Microsatellite analysis of selected Puccinia triticina races in South Africa

Abstract

Microsatellite analysis of ten South African races of Puccinia triticina, the causal organism of leaf rust of wheat (Triticum aestivum), divided the population into two groups sharing 32% genetic similarity. In the first group, race 3SA145 (Agricultural Research Council notation) clustered with 3SA122 and 3SA125, two races that have not been detected recently. This grouping was supported by avirulence for Lr1 in all three races. The second group included the current dominant race 3SA133, that shared 42% genetic homology with the remaining six races. Five of these, including 3SA144, formed a sub-group with 96% genetic homology amongst them. It was concluded that 3SA144, detected on triticale in 2005 and virulent for Lr32, probably represents a mutation from an existing race, whereas 3SA145 most likely was an exotic introduction. Race 3SA145 was first detected in 2009 and differed from known races in terms of combined virulence for the adult-plant resistance genes Lr12, Lr13 and Lr37. Microsatellite analysis complemented traditional phenotypic characterization of P. triticina and provided insight on genetic relationships amongst older and more recently detected races in South Africa.

Response of an International Triticale Collection toPuccinia triticinaandPuccinia reconditasensu stricto and Assessment of Temperature Sensitivity in Leaf Rust Isolates

“…The higher virulence found for 3SA144 (SDDN), collected from triticale in the Western Cape SA during 2005, towards the international and local set of triticale germplasm entries is in strong support with earlier findings of increased virulence for this Pt race towards triticale (Pretorius and Bender 2010). Using microsatellite analyses, Visser et al (2011) found that 3SA144, with added virulence for Lr32, is closely related to four other South African Pt races, namely 3SA132 (SDDJ), 3SA134 (SBD), 3SA137 (SCDS) and 3SA140 (SFDS). Race 3SA145 collected from wheat during the 2009 rust survey season was the first South African Pt race with virulence for Lr37 combined with virulence for Lr12 and Lr13 (Terefe et al 2011).…”

“…Race 3SA145 collected from wheat during the 2009 rust survey season was the first South African Pt race with virulence for Lr37 combined with virulence for Lr12 and Lr13 (Terefe et al 2011). Based on results from microsatellite analyses as well as the avirulence/virulence profile of 3SA145 and the similarity of the latter with other international leaf rust races, Visser et al (2011) did not exclude the possibility of 3SA145 being an exotic introduction into SA. The avirulence/virulence profile of 3SA248 and supportive microsatellite analyses strongly support the development of this race from 3SA145 (Boshoff et al 2018).…”

“…Despite the initial characterisation of 3SA144, its pathogenicity on diverse triticale germplasm has never been determined. It would also be useful to establish whether the newly identified wheat leaf rust race 3SA248 which attacks Lr26, shows increased virulence towards triticale when compared to the older but genetically related race 3SA145 (Terefe et al 2011;Visser et al 2011;Boshoff et al 2018).…”

Pathogenic and genetic diversity ofPuccinia triticinafrom triticale in Poland between 2012 and 2015

“…tritici (Zhang et al, 2010) that are adapted to triticale have been detected. Based on microsatellite analysis, Visser et al (2012) concluded that a race of P. triticina isolated from triticale probably arose via mutation in an existing race. According to Hovmøller et al (2016), an aggressive race of P. striiformis f. sp.…”

Accomplishments in wheat rust research in South Africa

“…The current South African Pt population consists of two primary genetic lineages 20 , but at least five were evident according to Pt isolates collected during the previous century 49 . Three of these appear to be extinct while only one lineage is expanding.…”