Durum wheat and septoria tritici blotch: genes and prospects for breeding

Aouini, Lamia

doi:10.18174/443719

“…At present, our understanding of the genetics and molecular basis of STB resistance in durum wheat is limited. However, this situation may improve with the recent studies on Ethiopian durum wheat landraces (Kidane et al ., 2017), Tunisian landraces (Aouini, 2018), and the publication of the fully assembled durum wheat genome (Maccaferri et al ., 2019).…”

Section: Introductionmentioning

confidence: 99%

Improved control of septoria tritici blotch in durum wheat using cultivar mixtures

M’Barek

¹

,

Karisto

²

,

Abdedayem

³

et al. 2020

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Mixtures of cultivars with contrasting levels of resistance can suppress infectious diseases in wheat, as demonstrated in numerous field experiments. Most studies focus on airborne pathogens in bread wheat, while splash‐dispersed pathogens have received less attention, and no studies have been conducted in durum wheat. We conducted a 2‐year field experiment in Tunisia to evaluate the performance of cultivar mixtures with varying proportions of resistance (0%–100%) in controlling the polycyclic, splash‐dispersed disease septoria tritici blotch (STB) in durum wheat. To measure STB severity, we used a high‐throughput method based on digital image analysis of 3,074 infected leaves collected from 42 and 40 experimental plots during the first and second years, respectively. This allowed us to quantify pathogen reproduction on wheat leaves and to acquire a large data set that exceeds previous studies with respect to accuracy and precision. Our analyses show that introducing only 25% of a disease‐resistant cultivar into a pure stand of a susceptible cultivar provides a substantial reduction of almost 50% in disease severity compared to the susceptible pure stand. However, incorporating two resistant cultivars instead of one did not further improve disease control, contrary to predictions of epidemiological theory. Susceptible cultivars can be agronomically superior to resistant cultivars or be better accepted by growers for other reasons. Hence, if mixtures with only a moderate proportion of the resistant cultivar provide a similar degree of disease control as resistant pure stands, as our analysis indicates, such mixtures are more likely to be accepted by growers.

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“…Tunisian durum wheat landraces have been reported to exhibit valuable sources of resistance to STB, useful to include in breeding programs and to develop varieties with durable and broad spectrum of resistance [21,56,57]. In the present study, the 366 genotyped durum wheat accessions were also screened for Z. tritici resistance, under eld conditions, using two Z. tritici isolates Tun06 and TM220 collected from two Tunisian regions, Bizerte and Manouba, respectively.…”

Section: Genetic Distribution Of the Resistance Of Z Tritici In The Tunisian Durum Wheat Populationsmentioning

confidence: 99%

“…The introduction of the modern cultivar 'Karim' in 1980 displaced the cultivation of landraces, resulting in a reduction of the genetic diversity (genetic erosion) and therefore, enhancing the susceptibility to STB [54,55]. Durum wheat landraces, characterized by a substantial level of genetic diversity [20,22,32], represent the main sources of resistance to Z. tritici to be incorporated into breeding programs for a sustainable STB disease control and management [21,56,57]. The present study consisted on a) analyzing the genetic structure of 366 Tunisian durum wheat accessions belonging to 13 landraces using 286 single nucloetoide polymorphic markers (SNPs), b) evaluating the resistance of these accessions to two durum-wheat derived Z. tritici isolates (Tun06 and TM220) and, c) relating genotyping and disease screening data of the Tunisian durum wheat accessions to describe the life history of STB resistance in local durum wheat landraces.…”

Section: Introductionmentioning

confidence: 99%

SNP-Based Genetic Structure of Tunisian Durum Wheat Landraces and Distribution of the Resistance to Septoria Tritici Blotch

Ouaja

¹

,

Bahri²,

Ferjaoui

³

et al. 2021

Preprint

0

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Background: Septoria tritici blotch (STB) has marked durum wheat production worldwide. This fungal disease is until today a challenge for farmers, researchers and breeders all united in the aim of reducing its damage and improving wheat resistance. Tunisian durum wheat landraces were reported to be valuable genetic resources for resistance to biotic and abiotic stresses and are therefore prominently deployed in breeding programs to develop new varieties adapted to fungal diseases as STB and to climate change constraints overall.Results: 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. Conclusions: This study revealed the population structure and the genetic distribution of the resistance to Z. tritici in the Tunisian durum wheat landraces. The grouping pattern of accessions appear to be associated, to some extent, with the geographical pattern of the landraces. We suggested that GS2 accessions were mostly introduced 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 suscpetible Azizi and Jneh Khotifa accessions.

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“…Genetic distribution of the resistance of Z. tritici in the Tunisian durum wheat populations Tunisian durum wheat landraces have been reported to exhibit valuable sources of resistance to STB, useful to include in breeding programs and to develop varieties with durable and broad spectrum of resistance [21,56,57]. In the present study, the 366 genotyped durum wheat accessions were also screened for Z. tritici resistance, under eld conditions, using two Z. tritici isolates Tun06 and TM220 collected from two Tunisian regions, Bizerte and Manouba, respectively.…”

Section: Identi Cation Of a Population Structure In The Tunisian Durum Wheat Landraces Related To Their Potential Introduction Pathwaysmentioning

confidence: 99%

SNP-based Genetic Structure of Tunisian Durum Wheat Landraces and Distribution of the Resistance to Septoria Tritici Blotch

Ouaja

¹

,

Bahri²,

Ferjaoui

³

et al. 2021

Preprint

0

View full text Add to dashboard Cite

Background: Septoria tritici blotch (STB) has marked durum wheat production worldwide. This fungal disease is until today a challenge for farmers, researchers and breeders all united in the aim of reducing its damage and improving wheat resistance. Tunisian durum wheat landraces were reported to be valuable genetic resources for resistance to biotic and abiotic stresses and are therefore prominently deployed in breeding programs to develop new varieties adapted to fungal diseases as STB and to climate change constraints overall.Results: 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. Conclusions: This study revealed the population structure and the genetic distribution of the resistance to Z. tritici in the Tunisian durum wheat landraces. The grouping pattern of accessions appear to be associated, to some extent, with the geographical pattern of the landraces. We suggested that GS2 accessions were mostly introduced 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 suscpetible Azizi and Jneh Khotifa accessions.

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Durum wheat and septoria tritici blotch: genes and prospects for breeding

Cited by 9 publications

References 122 publications

Improved control of septoria tritici blotch in durum wheat using cultivar mixtures

Improved control of septoria tritici blotch in durum wheat using cultivar mixtures

SNP-Based Genetic Structure of Tunisian Durum Wheat Landraces and Distribution of the Resistance to Septoria Tritici Blotch

SNP-based Genetic Structure of Tunisian Durum Wheat Landraces and Distribution of the Resistance to Septoria Tritici Blotch

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