ssp. araraticum to hexaploid wheat [34,96,121,122].…”

Genetic and epigenetic alterations induced by different levels of rye genome integration in wheat recipient

“…The introduction of an alien genetic germplasm is a common method for genetic improvement of wheat. Many wild relatives with important agronomic traits, such as rye (Secale cereale L.), Haynaldia villosa, and Elytrigia elongata, are ideal materials for use in wheat genetic breeding (Qi et al, 2007;Gill et al, 2011;Kang et al, 2011;Liu et al, 2011;Jauhar and Peterson, 2013;Zhou et al, 2014). Rye is a valuable source of resistance, stress tolerance, and high yield genes, and it has been extensively used for yield improvement, disease resistance, and environmental adaptation of common wheat (Friebe et al, 1996;Tang et al, 2009;Ren et al, 2011).…”

Genetics and molecular mapping of stem rust resistance in bread wheat line WR95

“…Of these, Sr31 is effective against all Indian stem rust isolates and Sr2 provides moderate level of resistance at adult plant stage while others are ineffective (Mishra et al 2011). Deployment of combinations of resistance genes, including the genes conferring adult plant resistance should improve the durability of resistance in commercial cultivars by reducing the possibility of corresponding simultaneous mutation events in the pathogen (Liu et al 2011).…”