First contact 25.06
Skype conference 23.07
We approached apl. Prof. Dr. Ulrich Schaffrath from the Department of Plant Physiology at RWTH Aachen University to gather further information about pathogenic fungi and their impact on different aspects of society. Besides that, we hoped for an evaluation of our project and some advice for the optimization of our early concepts. We discussed our project and some questions during a Skype conference.
The working group of Prof. Schaffrath is doing research on pathogenic fungi that damage crops like cereals, for example wheat, barley and rice. Asian Soybean Rust is of especially high interest because it has the largest economic impact. A part of his research group is also working on the transformation of fungi. Prof. Schaffrath pointed out, that fungicide resistance has been an underrated problem for quite some time now. Meanwhile, resistances have become an even bigger problem and new strategies to fight them are urgently searched for. For example, the plant pathogen stripe rust diminishes the area of chlorophyll of the plant and thereby reduces its yield. Because they need lower temperatures, they only spread around the UK but meanwhile a new strain emerged that also thrives under the warmer climate in countries like Germany. Furthermore, the wheat stem rust strain Ug99 had overcome all resistances implemented into plants that have been used against it and poses a threat to whole harvests in all affected areas. A new counter strategy for the fight against pathogenic fungi, is the usage of a mixture between different reagents and coordinated usage of different fungicides at different times. Research has shown, that only a single nucleotide mutation is required to potentially gain resistance in pathogens against a fungicide. Because of this, resistances can emerge after one or two years of fungicide usage. Because only one base pair has to change to overcome such a pesticide, pathogens like wheat blast cannot be treated effectively with fungicides, which has led to huge problems in Brazil and other parts of the world. These pathogens make the necessity of new approaches even more urgent. Regarding the realisation of our system, Prof. Schaffrath described the legal situation in Germany and the EU as the biggest barrier. For the induced uptake via endocytosis he indicated that finding the right surface ligands will be one of the hardest tasks to accomplish, since many pathogens are not well researched. Moreover, many pathogenic fungi are quite hard to study in the lab. The wheat stem rust (Puccinia graminis f.sp tritici) for example is an obligatory biotrophic organism which cannot be grown in a petri dish. After we focussed on P. graminis at the beginning of our project, we shifted our attention on other pathogens after our discussion with Prof. Schaffrath.
While achieving specificity through the surface ligands, can be difficult to achieve for some species, accomplishing specificity through the Cas 13a is more likely to be successful, since many fungal genomes are characterised quite well. We decided to make this part the most important one to assure the specificity of our Troygenics, additional to the other measures like the specific ligands. Another approach we discussed, was the idea to use mycoviruses as alternatives to our Troygenics. Prof. Schaffrath mentioned to not be an expert in this field, but we still managed to evaluate this topic. Since mycoviruses are not transmitted easily between fungi but rather through the fusion of hyphae and asexual reproduction their uptake would be rather difficult to achieve. If the mycoviruses would be sprayed onto the fields like fungicides or the Troygenics, the uptake would be estimated to be rather low in comparison.
Another topic we talked about was, if the usage of fungicides or the usage of pathogen resistant plants would be more effective to which he replied, that both are important measures of agriculture and are equally useful and necessary. Resistance genes interacting with pathogen proteins by protein-protein-interaction can be overcome by the pathogen quite easily by point mutations. Therefore, plant breeders began stacking resistance genes to lower the risk of these preventive measures losing their effect. Because plant breeding requires a lot of time, fungicides are often needed as a faster counter measure against new pathogens. However, fungicides might impact the environment and therefore must be used carefully and new, more precise versions of fungicides have to be developed. Furthermore, to lower the negative impact on the environment modern pesticides are applied at very low concentrations to fit the changing legal situation. The optimal solution to this would be perfectly working resistant plants, but for now, fungicides are still required. A well-managed mixture of both measures should be the optimal approach nowadays. We also talked about genetic engineering and its public perception and concluded, that the public discussion is often held on an emotional level. While many scientists are in favour of genetic engineering, it has also become a topic often misleadingly used for politics. The unease about genetic engineering should be evaluated critically, as people often disapprove genetically altered food while openly accepting new medications based on these methods. Moreover, there are products accepted by the society that have been produced using genetically altered organisms, like recombinant proteins, which are used in the production of cheese. However, these proteins do not require to be declared as genetic engineering. To preserve our abundant food supply, genetic engineering would represent an important tool.
For our proof of concept, we wanted to know the most common strain of wheat in our area to conduct our experiments under realistic conditions. According to Prof. Schaffrath, there is no such thing as the one most common strain of wheat for Germany. Instead, the optimal strain varies locally and from year to year as well as regarding to the location in comparison to, for example its distance to the coast. He also advised us on contacting a plant breeding companies like KWS to get access to wheat seeds, which we implemented later on during our project.
As further important crop pathogens he named Phytophthora infestans, the potato blight, and Asian Soybean Rust but also some bacteria and crop damaging insects. Besides that, he explained that fungi can have a very negative influence on trees as well. There are fungi that can destabilize trees and endanger whole species. Further, trees in cities have to be cut down regularly due to these fungi infections. Regarding pathogenic fungi for humans, he explained the problem is taking a similar course as antibiotic resistant bacteria. He suspected a higher acceptance of our system as in a medical application opposed to an agricultural tool.