Regulatory mechanisms of carotenoid biosynthesis in potato tubers

Isoprenoid biosynthetic pathways provide a wide-range of metabolites essential for plant development and storage organ food quality. Amongst them are carotenoids, photosynthetic pigments and important micronutrients with provitamin A activity. Globally, it was estimated that 140–250 million children under five years of age are affected by vitamin A deficiency, so understanding the regulation of isoprenoid metabolic networks is fundamental in producing foods with enhanced nutrient content. Many isoprenoids are synthesized in the plastid, however in potato tubers there are gaps in our knowledge about how this biosynthesis is regulated. Previous transgenic work, whilst providing proof of principle that gene expression changes can bring about improvements (Shewmaker et al. 1999; Ducreux et al. 2005), have not helped us understand the different tiers of regulation that can be addressed to make further improvements in isoprenoid levels. Results RFP and GFP tagged fusions of Gateway binary vectors were created using the backbone of pK7FWG2 and pK7RWG2 (VIB, UGENT) together with the coding sequences of phytoene synthase PSY 2 and beta carotene hydroxylase CrtRB2 from potato (see Figure 2). These constructs were then used for- transient expression in Nicotiana benthamiana, Solanum tuberosum cv Desiree and Solanum phureja c