THE CHASSIS

Marchantia polymorpha represents the perfect choice in the endeavour of popularising synthetic biology and making it accessible to a larger audience. There are several reasons for this:

1. Marchantia polymorpha is a plant.
   Since plants play a role in every culture, people are comfortable around them – unlike bacteria. We realised that if we wanted to push forward the idea of a biosensor accessible to everyone it would have to be intrinsically user-friendly. What better than a small, low-maintenance, thalloid plant with tiny palm tree-like structures?
   
2. It has a small haploid genome which can be easily manipulated.
   Marchantia's genome size is only 280 Mb, which is little compared to other plants commonly used in biology. A haploid genome allows the user to disregard factors such as gene dominance relationships while genetically modifying the plant. With upcoming advances in mapping the genome, marchantia represents an ideal candidate for an open-source platform.
   
3. Marchantia is dioecious and has a short life cycle.
   Being dioecious, marchantia exists as either male or female plants, which are easily distinguishable at adult stages through the shape of their gametophyte. This in turn simplifies the crossing of two plants to an inexperienced user. Compared to the majority of other plants, the Marchantia polymorpha life cycle is short. It takes less than 3 months for a marchantia plant to grow from a spore into an adult plant capable of reproduction. It is no match for E. coli but surely beats other plants used in synthetic biology.
   
4. A single plant can produce hundreds of thousands of spores.
   The spores are very hardy, allowing them to be kept for over a year in a dry container. In addition, the hardiness allows for spores to be easily shipped without worrying about handling and temperature swings. Upon adding water to the spores, germination begins and the tiny plant begins to develop. The sheer number of spores produced by a single plant ensures*the presence of the desired offspring in the progeny.
   
5. Marchantia biosensors are renewable.
   The plants are easy to vegetatively propagate – either by grafting or via gemmae, tiny clones of the plants sporadically generated in gemma cups on the plant's surface. This ensures that once a useful biosensor is generated it can be easily distributed to your friends and family.
   

ASSEMBLING THE MODULES

Assembling a mӧsbi biosensor is arguably the simplest stage in creating bespoke biosensors. We have taken advantage of an innate ability of Marchantia polymorpha which allows us to generate new mӧsbis – good old fashioned crossing. By crossing plant lines with different single modules or module pairs (i.e. input-processor) – the so called seed lines - a proportion of the progeny will inevitably carry both parents' modules – in this way forming a partially or fully-assembled mӧsbi biosensor.
The crossing itself is an easy task which can be performed by anyone – even a child. One needs only to take a brush, dip it into water, and brush first the antheridium of a male plant, then the archegonium of a female, from pre-selected seed lines. This can be repeated several times and between different lines, giving rise to multiple mӧsbi variations from relatively few seed lines.
Selecting the recombinant progeny is done using pre-supplied (or independently created) antibiotic resistance plates for now. All mӧsbi modules are to be designed possessing specific antibiotic resistance genes in each module, or once more have been identified, different auxotrophic mutations. After the cross is completed and progeny spores are produced, these are either germinated on the three-antibiotic plates, or in the future auxotrophic system, a regular nutrient plate which will select for only those plants with complementary mutations. Only mӧsbis with 2 (in case of a 2-step cross) or all 3 modules will be able to grow on a given plate. In this way only the mӧsbi biosensors of interest are selected.
The assembly time varies depending if a 1 or 2-step assembly process is chosen by the user. A 1-step assembly process, starting with growing the seed lines from spores and finishing with the assembled mӧsbi biosensors growing on a selective plate will likely take approximately 2 months. Assembling a mӧsbi biosensor is certainly not an overnight task, however its simplicity and low equipment and knowledge requirements make it an interesting product for a new audience.