Engineering metabolic pathways in plants by multigene transformation

Abstract

Metabolic engineering in plants can be used to increase the abundance of specific valuable metabolites, but single-point interventions generally do not improve the yields of target metabolites unless that product is immediately downstream of the intervention point and there is a plentiful supply of precursors. In many cases, an intervention is necessary at an early bottleneck, sometimes the first committed step in the pathway, but is often only successful in shifting the bottleneck downstream, sometimes also causing the accumulation of an undesirable metabolic intermediate. Occasionally it has been possible to induce multiple genes in a pathway by controlling the expression of a key regulator, such as a transcription factor, but this strategy is only possible if such master regulators exist and can be identified. A more robust approach is the simultaneous expression of multiple genes in the pathway, preferably representing every critical enzymatic step, therefore removing all bottlenecks and ensuring completely unrestricted metabolic flux. This approach requires the transfer of multiple enzyme-encoding genes to the recipient plant, which is achieved most efficiently if all genes are transferred at the same time. Here we review the state of the art in multigene transformation as applied to metabolic engineering in plants, highlighting some of the most significant recent advances in the field.

Synthetic biology for production of natural and new‐to‐nature terpenoids in photosynthetic organisms

“…Traditionally, multigene pathways have been engineered in plants by sequential transformation of transgenic lines with additional genes or by crossing of homozygous transgenic lines. Both techniques are slow and labour‐intensive and may lead to segregation of the transgenes in later generations (Naqvi et al ., ; Pollier et al ., ; Zorrilla‐López et al ., ; Farré et al ., ).…”

Fruit-specific expression of crtB, HpBHY, CrBKT and SlLCYB triggers hyper-production of carotenoids in tomato fruit

“…Thus, to effectively improve the production of a metabolite, it is sometimes necessary to express more than two key enzymes. Multigene transformation is still a challenge of plant genetic engineering, which usually depends on a large construct or co-transformation of multiple constructs [24,25]. 2A peptide sequence of the foot-andmouth disease virus could govern self-processing of polyproteins, which was successfully used in multigene co-transformation [26].…”

Recent developments in therapeutic protein expression technologies in plants

“…However, plant expression systems excel in the production of plant-derived edible vaccines (Goeddel et al 1979;Mishra et al 2008;Yang and Yang 2010) and have tremendous growth potential as the basis of the modern discipline, providing immediate cures for infectious diseases. Simultaneous expression of multigenes reviewed by (Zorrilla-Lopez et al 2013) into plants can alter complex metabolic pathways that can be used to produce compounds of pharmaceutics.…”