Wheat Stem Rust Detection and Race Characterization in Tunisia

Abstract

Climate changes over the past 25 years have led to conducive conditions for invasive and transboundary fungal disease occurrence, including the re-emergence of wheat stem rust disease, caused by Puccinia graminis f.sp. tritici (Pgt) in East Africa, Europe, and the Mediterranean basin. Since 2018, sporadic infections have been observed in Tunisia. In this study, we investigated Pgt occurrence at major Tunisian wheat growing areas. Pgt monitoring, assessment, and sampling from planted trap nurseries at five different locations over two years (2021 and 2022) revealed the predominance of three races, namely TTRTF (Clade III-B), TKKTF (Clade IV-F), and TKTTF (Clade IV-B). Clade III-B was the most prevalent in 2021 as it was detected at all locations, while in 2022 Pgt was only reported at Beja and Jendouba, with the prevalence of Clade IV-B. The low levels of disease incidence during these two years and Pgt population diversity suggest that this fungus most likely originated from exotic incursions and that climate factors could have caused disease establishment in Tunisia. Further evaluation under the artificial disease pressure of Tunisian wheat varieties and weather-based modeling for early disease detection in the Mediterranean area could be helpful in monitoring and predicting wheat stem rust emergence and epidemics.

Characterization of Wheat Yellow Rust and Stem Rust Virulence in Southern Spain

“…Based on the off-season field readings from this study and DNA analysis at the GRRC, the predominant groups present during the current study were Clade IV-B (TKKTF) and Clade IV-F (TKTTF) [38]. As reported by Abdedayem et al [48], stem rust has recently reappeared in many parts of Europe, and Clade IV-B and Clade IV-F were found to be present in Spain, Italy, France, Morocco, and Tunisia. The presence of the Sicilian TTRTF race in southern Spain and during the present study was considered improbable as this race is virulent on Sr13 [49], and the line harboring Sr13 was always resistant (partial resistance) over the duration of this study.…”

Genome-Wide Identification and Expression Profiling of Pathogenesis-Related Protein 1 (PR-1) Genes in Durum Wheat (Triticum durum Desf.)

“…Durum wheat (Tunisian varieties) is also resistant to the wheat stem rust disease caused by Puccinia graminis f.sp. tritici [ 46 ] and to the cereal cyst nematode attack via the (TRITD2Av1G265560) gene, a potential candidate for improving wheat resistance to nematode infections [ 47 ].…”