FACCE ERA-NET+ An integrated approach to evaluate and harvest genetic diversity for breeding climate-resilient barley

Based on studies in model plants, there is an increasing understanding of stress response and disease
resistance pathways in plants and how these pathways intersect and interact. This understanding will help
create a framework within the proposed ClimBar project in which to place the GWAS-based results and in
which to carry out GS and ideotype modelling. Environmental stresses such as heat, cold, drought, flooding
and attack by pathogens are not experienced singly; the phytohormone abscisic acid (ABA) plays a
fundamental role in stress adaptation in plants and in integrating and fine-tuning stress-response signalling
networks [1,2] and triggers downstream expression of drought-response genes via the ABF transcription
factor [3]. The detailed signalling pathway involved is beginning to be unravelled in Arabidopsis [4] and some work on these regulatory pathways and gene networks in other species has been carried out [5,6]. In barley, curtailment of grain filling and hence yield during terminal drought stress is mediated by changes in ABA levels [7]. It will be important to understand how different stress-signalling pathways interact in barley because there is accumulating evidence for severe trade-off effects between, e.g., stress imposed by drought and biotrophic pathogens [8]. ClimBar will contribute to this understanding. Barley is emerging as a model for studying the genetics of stress adaptation; quantitative trait loci (QTL) and candidate genes for biotic and abiotic stress resistance have already been identified in barley [9,10], although their relevance to large germplasm sets and particular physiological features related to resilience, as studied in ClimBar will need to be established. An emerging and important question is the means by which stress response is communicated to the next generation. A resilient response to stresses induced by climate change implies that a plant will not only recover from the stress, but also that the next generation will not be compromised in its germination, growth, yield, or quality. Progeny of infected plants can display epigenetic memories of infections in the parents [11]. There are emerging lines of evidence that epigenetic DNA methylation and histone modifications such as those mediated by polycomb group of proteins are responsive to ABA and active in barley embryos [12,13]. Recent work in Arabidopsis has uncovered loci controlling epigenetic effects [14], a genetics of epigenetics; this suggest that the ClimBar study may uncover a parallel set of loci in barley, helping to provide breeding leads for resilience.

Climate Smart Agriculture requires both the conservation of genetic resources and their effective use to
develop regional varieties with sufficient resilience to deliver yield, quality and stability under increased and
different seasonal stresses and decreased inputs. ClimBar will identify critical genes and alleles in the barley
gene pool conferring resilience. It will use a structured diversity set of varieties, landraces, and CWR lines as
the key to unlocking and conserving genetic diversity in much larger collections. Specifically, the project will
produce: a set of agronomically important phenotypes linked to loci, chromosomal regions and alleles;
detailed physiological profiles for the function of the alleles under climate-change scenarios; high-precision
disease responses versus alleles and climate change; linkage between alleles, physiological response and
the epigenetic and regulatory states behind trans-generational resilience. GWAS will serve to link genotype to
phenotype and genotype to climate. Models for the relationship between loci and ecogeography will be used
as a prediction tool for future barley breeding goals. Data will be fed forward into ago-economic modelling for
policy decisions. These data will provide a platform for incorporating both in situ and ex situ allelic diversity
into breeding programs, increasing genetic richness of the cultivar set, and forming a basis for multi-varietal
cultivation. Adapted, resilient germplasm created using ClimBar data, tools and models will provide food-chain
security, economic stability and environmental sustainability.

The Triticeae cereals are a dominant component of European agriculture and barley, as a simple diploid, is a model for genomics-assisted molecular breeding. Making the assumption that the results obtained here will lead to advances in genetics/plant breeding and biotechnology (which we strongly believe), the immediate beneficiaries of the project will be commercial sector organisations that breed new varieties and the farmers that grow these new varieties on their farms and in their fields. It is widely appreciated that the conduit through which almost all genetic advances in crop production must pass to release their benefits to the broader community is the plant breeding / biotech sector. Translational activities from basic science to application are therefore crucial. The EU boasts one of the most efficient and successful commercial cereal breeding sectors in the world and it is important to recognise that the PIs in ClimBar maintain long lasting, strong and funded collaborations with all of the major barley breeders in Europe. They have proactively engaged this community and will continue to do so during the project. The PIs likewise have links to major food, feed, brewing, distilling and academic and applied sectors and a strong identity within the global community. Our proposal to largely utilise both germplasm and re-sequencing data from existing National and European Framework Program Grants (WHEALBI) is an important sign of the productive interactions that the participants have with the broader barley/wheat research community and highlights their desire to unify and enhance current state of the art research platforms and to avoid duplication. The work proposed here will enhance and broaden the impact of the funded WHEALBI project by focusing on phenotypes and molecular and environmental responses not covered in that project. We will extend our dialogue with the WHEALBI management team to discuss the integration of data in a common informatics hub. We will also interact with climatic and eco-economic modelling consortia and projects, e.g., MACSUR, AgMIP, and ISI-MIP. The PIs have the relevant profile, expertise, track record and motivation to ensure that this happens effectively.