Identification of molecular markers linked to adult plant leaf rust resistance gene Lr48 in wheat and detection of Lr48 in the Thatcher near-isogenic line with gene Lr25

Abstract

The recessive adult plant resistance (APR) gene Lr48 in wheat was tagged with flanking random amplified polymorphic DNA (RAPD) markers. Markers S336 775 in coupling and S3 450 in repulsion with Lr48 were identified in wheat line CSP44. Tests of these markers on available Thatcher near-isogenic lines (NILs) detected the likely presence of Lr48 in TcLr25. A test of allelism of APR involving the cross TcLr25 9 CSP44 indicated that Lr48 was present in both lines. A separate experiment on inheritance of resistance in an F 2 population of TcLr25 9 Agra Local confirmed the presence of a dominant seedling resistance gene (Lr25) and a recessive APR gene (Lr48) in TcLr25. This study demonstrated the value of molecular markers in identifying the presence of masked genes in genetic stocks where direct phenotyping failed to detect their presence.

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

“…Conversely, adult plant resistance (APR) is polygenic, race-nonspecific, horizontally controlled by minor genes and non-hypersensitive, slow rusting or partial and durable in nature. However, most Lr genes confer major, seedling or race-specific resistance and follow the gene-for-gene concept, leading to a hypersensitive response (HR) or programmed cell death [29][30][31]. A small number of APR genes, such as Lr34 and Lr46, are very important for breeding because they have been shown to confer durable, long-term resistance in different environments and against diverse fungus pathotypes [32].…”

Identification of microsatellite markers linked to leaf rust resistance gene Lr25 in wheat

“…While no virulent pathotypes to Lr25 resistance have been reported from India in the past, the gene is yet to be utilised in wheat breeding due to the poor agronomic backgrounds of its carrier lines (McIntosh et al 1995;Samsampour et al 2010). Several other effective genes, such as Lr9, Lr19, Lr24 and Lr28, have been introgressed into breeding materials, although all except Lr24 and Lr25 have matching virulence in P. triticina populations in specific regions in the Asian sub-continent (Bhardwaj et al 2010).…”

“…The utility of coupling and repulsion phase-linked markers has been established by Samsampour et al (2009Samsampour et al ( , 2010 when pyramiding dominant genes Lr24 and Lr28, along with a recessive adult plant resistance gene Lr48. The markers Xgwm538 and Xgwm6 functioned as dominant null allele markers, presumably due to the lack of primerbinding sites in the resistant parent TcLr25.…”

Recent Advances on Integrated Foliar Disease Management with Special Emphasis in Argentina Wheat Production

“…Considering leaf rust, more than sixty genes for leaf rust resistance (Lr), most of them major or race specific genes, have been catalogued to date in wheat [45,46]. However, the genefor-gene interaction between host resistance genes and pathogen virulence genes combined by virulence shifts in pathogen populations have reduced the effectiveness of a significant number of major leaf rust resistance genes [47,48].…”