Abstract
Durum wheat landraces have huge potential for the identification of genetic factors valuable for improving resistance to biotic stresses. Tunisia is known as a hot spot for Septoria tritici blotch disease (STB), caused by the fungus Zymoseptoria tritici (Z. tritici). In this context, a collection of 3166 Mediterranean durum wheat landraces were evaluated at the seedling and adult stages for STB resistance in the 2016–2017 cropping season under field conditions in Kodia (Tunisia). Unadapted/susceptible accessions were eliminated to reach the final set of 1059 accessions; this was termed the Med-collection, which comprised accessions from 13 countries and was also screened in the 2018–2019 cropping season. The Med-collection showed high frequency of resistance reactions, among which over 50% showed an immune reaction (HR) at both seedling and adult growth stages. Interestingly, 92% of HR and R accessions maintained their resistance levels across the two years, confirming the highly significant correlation found between seedling- and adult-stage reactions. Plant Height was found to have a negative significant effect on adult-stage resistance, suggesting that either this trait can influence disease severity, or that it can be due to environmental/epidemiological factors. Accessions from Italy showed the highest variability, while those from Portugal, Spain and Tunisia showed the highest levels of resistance at both growth stages, suggesting that the latter accessions may harbor novel QTLs effective for STB resistance.
Highlights
Durum wheat is an important crop in the Mediterranean basin that has been cultivated over centuries and under widely variable climatic conditions
The objectives of this study were to evaluate a sub-set of Mediterranean durum wheat landraces, mainly originating from Algeria, France, Italy, Portugal, Spain and Tunisia, for resistance to Z. tritici under field conditions at seedling and adult stages
The integrated field seedling and adult plant phenotyping method reported in this study provides a great tool for identifying novel and durable resistance sources
Summary
Durum wheat is an important crop in the Mediterranean basin that has been cultivated over centuries and under widely variable climatic conditions. Multiple invasions that have occurred in the region, the migration of wheat from the east to the west of the Mediterranean basin, wheat imports, and natural and human selection are other important factors that contributed to its diversification (Mercer and Perales, 2010). This vast biodiversity within the species [4] extends to the vast array of homemade foods derived from durum grains. Due to their high protein content and gluten strength, cultivars of durum wheat are preferred to produce semolina for use as pasta products, couscous, and bulgur [1,5]. Mediterranean durum wheat landraces have been, and continue to be, a great source of novel useful genes that could be further exploited by breeders
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