BOOM V

Bacteria-Originated
Outer Membrane Vesicles

...as a novel plant protection strategy

“Global agriculture is facing big challenges”

Prof. Beat Keller, expert of phytopathology at the University of Zurich, tells us in our interview with him [1]. There are three main aspects to this:

The global population is ever increasing, and this in turn also increases the demand for more food. In 2019 8.8% of the population were insufficiently fed, in 2021 that number has increased to about 10%. This proves that with our current approach, we are failing to provide a sufficient amount of food in a reliable manner. We need to rethink our current approach, and come up with new solutions [2].

As earth has a limited size, the amount of arable land per capita is decreasing. Currently, we are using half of the world’s habitable land for agriculture, and are still not able to produce enough food. This problem is further exacerbated because 77% of that farming land is used to produce feed for livestock. Therefore, new solutions need to increase our efficiency in food production while maintaining or even decreasing the required amount of land [3].

Our current agricultural practices are not sustainable. For example, current agricultural practices are leading to a decreasing soil quality, which in turn decreases the soil’s potential to produce food. This problem is mainly caused by monocultures and the use of synthetic pesticides. These remain in the soil for years after being used, which negatively influences the microbiome of the soil. We need new compounds which have reduced off-target effects and do not negatively impact the ecosystem that it is applied to [4].

Our University is leading in the field of Plant Biology. This is why we decided to develop a novel plant protection strategy to pave the way towards a more sustainable agriculture.

Pesticides were a hot topic in Switzerland this summer:

In June, we voted on two popular initiatives that aimed to reduce the use of synthetic pesticides.

For a Switzerland without synthetic pesticides

For clean drinking water and healthy nourishment - No subventions for the use of pesticides and prophylactic treatment with antibiotics

The main concerns addressed by these initiatives with regard to the use of pesticides are our responsibilities towards the environment, protection of biodiversity, and adverse health effects on humans [5]. Even though both of the initiatives were rejected, the discussions have made it clear that new solutions are necessary.

Luckily, we did not have to look far since nature had already designed a complex defense mechanism in plants that we could make use of: Pattern triggered immunity. PTI can be thought of as the first line of defense in plants and the effects of its activation are diverse [6].

PTI can be triggered by so-called pathogen associated molecular patterns (PAMPs). They are non-self microbial molecules that are often highly conserved [6]. Simply put, when the plant senses a molecule that it doesn’t have, it thinks that there is a pathogen and will start to protect itself.

Would it be possible for us to transport PAMPs on something to trigger PTI so that we can help the plant?
This is when we came across outer membrane vesicles (OMVs). They are buddings of the outer membrane of gram-negative bacteria that are produced naturally, and are intrinsically capable of inducing PTI [7].

So this is BOOM V:

Engineered bacteria-originated outer membrane vesicles as a novel plant protection strategy.

[1] Research, Regulations and Resistance: An Interview with Prof. Beat Keller by iGEM UZH 2021, 12. October 2021
[2] WHO news, 16. October 2021
[3] Our World in Data, 16. October 2021
[4] Beretta, Andres et al. "Soil quality decrease over 13 years of agricultural production." Nutrient Cycling in Agroecosystems vol. 114 45-55. May 2019, doi:10.1007/s10705-019-09990-3
[5] Post-vote Analysis, 12. October 2021
[6] Hou, Shuguo et al. “Damage-Associated Molecular Pattern-Triggered Immunity in Plants.” Frontiers in plant science vol. 10 646. 22 May. 2019, doi:10.3389/fpls.2019.00646
[7] Bahar, Ofir et al. “Bacterial Outer Membrane Vesicles Induce Plant Immune Responses.” Molecular plant-microbe interactions: MPMI vol. 29,5 (2016): 374-84. doi:10.1094/MPMI-12-15-0270-R