CAMBIA’s Modular Approach

green gus

Transgenic plants expressing the GUSPlus in vivo reporter enzyme can be assayed with GUS substrates to give rise to a blue colour in the plant tissue

In a systems approach to get the engineered biosentinel concept working in a crop system to address real local constraints, we envision a biosentinel with at least five modular components:
  1. A suitable species and a universal transformation system:- Does the plant have to be in the food chain or the non-food chain? What are the consequences of either option?  Some of the desired characteristics for such a plant: a) highly relevant to the problem, b) easily transformable, c) can be rendered sterile, if need be, and d) from a regulatory perspective, preferably it contains the appropriate sensor or its homologue.  With the availability of CAMBIA’s TransBacter project and the help from the Lemelson Foundation grant, the project focused on this first module and on building new universal gene transfer machinery to enable transformation of various crops.
  2. An identified or engineered sensor with a promoter: – preferably regulatory elements or genes that are specifically induced or regulated in response to the constraint that needs addressing.  CAMBIA developed a technology landscape on regulatory elements and in this project, we continue updating the list of publicly available promoters but we welcome your input by E-mail.
  3. Engineered sensor with a marker or a detectable signal:- this step may be critical in its design since it will depend on the type of the sensor used, the location in plant where the response is needed, the type of reporter used, and its regulation mode.  Regulation of the time and duration of the response is important (inducible system for short (hours) or long (days) or constitutive for indefinetely).  This step will depend on the purpose of the application needed and the previous steps.
  4. A detection system for humans (an inventive device, or one of the five senses), ideally nondestructive, inexpensive or costless to use, reliable under field conditions and requires no instrumentation. Translation of the signal into something that can be observed, such as wilting, an odor, or a visible or infra-red color change mediated by a GUS gene product, an anthocyanin gene or similar genes, expressed in a part of the plant that is observable. (Ideally, the signal should be quantifiable, expressed in proportion to the level of the physiological parameter being detected. In the best mode, two signals could be used, which can be compared against each other for high accuracy.
  5. Field applicability (How to measure the response? How does it perform in the field? Does it meet the intended specifications? How to account for microenvironment variability?  How to establish confidence levels in the measurement of the response?) and what are the ways to act on or share the information?

An added value to the systems approach is that it can bring non-transgenic or post-transgenic modules to service. We envision an “Apollo Project” of biosentinel components that can be useful as part of a repertoire from which the appropriate modules can be chosen locally for empowering particular actions by farmers and breeders.  Such actions will more likely lead to adoption and further innovation of the technology as compared to the provision of a complete bioindicator prototype.

In this project, CAMBIA brings in more than 15 years of experience evaluating and thinking about Biosentinels, offers highly distinctive visual markers and  transactivation cassettes to help move this technology into a real working model.

Realizing that there may be even better visual markers and promoters out there, we hope this provides impetus for talented groups that may identify and/or provide such useful markers for the bioindicators project as a public good. Do you know of any that might be really useful for this purpose?

Most of the previous research has been done on Arabidopsis using Agrobacterium methods encumbered by a variety of patents that prevent practical use outside companies that have closely held licenses.

CAMBIA, via a BiOS license, is also offering the TransBacter technology to encourage participants to use the method to obviate these obstructive licensing practices for biosentinels for public good.

Modules developed by inovative individuals within this project may be patented, but the capability to use them for research and commercial purposes by all those interested to use and improve them for public good will be governed by a BiOS license .