Towards a comprehensive characterization of durum wheat landraces in Moroccan traditional agrosystems: analysing genetic diversity in the light of geography, farmers’ taxonomy and tetraploid wheat domestication history

Background: Crop diversity managed by smallholder farmers in traditional agrosystems is the outcome of historical and current processes interacting at various spatial scales, and influenced by factors such as farming practices and environmental pressures. Only recently have studies started to consider the complexity of these processes instead of simply describing diversity for breeding purposes. A first step in that aim is to add multiple references to the collection of genetic data, including the farmers' varietal taxonomy and practices and the historical background of the crop. Results: On the basis of interview data collected in a previous study, we sampled 166 populations of durum wheat varieties in two traditional Moroccan agrosystems, in the Pre-Rif and Atlas Mountains regions. Using a common garden experiment, we detected a high phenotypic variability on traits indicative of taxonomical position and breeding status, namely spike shape and plant height. Populations often combined modern (short) with traditional-like (tall) statures, and classical durum squared spike shape (5 flowers/spikelet) with flat spike shape (3 flowers/spikelet) representative of primitive domesticated tetraploid wheat (ssp. dicoccum). By contrast, the genetic diversity assessed using 14 microsatellite markers was relatively limited. When compared to the genetic diversity found in a large collection of tetraploid wheat, it corresponded to free-threshing tetraploid wheat. Within Morocco, the two studied regions differed for both genetic diversity and variety names. Within regions, neither geography nor variety names nor even breeding status constituted strong barriers to gene exchange despite a few significant patterns. Conclusions: This first assessment of morphological and genetic diversity allowed pointing out some important factors that may have influenced the structure and evolutionary dynamics of durum wheat in Morocco: the significance of variety names, the occurrence of mixtures within populations, the relative strength of seed exchange between farmers and local adaptation, as well as the fate of modern varieties once they have been introduced. Further, multidisciplinary studies at different spatial scales are needed to better understand these complex agrosystems of invaluable importance for food security

Impact du relief et des circuits semenciers locaux sur la diversité agro-morphologique du blé dur (Triticum turgidum ssp. durum) dans la vallée d'Er Rich à Imilchil (Maroc)

Phenotypic diversity of 101 durum wheat landrace populations collected from the oasis of the Oriental Atlas Mountains (Morocco) was studied. Nine characters (morphological and agronomic) were measured on the 3030 lines (30 lines per population). The frequencies of each phenotypic class were used for the estimate and the analysis of diversity, by considering the geographical zones of origin and the gradients of altitude. The Shannon-Weaver diversity index (H’) showed a wide variability for all considered traits. This index varies from one area to another and from one altitudinal class to another. The mean H’ recorded for all areas was 0.62, indicating the presence of a high degree of polymorphism among the studied durum wheat landrace populations. The results of the multiple component analysis and the hierarchical clustering showed that the geographical proximity and altitude play a main function in the discrimination and the structure of the studied durum wheat populations. The information gathered from this study could be used in conventional breeding programs and in situ conservation of the diversity. La diversité phénotypique de 101 populations locales de blé dur issues des oasis de montagnes de l’Atlas oriental (Maroc) a été étudiée. Neuf caractères (morphologiques et agronomiques) ont été mesurés sur les 3030 lignées (30 lignées par population). Les fréquences de chaque classe phénotypique ont été utilisées pour l’estimation et l’analyse de la diversité, en considérant les zones géographiques d’origine et les gradients d’altitude. L’indice de diversité de Shannon-Weaver (H’) a montré une forte variabilité pour l’ensemble des caractères considérés. Cet indice varie d’une zone à une autre et d’une classe d’altitude à une autre. Le H’ moyen obtenu pour l’ensemble des zones est de 0,62, indiquant la présence d’un degré élevé de polymorphisme au sein des populations locales de blé dur collectées. Les résultats de l’analyse en composantes multiples ainsi que de la classification hiérarchique ont montré que la proximité géographique et l’altitude jouent un rôle majeur dans la discrimination ainsi que sur la structuration des populations de blé dur étudiées. Les informations recueillies à partir de ces résultats peuvent être exploitées dans des programmes de sélection conventionnels et de conservation in situ de la diversité. Mots clés: Populations locales, diversité phénotypique, structuration, conservation in situ, blé dur (Triticum turgidum ssp. durum)

Impact du relief et des circuits semenciers locaux sur la diversité agro-morphologique du blé dur (Triticum turgidum ssp. durum) dans la vallée d’Er Rich – Imilchil (Maroc)

Phenotypic diversity of 101 durum wheat landrace populations collected from the oasis of the Oriental Atlas Mountains (Morocco) was studied. Nine characters (morphological and agronomic) were measured on the 3030 lines (30 lines per population). The frequencies of each phenotypic class were used for the estimate and the analysis of diversity, by considering the geographical zones of origin and the gradients of altitude. The Shannon-Weaver diversity index (H’) showed a wide variability for all considered traits. This index varies from one area to another and from one altitudinal class to another. The mean H’ recorded for all areas was 0.62, indicating the presence of a high degree of polymorphism among the studied durum wheat landrace populations. The results of the multiple component analysis and the hierarchical clustering showed that the geographical proximity and altitude play a main function in the discrimination and the structure of the studied durum wheat populations. The information gathered from this study could be used in conventional breeding programs and in situ conservation of the diversity

Anchoring durum wheat diversity in the reality of traditional agricultural systems: varieties, seed management, and farmers’ perception in two Moroccan regions

Background: Traditional agrosystems are the places were crop species have evolved and continue to evolve under a combination of human and environmental pressures. A better knowledge of the mechanisms underlying the dynamics of crop diversity in these agrosystems is crucial to sustain food security and farmers’ self-reliance. It requires as a first step, anchoring a description of the available diversity in its geographical, environmental, cultural and socio-economic context. [br/] Methods: We conducted interviews with farmers cultivating durum wheat in two contrasted traditional agrosystems of Morocco in the Pre-Rif (163 farmers) and in the oases of the Atlas Mountains (110 farmers). We documented the varietal diversity of durum wheat, the main characteristics of the farms, the farming and seed management practices applied to durum wheat, and the farmers’ perception of their varieties. [br/] Results: As expected in traditional agrosystems, farmers largely practiced diversified subsistence agriculture on small plots and relied on on-farm seed production or informal seed exchange networks. Heterogeneity nevertheless prevailed on many variables, especially on the modernization of practices in the Pre-Rif region. Fourteen (resp. 11) traditional and 5 (resp. 3) modern varieties were identified in the Pre-Rif region (resp. in the Atlas Mountains). The majority of farmers grew a single variety, and most traditional varieties were distributed in restricted geographical areas. At the farm level, more than half of the varieties were renewed in the last decade in the Pre-Rif, a more rapid renewal than in the Atlas Mountain. Modern varieties were more prevalent in the Pre-Rif region and were integrated in the traditional practices of seed production, selection and exchange. They were clearly distinguished by the farmers from the landraces, the last ones being appreciated for their quality traits. [br/] Conclusions: The surveyed traditional agrosystems constitute open, dynamic and heterogeneous entities. We suggest that competing factors could favour or limit the cultivation of improved varieties and the erosion of original durum wheat diversity. This first description opens the way to focused further investigations, including complementing variety names with cultural, genetic and phenotypic information and unravelling the multidimensional factors and consequences of modern variety adoption

Diversité agro-morphologique et gestion variétale par les agriculteurs du blé dur (Triticum turgidum ssp. durum) dans le Pré-Rif marocain

Le blé dur est une culture stratégique au Maroc. La caractérisation et l’évaluation des variétés cultivées dans différents agro-écosystèmestraditionnels permettent la sauvegarde et la réhabilitation de ce patrimoine génétique ainsi que son utilisation dans desprogrammes de sélection. Dans ce contexte, une collection de 59 populations traditionnelles de blé dur issues de la région du Pré-Rif a été étudiée en utilisant neuf traits agro-morphologiques. La diversité phénotypique a été déterminée par l’indice de diversitéShannon-Weaver (H’) à différents niveaux (Totalité de l’échantillon, par typologie du blé et par nom variétal). Les H’ estimés ontmontré une large variabilité phénotypique pour les différents traits avec un H’ moyen de 0,78. Les résultats de l’analyse des correspondancesmultiples et de la classification hiérarchique ont montré une nette distinction entre les variétés modernes et traditionnelles.Les caractères agro-morphologiques ne permettent pas de différencier les variétés traditionnelles entre elles. Les résultats de ce travailont permis de révéler la grande diversité phénotypique des variétés de blé dur qui ne correspond que partiellement aux noms desvariétés du fait de l’existence d’homonymes et de synonymes dans les noms donnés par les agriculteurs.Durum wheat is a strategic crop in Morocco. Characterization and evaluation of cultivated varieties in different traditional agroecosystemsallows safeguard and rehabilitation of this genetic heritage and its use in breeding programs. In this context, a collectionof 59 traditional populations of durum wheat from the Pre-Rif region was studied using nine agro-morphological traits. Phenotypicdiversity was determined by the Shannon-Weaver diversity index (H’) at different levels (totality of sample, by type of wheat andvarietal names). Estimated H’ showed a wide genetic variability for different traits with a mean of H’=0.78. The results of the multiplecorrespondence analysis and hierarchical clustering showed a clear distinction between modern and traditional varieties. In traditionalvarieties, agro-morphological traits do not differentiate between varieties. The results of this work revealed the great phenotypic andnominative diversity of durum wheat varieties as well as the existence of homonyms and synonyms in the names given by farmers

Platelet reactivity to thrombin differs between patients with COVID-19 and those with ARDS unrelated to COVID-19.

In addition to preserving homeostasis and contributing to immunity, platelets may exhibit a dysregulated state in acute respiratory distress syndrome (ARDS), and potentially exacerbate lung injury. Although thrombocytopenia has been associated with increased mortality in ARDS and particularly in H1N1 influenza-infected patients, analysis of quantitative changes in platelet activation levels in ARDS, and how these may differ between the various etiologies of ARDS remains limited.non