Meiotic temperature resilience in wild barley

• Applicant: Dr. Steven Dreissig
• Subject Area: Plant Breeding and Plant Pathology
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 528289994

The successful development of gametes through meiosis is essential for grain yield. Meiosis is highly sensitive to temperature extremes and gamete development fails after short exposure to high temperatures.The central aim of this project is to identify alleles conferring an increased resilience of meiosis against high temperatures in order to secure yield stability under changing climate conditions. This is based on the hypothesis that alleles of genes mediating temperature resilience evolved through natural selection in the wild ancestors of contemporary crops. Meiosis is a specialized cell division fundamental to eukaryotic reproduction which gives rise to novel allelic combinations and ensures successful gamete development and fertilization. Previous work in mice, nematodes, Arabidopsis, wheat, and maize showed that multiple stages of meiosis are highly temperature sensitive, where short periods of extremely high temperatures lead to failures of the meiotic programme. Especially during meiotic prophase, increased temperature was shown to impair these processes, ultimately leading to unbalanced gametes and reduced fertility. So far, few studies investigated meiotic temperature resilience in diverse genotypes or crop wild relatives. We are planning to leverage a large wild barley nested-association-mapping population derived from a cross between one domesticated barley variety (“Barke”) and 25 wild barleys. This wild barley population was extensively characterized at the phenotypic and genomic level, with demonstrated phenotypic variation regarding yield, developmental traits, morphological traits, and biotic and abiotic stress tolerance. Furthermore, genomic information, such as high-density SNP data based on a 50K Illumina iSelect array and exome capture sequencing, as well as chromosome-level pan-genome assemblies, are available. To quantify temperature resilience of meiosis, we will measure the progressing of male meiosis and gamete development directly using cytogenetics methods and high-throughput imaging flow cytometry, and faithful completion of female meiosis will be inferred based on the ratio of pollen fertility to spikelet fertility. This project will focus on the following three objectives: (i) We will initially screen the 25 wild barley donors of our mapping population for phenotypic variation in meiotic temperature resilience, and select families with divergent phenotypes for further analysis. (ii) Selected families comprising a minimum of 200 lines will be used for genome-wide association scans to identify candidate genes. (iii) Finally, selected genes will be validated via fine-mapping in heterogeneous inbred families and subjected to in-depth characterization of meiosis at high temperatures. This approach will not only allow us to validate effects of candidate genes, but bears the potential to improve our understanding of genes, and allelic variants thereof, involved in meiosis and meiotic temperature resilience in plants.

• DFG Programme: Research Grants