Department of agronomy and plant biotechnology, Laboratory of genetics and cereal breeding (LR14AGR01), The National Agronomic Institute of Tunisia (INAT), University of Carthage, 43 Avenue Charles-Nicolle, Tunis, 1082, Tunisia.
Department of Plant Pathology, Institute of Plant Breeding, Genetics and Genomics, University of Georgia, Griffin, GA, 30223, USA.
BMC Genomics. 2023 Jun 15;24(1):328. doi: 10.1186/s12864-023-09395-1.
Septoria tritici blotch (STB) remains a significant obstacle to durum wheat cultivation on a global scale. This disease remains a challenge for farmers, researchers, and breeders, who are collectively dedicated to reduce its damage and improve wheat resistance. Tunisian durum wheat landraces have been recognized as valuable genetic ressources that exhibit resistance to biotic and abiotic stresses and therefore play a crucial role in breeding program aimed at creating new wheat varieties resistant to fungal diseases as STB, as well as adapted to climate change constraints.
A total of 366 local durum wheat accessions were assessed for resistance to two virulent Tunisian isolates of Zymoseptoria tritici Tun06 and TM220 under field conditions. Population structure analysis of the durum wheat accessions, performed with 286 polymorphic SNPs (PIC > 0.3) covering the entire genome, identified three genetic subpopulations (GS1, GS2 and GS3) with 22% of admixed genotypes. Interestingly, all of the resistant genotypes were among GS2 or admixed with GS2.
This study revealed the population structure and the genetic distribution of the resistance to Z. tritici in the Tunisian durum wheat landraces. Accessions grouping pattern reflected the geographical origins of the landraces. We suggested that GS2 accessions were mostly derived from eastern Mediterranean populations, unlike GS1 and GS3 that originated from the west. Resistant GS2 accessions belonged to landraces Taganrog, Sbei glabre, Richi, Mekki, Badri, Jneh Khotifa and Azizi. Furthermore, we suggested that admixture contributed to transmit STB resistance from GS2 resistant landraces to initially susceptible landraces such as Mahmoudi (GS1), but also resulted in the loss of resistance in the case of GS2 susceptible Azizi and Jneh Khotifa accessions.
小麦叶枯病（STB）仍然是全球范围内硬质小麦种植的重大障碍。这种疾病仍然是农民、研究人员和育种者面临的挑战，他们共同致力于减少其危害并提高小麦的抗性。突尼斯硬质小麦地方品种被认为是具有生物和非生物胁迫抗性的宝贵遗传资源，因此在旨在创造新的小麦品种以抵抗 STB 等真菌病害以及适应气候变化限制的育种计划中发挥着至关重要的作用。
在田间条件下，对 366 份当地硬质小麦品系进行了对两个毒力强的突尼斯 Zymoseptoria tritici Tun06 和 TM220 分离株的抗性评估。对 286 个多态性 SNP（PIC>0.3）覆盖整个基因组的硬质小麦品系进行的群体结构分析，鉴定出 3 个遗传亚群（GS1、GS2 和 GS3），其中 22%为混合基因型。有趣的是，所有抗性基因型都属于 GS2 或与 GS2 混合。
本研究揭示了突尼斯硬质小麦地方品种中对 Z. tritici 的群体结构和遗传分布。品系分组模式反映了地方品种的地理起源。我们认为，GS2 品系主要来自东地中海种群，而 GS1 和 GS3 则来自西部。抗性 GS2 品系属于 Taganrog、Sbei glabre、Richi、Mekki、Badri、Jneh Khotifa 和 Azizi 等地方品种。此外，我们认为，混合有助于将 GS2 抗性地方品种的 STB 抗性传递给最初易感的地方品种，如 Mahmoudi（GS1），但也导致 GS2 易感的 Azizi 和 Jneh Khotifa 品系丧失抗性。
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