Wheat is infected by leaf rust disease (Puccinia triticina Eriks.) almost everywhere it is cultivated. The dynamic nature of P. triticina populations affects the effective life span of genes conferring leaf rust resistance (Lr genes). Genetic diversity and combinations of Lr genes should be used to achieve durable resistance. Toropi, a Brazilian wheat cultivar, has maintained leaf rust resistance since its release in 1965, suggesting that it is a good candidate for durable resistance. Two recessive complementary adult plant genes were previously described in Toropi. The objective of this study was to characterize and map the sources of resistance present in Toropi. Double haploid (DH) populations developed by crossing the susceptible leaf rust cultivar Thatcher with Toropi were analysed in Canada (Glenlea – 2010 and Portage La Prairie – 2011), New Zealand (Lincoln – 2010 and 2011) and in Brazil (Parana – 2011), and in greenhouse. The leaf rust reactions indicated the presence of at least four leaf rust resistance genes in Toropi: one seedling gene and three adult plant genes. The seedling resistance gene Trp-Se, responsible for immune response in New Zealand, was mapped on chromosome 3D. QTL analyses identified a QTL associated with leaf rust resistance (QLr.crc-5AL.1) on chromosome 5AL, which overlapped with a QTL for stripe rust (QStr.crc-5AL.1) in the same population. This gene, designated Trp1, is believed to be one of the two adult plant complementary partial resistance genes. The position of the Trp-2 is not confirmed yet. One minor race specific adult plant gene, temporarily designated Trp-3, was mapped on 4BL chromosome. The Lr genes in Toropi confer minor effects against leaf rust, except for Trp-Se, which conditioned immunity in New Zealand. However, when the Toropi Lr genes were combined an almost immune response resulted. Toropi had a very good leaf rust resistance in South and North America, and in New Zealand. The molecular markers identified during this project could facilitate the incorporation of the Toropi genes in new cultivars, helping to achieve more diverse and durable wheat.
| Identifer | oai:union.ndltd.org:MANITOBA/oai:mspace.lib.umanitoba.ca:1993/14404 |
| Date | 04 January 2013 |
| Creators | Barcellos Rosa, Silvia |
| Contributors | Brule-Babel, Anita (Plant Science) McCallum, Brent (Plant Science), Cloutier, Sylvie (Plant Science) Hausner, Georg (Microbiology) Spaner, Dean (University of Alberta) |
| Source Sets | University of Manitoba Canada |
| Detected Language | English |
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