Kristina Rosenzweig (Friedrich-Alexander-Universität Erlangen-Nürnberg)
Kristina Rosenzweig's Master thesis was awarded with the Prize for the Best Plant Science Master Thesis, which was carried out at Friedrich-Alexander-Universität Erlangen-Nürnberg in the year 2023 with the title:
Investigation of further resistance factors of Solanum lycopersicum against Cuscuta reflexa
The cultivated tomato Solanum lycopersicum has more than just one resistance mechanisms to defend itself against the parasitic plant Cuscuta reflexa.
Cuscuta reflexa is a parasitic plant causing severe crop and yield damage every year. The parasite has neither leaves nor roots and is therefore absolutely dependent to withdraw nutrients and water from its hosts. For that, Cuscuta builds intrerspecific connections to the hosts vasculature. The host spectrum of C. reflexa includes nearly all dicotyledonous plants. One major exception is the cultivated tomato, Solanum lycopersicum. It possesses the Cuscuta receptor 1 (CuRe1), which enables the plant to recognize Cuscuta and induces a defense response. However, there is rising evidence that CuRe1 is not the only mechanism leading to immunity.
In the course of this thesis, several candidate genes were investigated regarding their role in the defense mechanism of S. lycopersicum. More detailed, several CRISPR-Cas9 derived transgenic tomato plants were used, each having a mutation in the corresponding candidate genes. Via infection of these lines with C. reflexa, one gene could be identified whose mutation led to the loss of resistance. The identified gene encodes a protein which is part of the ethylene pathway; an important pathway playing a role in many immune responses. Further investigations via qRT-PCR experiments revealed that the gene is slightly overexpressed in the mutant plants in comparison to the resistant wildtype plants. Additionally, it was shown that the candidate gene is also upregulated in the susceptible wild tomato variety, S. pennellii. This indicates that a low expression of the gene might be related to a higher resistance. In conclusion, a possible working mechanism of the gene in the defense mechanism of S. lycopersicum has been proposed: it might be possible that an overexpression of the gene might lead to an ethylene insensitivity, resulting in a lower immune response. In contrast, a downregulation of the gene might lead to an ethylene hypersensitivity, leading to an increased immunity.
However, this hypothesis has to be verified and further experiments have to be performed regarding this research area.
___
Kristina Rosenzweig conducted this work at the Division of Molecular Plant Physiology in the group of Prof. Dr. Markus Albert.
