The vernalisation pathway is a key component of fowering time control in plants from temperate regions but is not well understood in the legume family. Here we examined vernalisation control in the temperate grain legume species, narrow-leafed lupin (Lupinus angustifolius L.), and discovered a candidate gene for an ethylene imine mutation (ef). The ef mutation changes phenology from late to mid-season fowering and additionally causes transformation from obligate to facultative vernalisation requirement. The ef locus was mapped to pseudochromosome NLL-10 in a recombinant inbred line (RIL) mapping population developed by accelerated single seed descent. Candidate genes were identifed in the reference genome, and a diverse panel of narrow-leafed lupins was screened to validate mutations specifc to accessions with ef. A non-synonymous SNP mutation within an S-adenosyl-L-methionine-dependent methyltransferase protein domain of a Trimethylguanosine Synthase1-like (TGS1) orthologue was identifed as the candidate mutation giving rise to ef. This mutation caused substitution of an amino acid within an established motif at a position that is otherwise highly conserved in several plant families and was perfectly correlated with the ef phenotype in F2 and F6 genetic population and a panel of diverse accessions, including the original ef mutant. Expression of the TGS1 homologue did not difer between wild-type and ef genotypes, supporting altered functional activity of the gene product. This is the frst time a TGS1 orthologue has been associated with vernalisation response and fowering time control in any plant species.
Taylor, C. M., Garg, G., Berger, J. D., Ribalta, F. M., Croser, J. S., Singh, K. B., Cowling, W. A., Kamphuis, L. G. and Nelson, M. N. (2021)