Occurrence of the rust resistance gene Lr37 from Aegilops ventricosa in Argentine cultivars of wheat

Abstract

Leaf rust of wheat (Triticum aestivum L.) caused by the fungus Puccinia triticina (formerly P. recondita f. sp. tritici), is one of the most important foliar diseases of this crop. Lr37 rust resistance gene, which confers resistance in wheat against leaf rust, was introgressed into cultivated wheat from Aegilops ventricosa Tausch. Rust races with virulence to Lr37 have been identified in different countries, but it still provides resistance to a wide range of races and is useful in combination with other resistance genes. There are no reports about the presence, frequency and origin of Lr37 in Argentinean wheat cultivars. In this work, we analyzed 88 registered Argentinean wheat cultivars developed by different breeding companies and institutions during the last 15 years by means of a molecular marker which is diagnostic of the 2NS-2AS translocation which carries Lr37. Only 4 cultivars showed the amplification product associated with this chromosome fragment. These four cultivars which carry the translocated 2NS-2AS chromosome were registered by the same breeding company during the last seven years and all of them have European germplasm in their genealogy. To the best of our knowledge this is the first report of the presence of Lr37 in registered South American cultivars.

Identification of leaf rust resistance genes i n selected Argentinean bread wheat cultivars by gene postulation and molecular markers

“…chromosome 2NS translocated to the short arm of bread wheat chromosome 2AS (McIntosh et al 1995). In agreement with Bulos et al (2006), two between 66 tested cultivars showed the 285-bp diagnostic DNA fragment associated to Lr37. 'Baguette 10' and 'Baguette Premium 11' share European germplasm carrying Lr37 in their genealogy (for example VPM1) suggesting a common origin of Lr37.…”

“…More than sixty genes for leaf rust resistance (Lr), most of them major, seedling or race specific genes, have been catalogued to date in wheat (McIntosh et al 2008;Samsampour et al 2010). However, the gene-for-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 (Johnson, 2000;Bulos et al 2006). Replacement of highly variable land races by higher yielding, pure-line varieties in many parts of the world, including the South Cone, has further reduced the wheat gene pool and favored virulence shifts events in pathogen populations.…”

Genetic structure of Argentinean hexaploid wheat germplasm

“…For example, K1 is composed mainly (70.58%) by cultivars from Nidera and Syngenta breeding programs, as 100% of the cultivars tested and released by these companies were grouped only in K1. It is worthy of note that this germplasm (at least early materials released by Nidera (Bulos et al , 2006), has a European origin, mainly from France, and was introduced gradually to Argentina since 1999. The K1 subpopulation also includes old cultivars from the Klein breeding program, like Klein 32 (released in 1932), Klein Atlas (1963) and Klein Centauro (1989) (Figure 3).…”

Molecular Genetic Variation for Stripe Rust Resistance in Spring Wheat

“…They are abundant in eukaryotic genomes and have been commonly used to facilitate identification and incorporation of durable resistance genes of various diseases in wheat (Gupta et al, 1999). Bulos et al (2006) screened 88 Argentinian wheat cultivars with marker Ventriup-LN2 for the presence of Lr37/Yr17/Sr38 gene complex. Wang et al (2009) screened 226 wheat cultivars and advance lines from Hungary and other countries with the STS marker csLV34 and concluded that this marker can reliably be used for marker assisted selection.…”