18-BTT:Harnessing the power of cellular memory to enhance the breeding potential of crops

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The creation of strains of commercially important crops such as maize, squash, and cotton has resulted in vastly increased crop yields as well as resistance to pesticides and herbicides. While these strains are ideal for sustaining a rapidly expanding global population, the prioritization of homogeneity and productivity over reliable and diversified food production has resulted in a severe loss of genetic variation. Traditional approaches for reintroducing genetic variation into agriculturally important strains involve crossbreeding with wild relatives, which possess more genetic diversity than crop strains. However, backcrossing with wild relatives often results in the introgression of additional traits which lower yield.Alternatively, it may be possible to harness hidden genetic diversity already present in crop genomes which is normally transcriptionally silenced by repressive modifications such as DNA methylation. Removing DNA methylation at a genome-wide scale results in the heritable activation of loci normally silenced, leading to altered phenotypes from novel gene expression patterns. The creation of demethylated lines in model plant species has resulted in increased phenotypic diversity indicating that new, untapped source of variation that can be unlocked without genetic modification. Therefore, the creation of demethylated lines in species such as maize would serve to facilitate crop improvement by unlocking cryptic variation, promoting tolerance to changes in growth zones and the emergence of virulent pathogens. In this proposal we aim to create demethylated maize lines by taking advantage of our recent discovery that demethylation is induced during regeneration. There are two major goals of this proposal. The first, is to test the efficacy of induced demethylation and activation of silenced genes in maize as a result of direct plant regeneration from different tissues through somatic embryogenesis. The second goal, is to explore if coupling stress treatments with regeneration from somatic embryos could leads to epigenetic imprints that could enhance stress responses. We will combine our expertise of direct regeneration and epigenomics to assess the feasibility of this novel approach and to engineer plant genomes independent of genetic changes. The ability to successfully implement this method in maize will rapidly advance the ability to create desirable phenotypes and will advance plant biotechnology.