R-GRAIN

Common rye (Secale cereale L.) is cultivated on over 700,000 hectares in Poland, making it the largest area dedicated to this crop in the European Union. As its environmental resistance vastly surpasses that of other cereal species, the growth of rye is an attractive, prospective answer to tackling the mounting demands of climate change. Naturally, this growing demand calls for an intensification of research, with the yielding properties of rye in the limelight. The traits we focused on throughout the R-GRAIN project, were the size and weight of grain. We initiated our work by screening the Secale cereale collection of the Polish Genebank. We studied 200 rye genotypes with thousand grain weight (TGW) ranging between 15 and 62 grams . Through extensive phenotypic characterisation, we identified six genotypes that exhibited extreme grain sizes, while maintaining typical characteristics of modern cultivars. These selected genotypes were then subjected to detailed transcriptomic analyses during the development of grain. Differential gene expression analyses conducted on grains harvested 7 days after pollination, revealed a significant, grain size correlated, change in the expression of genes implicated in cell proliferation. The genes with their expression patterns correlated with grain weight, were subjected to pathway and gene ontology enrichment analyses. Thus, identifying the potential physiological mechanisms leading to an increase in grain size. Both the structure and sequence of these genes were further analysed, allowing the identification of polymorphisms associated with rye grain size in materials from Polish rye breeding stocks and gene bank. This ongoing research into unravelling the mechanistic implications of these changes, will enable the development of molecular markers that can characterise traits with yield potential at early stages of plant selection.