Date of this Version
Plant Biotechnology Journal
The impact of metabolic engineering on nontarget pathways and outcomes of metabolic engineering from different genomes are poorly understood questions. Therefore, squalene biosynthesis genes FARNESYL DIPHOSPHATE SYNTHASE (FPS) and SQUALENE SYNTHASE (SQS) were engineered via the Nicotiana tabacum chloroplast (C), nuclear (N) or both (CN) genomes to promote squalene biosynthesis. SQS levels were ~4300‐fold higher in C and CN lines than in N, but all accumulated ~150‐fold higher squalene due to substrate or storage limitations. Abnormal leaf and flower phenotypes, including lower pollen production and reduced fertility, were observed regardless of the compartment or level of transgene expression. Substantial changes in metabolomes of all lines were observed: levels of 65–120 unrelated metabolites, including the toxic alkaloid nicotine, changed by as much as 32‐fold. Profound effects of transgenesis on nontarget gene expression included changes in the abundance of 19 076 transcripts by up to 2000‐fold in CN; 7784 transcripts by up to 1400‐fold in N; and 5224 transcripts by as much as 2200‐fold in C. Transporter‐related transcripts were induced, and cell cycle‐associated transcripts were disproportionally repressed in all three lines. Transcriptome changes were validated by qRT‐PCR. The mechanism underlying these large changes likely involves metabolite‐mediated anterograde and/or retrograde signalling irrespective of the level of transgene expression or end product, due to imbalance of metabolic pools, offering new insight into both anticipated and unanticipated consequences of metabolic engineering.
This is the peer reviewed version of the following article: Pasoreck, E. K., Su, J., Silverman, I. M., Gosai, S. J., Gregory, B. D., Yuan, J. S., & Daniell, H. (2016). Terpene metabolic engineering via nuclear or chloroplast genomes profoundly and globally impacts off‐target pathways through metabolite signalling. Plant Biotechnology Journal, 14(9), 1862–1875. http://doi.org/10.1111/pbi.12548, which has been published in final form at http://doi.org/10.1111/pbi.12548. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving http://olabout.wiley.com/WileyCDA/Section/id-820227.html#terms.
Secondary metabolism, retrograde/anterograde signalling, transgenic/transplastomic plants, squalene
Pasoreck, E. K., Su, J., Silverman, I. M., Gosai, S. J., & Gregory, B. D. (2016). Terpene Metabolic Engineering Via Nuclear or Chloroplast Genomes Profoundly and Globally Impacts Off‐Target Pathways Through Metabolite Signalling. Plant Biotechnology Journal, 14 (9), 1862-1875. http://dx.doi.org/10.1111/pbi.12548
Date Posted: 01 March 2022
This document has been peer reviewed.