Production of species-specific anthocyanins through an inducible system in plant hairy roots.

Anthocyanins are widely distributed pigments in flowering plants with red, purple or blue colours. Their properties in promoting heath make anthocyanins perfect natural colourants for food additives. However, anthocyanins with strong colour and stability at neutral pH, suitable as food colourants are relatively rare in nature. Acylation increases anthocyanin stability and confers bluer colour. In this study, we isolated two anthocyanin regulators SbMyb75 and SbDel from S. baicalensis, and showed that constitutive expression of the two TFs led to accumulation of anthocyanins at high levels in black carrot hairy roots. However, these hairy roots had severe growth problems. We then developed a ß-estradiol inducible system using XVE and a Lex-35S promoter, to initiate expression of the anthocyanin regulators and induced this system in hairy roots of black carrot, tobacco and morning glory. Anthocyanins with various decorations were produced in these hairy roots without any accompanying side-effects on growth. We further produced highly acylated anthocyanins with blue colour in a 5 L liquid culture in a bioreactor of hairy roots from morning glory. We provide here a strategy to produce highly decorated anthocyanins without the need for additional engineering of any of the genes encoding decorating enzymes. This strategy could be transferred to other species, with considerable potential for natural colourant production for the food industries.

Holding the product of visual working memory integration: The role of attention.

The involuntary integration of discrete fragments into meaningful units (e.g., Gestalt) within visual working memory (VWM) is a crucial process in mind. However, the mechanisms governing the maintenance of these integrated products within VWM have remained largely unexplored. The current study sought to address this gap by investigating whether maintaining such VWM integration products places a greater demand on attention resources compared to discrete representations. We hypothesized that maintenance may be costless or require additional attention, which may be domain-specific or domain-general. To examine these hypotheses, we tested whether the emerged Gestalts by VWM integration can be abolished by an attention consumption task. Participants were required to memorize a sequence of oriented disks with or without Gestalt cues, alongside a secondary task during maintenance, consuming a specific type of attention. We found that a task consuming spatial attention impaired the VWM Gestalts of bar contours (Experiments 1 and 3), but not the Gestalts of square contours (Experiment 2). Moreover, a task consuming domain-general attention did not affect the VWM Gestalts of bar contours (Experiment 4). These findings provide evidence suggesting that maintaining VWM integration products requires more attention than discrete representations and that the type of attention required is domain-specific.