Spatio-temporal profile of the anthocyanidin reductase gene expression in white clover flowers

Proanthocyanidins (PAs) are polymers of flavan 3-ol subunits that are naturally produced by some plants and ameliorate pasture bloat in livestock. Genes encoding proteins involved in the biosynthesis, intracellular transport and compartmentalisation of PAs and their precursors are tightly regulated by transcription factors. In this study, the expression pattern of an anthocyanidin reductase (ANR) gene was shown to correlate with the accumulation pattern of PAs and/or their monomers in white clover (Trifolium repens L.). The sub-cellular localisation patterns of an ANR-GFP fusion protein and proanthocyanidins and/or monomers are consistent with biosynthesis of flavan 3-ols in the cytoplasm prior to PA accumulation in the vacuole of cells in flowers. Characterisation of the white clover ANR gene provides a valuable resource for further work aiming to improve bloat safety in white clover by elevating PA levels in leaves.