Development and Applications of Transplastomic Plants; A Way Towards Eco-Friendly Agriculture

With distribution of genetic materials and advance molecular characteristics, the chloroplast is prokaryotic compartments within the eukaryotic plants that have turned into a crucial source for the genetic engineering and transplastomic plants are becoming more popular means of agricultural development with elevated crop yield. To address global agricultural problems, genetic modification of crop plants is a rapid and promising solution to adapt the environment-friendly and well-controlled farming system. The transplastomic plant with high accumulation of foreign proteins (up to 45-46% TSP) and stable transgene expression with gene containment can be a unique choice for the agricultural innovation of coming centuries. Although the transplastomic plants still facing encumber to ensure the full potential exploitation and expansion as an economical means, the removal of hardness and obstacles of this technology and commercialization can contribute for the sustainable development of future agriculture. In this book chapter, we intend to recapitulate the up to date development and achievement of transplastomic plant including gene transfer procedures in plastid genomes, regulable expression of plastid transgenes, plant trait improvement by foreign gene expression, biopharmaceuticals production, engineering of metabolic pathways in plant, study of transformation mediated RNA editing technologies, bio-safety issues and public concerns on transplastomic plants and overall beneficial aspects. We believe that the utilization of transplastomic plants will ensure an eco-friendly approach in agriculture with minimized hazards and public concerns. © Springer Nature Switzerland AG 2020

Inducible gene expression from the plastid genome by a synthetic riboswitch

Riboswitches are natural RNA sensors that regulate gene expression in response to ligand binding. Riboswitches have been identified in prokaryotes and eukaryotes but are unknown in organelles (mitochondria and plastids). Here we have tested the possibility to engineer riboswitches for plastids (chloroplasts), a genetic system that largely relies on translational control of gene expression. To this end, we have used bacterial riboswitches and modified them in silico to meet the requirements of translational regulation in plastids. These engineered switches were then tested for functionality in vivo by stable transformation of the tobacco chloroplast genome. We report the identification of a synthetic riboswitch that functions as an efficient translational regulator of gene expression in plastids in response to its exogenously applied ligand theophylline. This riboswitch provides a novel tool for plastid genome engineering that facilitates the tightly regulated inducible expression of chloroplast genes and transgenes and thus has wide applications in functional genomics and biotechnology

RiboTALE: A modular, inducible system for accurate gene expression control

A limiting factor in synthetic gene circuit design is the number of independent control elements that can be combined together in a single system. Here, we present RiboTALEs, a new class of inducible repressors that combine the specificity of TALEs with the ability of riboswitches to recognize exogenous signals and differentially control protein abundance. We demonstrate the capacity of RiboTALEs, constructed through different combinations of TALE proteins and riboswitches, to rapidly and reproducibly control the expression of downstream targets with a dynamic range of 243.7 ± 17.6-fold, which is adequate for many biotechnological applications