Improving transient protein expression in agroinfiltrated Nicotiana benthamiana.

Agroinfiltration of Nicotiana benthamiana is routinely used in plant science and molecular pharming to transiently express proteins of interest. Here, we discuss four phenomena that should be avoided to improve transient expression. Immune responses can be avoided by depleting immune receptors and employing pathogen-derived effectors; transcript degradation by using silencing inhibitors or RNA interference machinery mutants; endoplasmic reticulum stress by co-expressing chaperones; and protein degradation can be avoided with subcellular targeting, protease mutants and co-expressing protease inhibitors. We summarise the reported increased yields for various recombinant proteins achieved with these approaches and highlight remaining challenges to further improve the efficiency of this versatile protein expression platform.

An Agrobacterium rhizogenes mediated hairy root transformation protocol for fenugreek.

•This work describes a protocol for hairy root transformation of the medicinal crop legume fenugreek (Trigonella foenum-graecum L.). Hairy root plant transformation mediated by Agrobacterium rhizogenes is an established method for the rapid genetic transformation of various dicotyledonous plants. We have adapted a hairy root transformation protocol from the model legume Medicago truncatula for use in this metabolically rich non-model crop legume. Considering the great variety and abundance of phytochemicals in fenugreek and its established use in traditional medicine, we aim for this method to become a resource for metabolic pathway identification and for production of valuable specialised metabolites via metabolic engineering approaches.•Development rapid transformation (2.5-3 weeks) of fenugreek roots via A. rhizogenes.•Marker gene cassette with suitable promoter for visual detection of transformed fenugreek roots.

A hairy-root transformation protocol for Trigonella foenum-graecum L. as a tool for metabolic engineering and specialised metabolite pathway elucidation.

The development of genetic transformation methods is critical for enabling the thorough characterization of an organism and is a key step in exploiting any species as a platform for synthetic biology and metabolic engineering approaches. In this work we describe the development of an Agrobacterium rhizogenes-mediated hairy root transformation protocol for the crop and medicinal legume fenugreek (Trigonella foenum-graecum). Fenugreek has a rich and diverse content in bioactive specialised metabolites, notably diosgenin, which is a common precursor for synthetic human hormone production. This makes fenugreek a prime target for identification and engineering of specific biosynthetic pathways for the production of triterpene and steroidal saponins, phenolics, and galactomanans. Through this transformation protocol, we identified a suitable promoter for robust transgene expression in fenugreek. Finally, we establish the proof of principle for the utility of the fenugreek system for metabolic engineering programs, by heterologous expression of known triterpene saponin biosynthesis regulators from the related legume Medicago truncatula in fenugreek hairy roots.