A shared collection (SC) of plant materials has been proposed for employment in various IMPRESA work packages (WPs). While the experimental set of materials may change in the course of the project, on the basis of inputs (observations, results) from project participants, and be more specifically shaped to respond to given environments, the initial SC included:
1. Durum wheat (DW) varieties cultivated in the different participant countries (provided by all participants), chosen for their tolerance towards various stresses (as from previous observations of good performance at the regional/country level), as well as for yield performance in stressed environments. Some DW land races, adapted to Turkish environments, are also part of this set (48 entries).
2. DW-alien recombinants (12 lines + controls), with stably introgressed alien chromosome segments (produced by P0-UNITUS by chromosome engineering), containing several resistance genes to common diseases throughout Mediterranean environments (e.g., rusts, Fusarium head blight and crown rot), quality and yield-related traits. In their pedigree, Italian, Tunisian and ICARDA’s elite DW lines are involved. Several of these entries consist of DW-WWR near-isogenic recombinant lines (NIRLs), suited for targeted differential analyses (e.g., WP1, 2, 3). A set of NIRLs involves DW chromosome arms 7AL and Th. ponticum 7el1L, the latter shown to contain yield-related genes/QTL enhancing spike fertility under both mild environmental conditions (Kuzmanovic et al. 2016, Field Crops Res. 186: 86–98) and stressful environmental conditions (Kuzmanovic et al. 2018, Field Crops Res. 228: 147–15.), besides that several other useful traits. In other recombinant lines, besides the Th. ponticum 7el1L-derived genes, additional beneficial genes have been pyramided in the same alien segment, as in the case of the 7el1L + 7EL assembly. In the latter, the 7EL segment contains a major QTL conferring outstanding resistance to Fusarium diseases (Ceoloni et al. 2017, Theor. Appl. Genet. 130: 2005-2024). Interestingly, 7EL genes were shown to contribute to salt tolerance (e.g., Deal et al. 1999, Euphytica 108: 193). For all the DW-alien recombinants, molecular markers associated to the alien segment(s) introgressed into DW are available for molecular-assisted (MAS) breeding (WP5), and their use will be further optimized in the course of the project. All DW-alien recombinant lines, homozygous for the respective alien introgression, are in advanced self-generations, hence they are largely stable in the overall phenotype.
3. DW-WWRs amphiploids (16 entries). In them, the DW genome is combined with that of wild wheat relatives (WWRs), including several Aegilops spp. and more distant genera from Triticum, like Thinopyrum or Haynaldia (= Dasypyrum). These come from, and in several cases are still growing in the near East and part of North Africa, where several Triticeae species originated, but also occur in Turkey, East Europe, and even extend into Central Asia and the Sahara-Arabian region. Their habitats encompass a wide range of annual rainfall amplitude, in several cases touching minimums of less than 100 mm (e.g. Aegilops longissima, Ae. kotschyi, Ae. triuncialis), temperature regimes, largely different soil types (often sandy, shallow-rocky, salty) and altitudes (from the sea level to over 2000 m a.s.l.). Hence, they have a great potential for providing genes/QTL enhancing DW tolerance to an array of abiotic stresses, which will be “accessed” by “chromosome engineering”/“introgressiomic” approaches (WP5). To this regard, some of the amphiploids are in Ph1-lacking genetic background, hence their progeny is already the product of wheat-alien chromosome recombination; others possess common genomes to those of DW; hence, also in this case recombination in the course of breeding activity (WP5) will encounter no barrier.
For several materials, prior knowledge of their reaction to frequently occurring diseases across environments is available, with many of the recombinant and amphiploid types resulting good sources of resistance to single or multiple pathogens attacking the above- and below-ground parts of the plant (see above). Some information of yield performance in individual locations also exists, revealing the need for breeding interventions (notably in Algeria and to some extent Tunisia as well), where breeding strategies need a significant leap to meet the country’s demand (e.g., Abdelkader, 2014, Options Medit., Série A. Sémin. Médit. 110: 363). Much less is known about the materials’ potential for tolerance to abiotic stresses, except for contingent/regional cases, and the mechanisms underlying plant response to stress conditions and their genetic control, particularly in largely unexplored and untapped resources to this regard, await for elucidation and harnessing.