The target genes for Solanaceae secondary metabolism engineering: evolution and genome organization

Abstract

Metabolic engineering of plant secondary metabolism provides a way to obtain plants with elevated level of valuable molecular compounds. Alternatively, metabolic engineering can be used for reduction of toxic substances accumulation in plant tissues. This approach allows one to expand the application of toxic plants in agriculture and biotechnology. The crops of Solanaceae family provide an example of toxic plants of high economic value. Solanaceae family includes edible crops such as potato, tomato and eggplants, medicinal plants like Withania somnifera L. and major non-food crop Nicotiana tabacum L. The secondary metabolism of Solanaceae family is widely diverse and includes the biosynthesis and accumulation of number of toxic compounds, such as nicotine and other alkaloids in tobacco, steroidal glycoalcaloids in potato and withanolides in winter cherry W. somnifera. The secondary metabolic pathways of Solanaceae family have evolved from primary metabolism via duplication of the enzyme coding genes and diversification of genes functions. Local, segment and the whole genome duplications and subsequent formation of metabolic genes clusters are the main processes in secondary metabolic pathways formation. Recent whole genome sequence data from number of Sonanaceae species allows one to reconstruct the putative mechanism of primary and secondary metabolism genetic control and evolution. Genomic data together with novel guided endonuclease based genome modification tools provide an opportunity for introduction of precise changes into secondary metabolism. Suppression of nicotine accumulation in tobacco is promising approach for developing of novel plant systems for molecular farming. Toxicity of wild potato relatives impedes their usage in potato breeding. Tobacco and wild potato toxicity reduction can be achieved by different genome modification approaches: knock-out of the key enzyme genes of alkaloids synthesis, the large deletion of the whole cluster of the secondary metabolic genes or the precise editing of key transcription factors in secondary metabolism regulation pathways.

Keywords

• nicotiana tabacum
• potato
• tobacco
• genome engineering
• crispr/cas
• nicotine
• steroidal glycoalkaloids
• game genes