Molecular Dissection of Proanthocyanidin and Anthocyanin Biosynthesis in White Clover (Trifolium repens)

摘要

Proanthocyanidins (PAs) form the basis for bloat-safety in a number of forage legumes. An attractive strategy for increasing the level of PAs in the foliage of forage legumes, including white clover (Trifolium repens) and alfalfa (Medicago sativd), involves metabolic reprogramming to divert intermediates from the pre-existing anthocyanin (ANT) pathway to PA biosynthesis. The ANT and PA pathways show remarkable similarities at the molecular and biochemical levels. However, modification of flavonoid biosynthesis to produce an agrono-mically desirable level of PA in foliage (2-4% of dry weight) is still a formidable task. To meet this challenge, a deeper understanding of the spatial patterns of ANT and PA accumulation in different tissues and cells ofwhite clover and changes associated with development and exposure of plants to stress is required. Improved knowledge of PA and ANT biosynthesis should enhance the ability to reprogram the flavonoid pathway to develop bloat-safe white clover plants withan elevated level of PA in the foliage.