New insight into the North-African durum wheat biodiversity: phenotypic variations for adaptive and agronomic traits

Unlocking the Patterns of the Tunisian Durum Wheat Landraces Genetic Structure Based on Phenotypic Characterization in Relation to Farmer’s Vernacular Name

“…Our results showed high variability between genotypes (G) for almost all the traits across the six environments (percentage of variance > 50%), except for seed total area and number of spikelets per spike (percentage of variance < 40%). In comparison to other studies, our work showed higher variability than that reported for nine agro-morphologic and three phenological traits among Tunisian durum wheat genotypes with a range of 5.38 % for heading date to 24.07 % for thousand kernel weight [26], to that reported for four agronomical traits among Tunisian and Algerian germplasm, particularly for thousand kernel weight with a value of 9.45% [19] and to that showed for fourteen agronomic and phenological traits evaluated across six environments in a large collection of Mediterranean durum wheat landraces, with the largest variation registered for plant height (78.2%) [12]. The Percentage of variance of each trait showed that the genetic patterns based on the number of sub-populations K = 6 explained more the phenotypic variability than Farmer`s population nomenclature, and the partitioning sum of squares analysis of all the traits across the six studied environments indicated a highly significant phenotypic diversity among the present Tunisian landraces (> 64.80%).…”

“…The highest heritability of the two phenological (HD and MD) and the plant height (H) traits were comparable to those reported in Ethiopian durum wheat farmers varieties and improved varieties evaluated in two zones in Northern Ethiopia for two years [45]. Our findings showed higher heritability of the agro-morphological traits, particularly for the thousand kernel weight (TKW) in comparison to those described using Ethiopian durum wheat landraces (H2 = 0.6) and a collection of Tunisian and Algerian durum germplasm (H2 = 0.53) [19,45]. Relatively similar heritability values to our findings were reported for the majority of the agronomic traits in a previous study using Chinese wheat landraces collected from different zones in China and evaluated for 23 agro-morphological traits in six environments [46].…”

“…Tunisia is considered among the secondary centers of durum wheat diversity and includes a large collection of landraces [23], which are described by several experts as a reservoir of useful genes with high allelic richness [10,24]. Previous studies reported high genetic diversity in several collections of Tunisian germplasm using agro-morphological traits [19,26]. Belhaj et al [27] described high and different levels of genetic diversity in 930 accessions collected from different localities in the South of Tunisia using twentytwo qualitative and three quantitative traits.…”

Unlocking the Patterns of the Tunisian Durum Wheat Landraces Genetic Structure Based on Phenotypic Characterization in Relation to Farmer’s Vernacular Name

“…Particularly, the Mediterranean landraces showed a higher level of polymorphism and allelic richness for some quality traits compared to those from Southwest Europe and Southwest Asia [14,15]. The West Mediterranean landraces have shown their resistance to drought [16,17] and diseases [18], their phenotypic plasticity and their adaptability to harsh environmental conditions, and low in-put farmers agro-systems [19][20][21]. However, these landraces including the Tunisian ones are continually lost, due to farmer's adoption of new high-yielding and homogenous cultivars released since the period of the Green Revolution in the 1970s, which resulted in narrowing the genetic diversity of durum wheat [10,22].…”

“…Farmer's management of these landraces has shaped the genetic diversity between and within landraces and their genetic structure. Several studies have reported high phenotypic diversity among the Tunisian durum wheat germplasm through evaluating agronomic and adaptative traits [19,26], and through phenotypic characterization based on the international standards descriptors of the International Plant Genetic Resources Institute (IPGRI) and the International Union for the Protection of New Varieties of Plants (UPOV) [26,27]. Besides the phenotypic diversity of durum wheat landraces, genetic population structure is also an important criterion to buffer the effects of climate change and biotic and abiotic stresses.…”