[Show abstract][Hide abstract] ABSTRACT: Oat (Avena sativa L.) productivity is affected by crown rust (Puccinia
coronata f. sp. avenae) and stem rust (Puccinia graminis f. sp. avenae) worldwide.
Control of these diseases has been through the use of host resistance genes, but
frequent changes in pathogen virulence provide a continuing threat to oat production.
Wild oat species have been a major source of diversity for the improvement of
cultivated oat. Many rust resistance genes, as well as genes providing resistance to
other major oat diseases, have been found in wild oat species as well as in landraces
and cultivated species and have been utilised in plant breeding. However, the transfer
of resistance from wild diploid and tetraploid species to cultivated hexaploid oat
is difficult because their chromosomes do not pair readily. Nevertheless, many
improved oat cultivars possess alien-derived rust resistance genes and occupy considerable
acreage in the major oat-producing regions of the world. This chapter
reviews the major developments and their impacts on oat breeding, specifically
through alien gene transfer from wild and related species
Alien Gene Transfer in Crop Plants, Volume 2: Achievements and Impacts, Edited by A. Pratap and J. Kumar, 01/2014: chapter Oat; Springer Science+Business Media.
[Show abstract][Hide abstract] ABSTRACT: Ghazvini, H., Hiebert, C. W., Zegeye, T. and Fetch, T. 2012. Inheritance of stem rust resistance derived from Aegilops triuncialis in wheat line Tr129. Can. J. Plant Sci. 92: 1037-1041. Stem rust, caused by Puccinia graminis f. sp. tritici (Pgt), is a devastating disease of wheat that can cause serious grain yield reduction. The emergence of Pgt race TTKSK (Ug99) and new variants in Africa is considered a threat to wheat production worldwide. Among the primary gene pool of wheat, only a few stem rust resistance (Sr) genes confer resistance to TTKSK. Wild relatives of common wheat are an important source of disease resistance. A preliminary study indicated that the common wheat line Tr129, which contains one or more Aegilops triuncialis translocations, is resistant to race TTKSK. The goal of this study was to elucidate the inheritance of resistance to Pgt in line Tr129 and investigate the novelty of the gene(s) conferring resistance. A population was generated by crossing RL6071 with Tr129 and F-2 and F-3 progeny were inoculated with Pgt race MCCF at the first leaf stage. Segregation of F-2 plants fit a 15:1 ratio (chi(2)(15:1) = 1.48, P = 0.22) indicating two dominant genes in Tr129 conditioned stem rust resistance to race MCCF. Segregation of F-3 families also fit a 7:8:1 ratio (chi(2)(7:8:1) = 3.28, P = 0.19) confirming the presence of two dominant genes. This is first report of stem rust resistance transferred to wheat from Ae. triuncialis.
Canadian Journal of Plant Science 11/2012; 92(6):1037-1041. DOI:10.4141/CJPS2011-248 · 0.92 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Stem rust, caused by Puccinia graminis f. sp. tritici, is a devastating disease of wheat. The emergence of race TTKSK (Ug99) and new variants in Africa threatens wheat production worldwide. The best method of controlling stem rust is to deploy effective resistance genes in wheat cultivars. Few stem rust resistance (Sr) genes derived from the primary gene pool of wheat confer resistance to TTKSK. Norin 40, which carries Sr42, is resistant to TTKSK and variants TTKST and TTTSK. The goal of this study was to elucidate the inheritance of resistance to Ug99 in Norin 40 and map the Sr gene(s). A doubled haploid (DH) population of LMPG-6/Norin 40 was evaluated for resistance to the race TTKST. Segregation of 248 DH lines fitted a 1:1 ratio (χ (2) 1:1= 0.58, p = 0.45), indicating a single gene in Norin 40 conditioned resistance to Ug99. This was confirmed by an independent F(2:3) population also derived from the cross LMPG-6/Norin 40 where a 1:2:1 ratio (χ (2)1:2:1 = 0.69, p = 0.71) was observed following the inoculation with race TTKSK. Mapping with DNA markers located this gene to chromosome 6DS, the known location of Sr42. PCR marker FSD_RSA co-segregated with Sr42, and simple sequence repeat (SSR) marker BARC183 was closely linked (0.5 cM) to Sr42. A previous study found close linkage between FSD_RSA and SrCad, a temporarily designated gene that also confers resistance to Ug99, thus Sr42 may be the same gene or allelic. Marker FSD_RSA is suitable for marker-assisted selection (MAS) in wheat breeding programs to improve stem rust resistance, including Ug99.
[Show abstract][Hide abstract] ABSTRACT: Stem rust (caused by Puccinia graminis Pers.:Pers. f. sp. tritici Eriks. & E. Henn.) has re-emerged as a threat to wheat production with the evolution of new pathogen races, namely TTKSK (Ug99) and its variants, in Africa. Deployment of resistant wheat cultivars has provided long-term control of stem rust. Identification of new resistance genes will contribute to future cultivars with broad resistance to stem rust. The related Canadian cultivars Peace and AC Cadillac show resistance to Ug99 at the seedling stage and in the field. The purpose of this study was to elucidate the inheritance and genetically map resistance to Ug99 in these two cultivars. Two populations were produced, an F(2:3) population from LMPG/AC Cadillac and a doubled haploid (DH) population from RL6071/Peace. Both populations showed segregation at the seedling stage for a single stem rust resistance (Sr) gene, temporarily named SrCad. SrCad was mapped to chromosome 6DS in both populations with microsatellite markers and a marker (FSD_RSA) that is tightly linked to the common bunt resistance gene Bt10. FSD_RSA was the closest marker to SrCad (≈ 1.6 cM). Evaluation of the RL6071/Peace DH population and a second DH population, AC Karma/87E03-S2B1, in Kenya showed that the combination of SrCad and leaf rust resistance gene Lr34 provided a high level of resistance to Ug99-type races in the field, whereas in the absence of Lr34 SrCad conferred moderate resistance. A survey confirmed that SrCad is the basis for all of the seedling resistance to Ug99 in Canadian wheat cultivars. While further study is needed to determine the relationship between SrCad and other Sr genes on chromosome 6DS, SrCad represents a valuable genetic resource for producing stem rust resistant wheat cultivars.
[Show abstract][Hide abstract] ABSTRACT: Crown rust [Puccinia coronata f. sp. avenae] of oat (Avena sativa) was light in southern Manitoba in July in all 3 years during 1999–2001, but by mid-August in 1999 and 2001, heavy crown-rust infections (up to 90% severity) were found in late-planted fields of susceptible oat cultivars and in wild oat (Avena fatua) in Manitoba and eastern Saskatchewan. An important change in 2001 from previous years was the large increase in crown-rust severity (up to 90%) in late-planted fields of 'Triple Crown'. Crown-rust severity remained low on 'AC Assiniboia' during 1999–2001. Using 18 differential oat lines, the number of virulence phenotypes identified in the eastern prairies was 113 from 316 isolates in 1999, 111 from 260 isolates in 2000, and 112 from 217 isolates in 2001. From Ontario, 11 virulence phenotypes were identified from 25 isolates in 1999, 26 from 60 isolates in 2000, and 17 from 26 isolates in 2001. The Ontario and prairie rust populations were dominated by isolates having virulence to Pc38 and Pc39 combined. Virulence frequency to genes Pc68 and Pc96 ranged between 0.9% and 2.8% in the eastern prairies. Virulence to Pc48 increased from 3.8% in 1999 to 22.6% in 2001 in the eastern prairies and decreased from 28.0% in 1999 to 7.7% in 2001 in Ontario. No virulence was detected to Pc94 in Ontario or in the eastern prairies and to Pc58 in Ontario in all 3 years. Isolates with virulence to gene combinations Pc68, Pc96 and Pc48, Pc68 were identified for the first time in the eastern prairie region in 1999 and 2000, respectively.
Canadian Journal of Plant Pathology 03/2010; March 2004(Vol. 26):97-108. DOI:10.1080/07060660409507119 · 1.12 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: New races of wheat stem rust, namely TTKSK (Ug99) and its variants, pose a threat to wheat production in the regions where they are found. The accession of the wheat cultivar Webster (RL6201) maintained at the Cereal Research Centre in Winnipeg, Canada, shows resistance to TTKSK and other races of stem rust. The purpose of this study was to study the inheritance of seedling resistance to stem rust in RL6201 and genetically map the resistance genes using microsatellite (SSR) markers. A population was produced by crossing the stem rust susceptible line RL6071 with Webster. The F(2) and F(3) were tested with TPMK, a stem rust race native to North America. The F(3) was also tested with TTKSK. Two independently assorting genes were identified in RL6201. Resistance to TPMK was conferred by Sr30, which was mapped with microsatellites on chromosome 5DL. The second gene, temporarily designated SrWeb, conferred resistance to TTKSK. SrWeb was mapped to chromosome 2BL using SSR markers. Comparison with previous genetic maps showed that SrWeb occupies a locus near Sr9. Further analysis will be required to determine if SrWeb is a new gene or an allele of a previously identified gene.
[Show abstract][Hide abstract] ABSTRACT: Oat (Avena sativa L.) is an important cereal crop grown world-wide for human and livestock consumption. Oat production can be adversely challenged by major diseases such as crown rust and stem rust. Race-specific seedling resistance genes are the primary means of controlling crown and stem rust of oat in Canada. Many race-specific resistance genes have been mapped and markers that are closely linked to them have been identified. However, the use of these markers in oat breeding has been limited by the economics of marker-assisted selection (MAS). The primary objective of this study was to develop markers linked to Pc91 and Pc94 for deployment in high throughput marker-assisted selection in oat breeding programs. A KASPar assay was developed from a previously reported DArT marker that co-segregated with Pc91. The KASPar assay accurately postulated the Pc91 status of 16 North American oat breeding lines. The assay was validated on four populations segregating for Pc91 which was subsequently implemented in an oat marker-assisted breeding program. This is the first report of localization of the crown rust resistance gene Pc91 to the oat chromosome 3C. Following this successful work, economical marker assays are being developed for crown rust resistance gene Pc94, stem rust resistance gene Pg13, and for resistance to stem rust race NA67.
International Plant and Animal Genome Conference XXI 2013;