Biomimicry as a Tool for Studying Plant - Environment Interaction

Using biomimicry in a new way – instead of imitating nature to better human life, we are imitating nature to better understand nature
May 6, 2019

 

Biomimicry is an approach to innovation that seeks sustainable solutions to human challenges by emulating nature’s time-tested patterns and strategies. Biomimicry uses tools in the fields of materials science and engineering and looks at nature for inspiration. The best-known example in biomimicry concerns the lotus leaf.

The lotus flower is an aquatic plant. The leaves of the plant are known for their super hydrophobicity – “the lotus effect”. This super hydrophobicity is a result of the microstructure on the surface of the leaf rather than the surface chemistry. Scientists and engineers have used the lotus leaf, over the years, as an inspiration to generate super hydrophobic surfaces, mostly for self-cleaning purposes.

Lotus flower                                       Lotus leaf                                                       Lotus leaf surface microstructure **

** adapted from G. Carbone and L. Mangialardi, Eur. Phys. J. 16(1):67-76 (2005)  

                                                                             
Our research is taking the tools of biomimicry – imitating natural structures –and uses them to learn more about nature rather than as synthetic technological tools. We view the surface of the plant as the entry gate to the plant. Any interaction that the plant has with the environment begins with the surface.

 

Looking at an interaction between a plant and a living organism such as bacteria, fungus or insect, the initiation of the reaction occurs on the surface. During this interaction many signals are being transmitted between the plant and the other organism – molecules and chemicals are secreted and absorbed from both parties. While these chemical and molecular signals are widely studied in these interactions, one is usually ignored – the physical signal of the microtopography of the surface.

Studying this physical signal using the natural system can be quite challenging as the biological system is very noisy with all the additional molecular and chemical signals. Hence, it is essential to find a different method to study the effect of structure on plant-environment interactions. We are using biomimetics to do exactly that. We are building synthetic surfaces that replicate the structure to less than a micrometer precision. Our surfaces are inert and are currently made from the biocompatible, transparent, inexpensive and commercially available polymer polydimethylsiloxane (PDMS). We prepare the surfaces using a simple method of double molding called soft lithography.

 

Soft Lithography

Soft  

 

   

Natural (left) and synthetic (right) leaf surface structure. Middle shows the first mold – the negative of the structure


One of our model systems is the botrytis-tomato system. Botrytis cenerea is a pathogenic fungus that has many hosts, tomato being one of them, and is the agent of the grey mold disease. The fungus distributes as spores using wind, lands on the surface of the plant– often the leaves, and given the right conditions germinates and penetrates the plant. The disease causes lesions on the plant and fruit causing crop loss and financial damage. The size of the fungus spores is around 10 micrometer – on par with the leaf surface micro topographical features.

 

   

Grey mold disease in tomatoes and botrytis spores on the leaf surface 

 

Using this model system, we are studying the influence of the surface structure on the fungus

development and possibly pathogenic ability.

Growing spores on both flat and structured PDMS surface we learned that the spores germination is quicker and more efficient on a flat surface – suggesting the plant uses the surface structure as an initial, primitive defense mechanism. Additionally, we learned that the spread of the fungus colony on agar plates is highly dependent on the surface structure. The colony will spread in a circular manner on a flat surface but will spread along the vascular system of the leaf on a leaf structured surface. This phenomenon was observed in the natural system with other fungi and was attributed to the high concentration of sugar and nutrients in the vasculature system. We observed this phenomenon on a synthetic surface where the chemistry and nutrient availability was identical in all directions. Our system proves that the signal obtained by the fungus is structural rather than chemical showing adaptation of the fungus to the plant system and specifically the surface structure.

 


 

 

Spread of botrytis cenerea on agar plates. Colony spreads in a circle in unpatterned plates (lower raw) and along the vascular system of the leaf in the leaf structure patterned plate (upper row)


In summary, we are developing a new system which aims at separating the chemical/molecular signal in plant-environment interaction from the physical/topographical signal. Our system is expected to shed new light on plant-pathogen, plant-microbiome, plant-air, plant-soil interactions, emphasizing the role of the surface as the immediate barrier and the surface structure as an additional, previously overlooked, signal. We are using biomimicry in a new way – instead of imitating nature to better human life, we are imitating nature to better understand nature.

*Agricultural Research Organization (Volcani Center) Institute of Plant Sciences
Department of Vegetables and Field Crops

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