Proanthocyanidins (PAs) are oligomeric flavonoids and one group of end products of the phenylpropanoid pathway. PAs have been reported to be beneficial for human and animal health and are particularly important in pastoral agricultural systems for improved animal production and reduced greenhouse gas emissions. However, the main forage legumes grown in these systems, such as Trifolium repens and Medicago sativa, do not contain any substantial amounts of PAs in leaves. We have identified from the foliar PA-accumulating legume Trifolium arvense an R2R3-MYB transcription factor, TaMYB14, and provide evidence that this transcription factor is involved in the regulation of PA biosynthesis in legumes. TaMYB14 expression is necessary and sufficient to up-regulate late steps of the phenylpropanoid pathway and to induce PA biosynthesis. RNA interference silencing of TaMYB14 resulted in almost complete cessation of PA biosynthesis in T. arvense, whereas Nicotiana tabacum, M. sativa, and T. repens plants constitutively expressing TaMYB14 synthesized and accumulated PAs in leaves up to 1.8% dry matter. Targeted liquid chromatography-multistage tandem mass spectrometry analysis identified foliar PAs up to degree of polymerization 6 in leaf extracts. Hence, genetically modified M. sativa and T. repens plants expressing TaMYB14 provide a viable option for improving animal health and mitigating the negative environmental impacts of pastoral animal production systems.

The expression of anthocyanin biosynthesis genes during flower colour development in Anthurium andraeanum (anthurium) was studied. A cDNA library was constructed from mRNA from the anthurium spathe, and full‐length cDNA clones identified for the flavonoid biosynthetic enzymes chalcone synthase (CHS), flavanone 3‐hydroxylase (F3H), dihydroflavonol 4‐reductase (DFR) and anthocyanidin synthase (ANS). These were used to measure transcript levels in the spathe during flower development, in cultivars with different flower colours, over the diurnal cycle, and in the spadix. CHS, F3H and ANS were expressed at all stages of spathe and spadix development. However, DFR transcript levels varied significantly between stages, and DFR may represent a key point of regulation. A diurnal rhythm of DFR transcript abundance in the spathe was also observed, with transcript levels high at dawn and dusk and low at noon. Control of anthocyanin biosynthesis in anthurium spathe differs from that described for flowers of other species, with DFR a key regulatory point and a complex mix of developmental and environmental control signals.

Cymbidium hybrid 'Jung Frau dos Pueblos' (JDP) is a commercial white flowered orchid cultivar. In this study we investigated whether anthocyanin pigment production could be restored to JDP petals by introducing known anthocyanin-regulating transcription factors through biolistic transformation. Simultaneous transformation of white JDP petals with the maize anthocyanin regulators Leaf color and Colorless1 restored anthocyanin biosynthesis, producing a characteristic biolistic blast pattern of scarlet anthocyanin-producing cells. The effectiveness of different MYB/bHLH combinations to induce anthocyanin pigmentation in JDP petals was assessed, and we demonstrate that the previously uncharacterized R2R3 MYB transcription factor AaMYB1 from Anthurium andraeanum is capable of activating anthocyanin production in Cymbidium petals. The clear distinction between the effectiveness of MYB factors from monocot versus dicot species for inducing anthocyanin pigmentation suggests a specificity of transcription factors between monocots and dicots and that this may be determined by the MYB factor.