IMPRESA - IMProving RESilience to Abiotic stresses in durum wheat: enhancing knowledge by genetic, physiological and “omics” approaches and increasing Mediterranean germplasm biodiversity by crop wild relatives-based introgressiomics

Nowadays, in the face of population growth, rapidly evolving societal behaviour (including consumption habits, particularly in developing countries), increasing demand and pressure on shrinking resources (mainly land and water), and unpredictable effects of climate changes, a new paradigm for agricultural production is required to ensure food security and safety. Moreover, the adequate and diversified measures to be adopted will have to be environmentally sustainable. In crop plants, generations of selection by breeders and farmers have led to great changes in cereals such as wheat when compared to their undomesticated ancestors. Although crop improvement is dependent upon genetic diversity, strategies of agricultural intensification followed, in particular, in the recent past (as in the course of the last century “Green revolution”), have had, alongside highly positive outcomes, negative implications for the extant genetic variation. In fact, crop varieties adapted to the diversity of environmental conditions existing in an area prior to its coming under industrial agriculture have been overtaken by new, high-input and high-yielding types, and in most cases eventually lost. As a result, relatively “old” varieties, generally lower yielding than more modern ones, and yet well adapted to regional constraints, have been dismissed, with consequent loss of their adaptive traits. This is the case, e.g., for the drought tolerant Tunisian cvs. Karim and Om Rabia (also salt tolerant) compared to recent cvs. Maali and Salim (Slama et al., 2018, DOI: 10.1371/journal.pone.0196873). On the other hand, traditionally farmed varieties may not keep up with rapidly deteriorating environmental conditions, as in Algeria, where climate projections anticipate conspicuous increases in temperature throughout the year and a net decrease in precipitation (Chourghal et al., 2016, DOI 10.1007/s10113-015-0889-8). All these situations point at the need for strengthening the efforts and giving a different speed and “cut” to the regional breeding programs, which will have to retain and valorize adaptive traits from old germplasm, while introducing new and effective variability to make a step forward the new challenges and the achievement of more stable and economically satisfactory yields.

For polyploid wheat, more than for other important but diploid cereal crops (rice and maize), the application of the most forefront genome manipulations, such as genome editing, is still in its infancy, and with more unpredictable outcomes due to gene duplication in the different sub-genomes. On the other hand, other unconventional approaches are readily and successfully applicable to widen the wheat genetic basis for the needed, multifaceted improvements. In fact, the rate of genetic gain in crop breeding programs can greatly increase by extending the amount and nature of variation using land races and wild crop relatives. They can be effectively exploited by use of the cytogenetic strategy of “chromosome engineering”, that allows the transfer of even small chromosomal segments from related species belonging to more or less distant gene pools of the same Triticeae tribe. The greatest part of this large group of species are a wide array of wild wheat relatives (WWRs) that share with cultivated wheat a large part of their gene content (synteny), yet with the respective allelic variants being rather differentiated. Nonetheless, at least regional gene synteny is the key for allowing what can be obtained by means of chromosome engineering in complete or partial wheat-alien hybrid combinations, i.e. alien (WWRs)-to-wheat gene transfer via spontaneous or genetically promoted meiotic recombination. Despite the range of undesirable traits that exotic germplasm, such as that of WWRs, is known to carry alongside beneficial traits, we can currently benefit from the great advancements enabled by the “omics revolution”, including all the necessary tools for accurate characterization and selection of desired products, from identification of genes/QTL underlying the genetic architecture of relevant traits, to high-throughput phenotyping as well as molecular marker technologies. With all these tools available, access to the still poorly exploited gene pools of WWRs has become feasible as ever before. WWRs are equipped with inherent resilience to a variety of harsh environments, but also with a wealth of unpredictable or only recently uncovered and valued positive effects on wheat yield and quality-related traits. All such valuable traits, lacking in cultivated wheat germplasm, can be being increasingly targeted in a variety of “smart breeding” paths. One of the main pillars of the IMPRESA project is the use, production and throughout characterization of wheat (mainly durum wheat, DW) lines containing portions of variable amount of genetic information from related species (WWRs). These genetic materials (including cultivated varieties, land races, recombinant and amphidiploid lines) will be shared among partners, hence tested in very different environmental conditions, typically affected by often multiple stresses, and also assayed for single or combined stresses (mainly abiotic stresses such as heat, drought and salinity) under controlled conditions. The natural and induced stress response of plant materials will be monitored through its morpho-physiological, biochemical/metabolic, as well as agronomic/yield components, and some of the most relevant genetic and chromosomal determinants targeted for in-depth analyses. The resulting knowledge, besides its intrinsic scientific value, particularly for little explored genetic materials like DW, WWRs and their introgression products, will be used for the enhancement of DW breeding programs in the participant countries. This "from lab to field" strategy aims at the introduction of novel traits of adaptive and production value into local germplasm, thus maintaining the valuable, local biodiversity and at the same time, reinforce it with “new blood” from other sources.

IMPRESA is expected to contribute to enhance knowledge of the way cultivated wheat, particularly DW, and its wild relatives interact with the environment and improve breeding effectiveness within Mediterranean countries where heat, drought and salinity, in combination with biotic stresses and other challenges, are major challenges to crop yield and stability. A summary list of specific expected impacts includes: 1. Exploitation of genetic diversity of wild wheat relatives to enhance tolerance of DW cultivars to stress conditions; 2. Increased knowledge of physiological, metabolic and genetic mechanisms of plant response to major abiotic stresses affecting the Mediterranean area, focusing on durum wheat (DW), its main cereal crop, and having major impacts on its yield potential; 3. Translation of results from laboratory to field, i.e. application of molecular-, physiological- and “omics”-based crop improvement strategies for the development of stress-resilient DW cultivars; 4. Wider engagement and awareness of project partners (and through them potentially of local stakeholders), about the advantages of the project strategies, addressing in particular DW-WWRs “chromosome engineering” and highlighting how this approach compares with “traditional breeding” versus GMO technologies to improve crops, especially in view of maximizing valorisation of natural biodiversity; 5. Implementation of cooperative/participatory approaches into the breeding pipeline. To this regard, one example is the Conservation Agriculture practice of “no-till”, having a well rooted tradition in Algeria, one of the partner countries (in 2005, created a “Trait d’union” association for the development of sustainable and environmentally friendly agriculture, bringing together researchers, technicians, producers and farmers, see, e.g. https://docplayer.fr/25305571-L-experience-de-l-agriculture-de-conservation-en-algerie.html). Similarly, the water-saving system of bed planting-furrow irrigation, successfully adopted in Turkey (Kiliç 2010 Sci Res Essays 5: 3063) and elsewhere (e.g. Mexico, see Tripathi et al. 2005 Crop Sci 45:1448), will be implemented in the trials with the project genetic materials, in order to maintain diverse, sustainable farming systems, possibly “exporting” them beyond native, local environments. 6. Empowerment of new and high-potential actors towards future technological leadership: young researchers (e.g. PhDs, Post-docs, fellowship holders) hired in the project will have enhanced experience, also on a transnational level, to become high-potential actors in the future of sustainable, molecular-assisted and climate-responsive breeding of complex crop species such as DW, in leading positions either in academic/research institutes or in breeding companies. 7. Women’s Empowerment and Gender Equality: in line with the Sustainable Development Goal “Achieve gender equality and empower all women and girls” of the 2030 UN Agenda for Sustainable Development, and the FAO position on Gender Equality and Food Security: Women’s Empowerment as a Tool Against Hunger (2013), the project will promote women’s participation to the planned activities at various levels, from national and transnational enhanced experience of young researchers (training), to women participation to dissemination initiatives towards stakeholders. Some of the expected impacts are part of a medium to long-term perspective, and the project will be able to undertake and implement them, yet not to bring to full completion within the project duration (particularly the breeding activities). Yet, solid foundations for fulfilment of scientific and practical acquisitions will be laid.