DBG · Promoting young researchers

Tobias Blank (Leibniz Universität Hannover)

Tobias Blank's Master thesis was awarded with the Prize for the Best Plant Science Master Thesis, which was carried out at Leibniz Universität Hannover in the year 2023 with the title:

Analysis of secondary metabolites and their response to salinity in hairy roots of Lycium humile.

For the first time Tobias Blank analysed adaptive strategies of the extreme halophyte Lycium humile to saline environments on a metabolic level. He established hairy root cultures and exposed them to varying salinity, enabling detailed measurement of secondary metabolites in response to salt stress.

The increasing salinization of soils is a major global challenge, which requires innovative strategies for researching plant salt tolerance. This study focused on the largely unexplored halophyte species Lycium humile. This plant occurs naturally only in the high mountains and salt deserts of the Andes, South America. To investigate the mechanisms of salt tolerance of Lycium humile, we induced hairy root cultures using the bacterium Rhizobium rhizogenes. This technique enabled the growth of roots in a controlled environment and is ideally suited for studying plant responses to stress, especially given the strictly limited plant material. Three of these hairy root lines were then cultured in liquid media with varying concentrations of salt to simulate the challenging conditions these plants face in nature.

The experiment focused on analyzing the production of secondary metabolites in the roots, which could be crucial for the resilience of Lycium humile. The total amounts of phenolics, flavonoids, and alkaloids were measured. To gain a comprehensive understanding of these metabolic changes, Liquid Chromatography-Mass Spectrometry (LC-MS) was also employed. It was demonstrated that the total content of phenolics and flavonoids was increased in one of the hairy root lines under salt stress. Further significant shifts in secondary metabolites were revealed by the results of the LC-MS.

For the first time, this provided an insight into how the extremely halophilic Lycium humile chemically responds to salt. Whether the experiments with the hairy root cultures reflect the actual mechanisms of the whole plant and which compounds are involved in detail need to be determined in future experiments.


Tobias Blank conducted the thesis at the Institute of Botany in Prof. Dr. Jutta Papenbrock's working group.

> photo of the working group

(A) Lycium humile in its natural habitat in the Andes, South America (picture kindly provided by Virginia Palchetti). (B) An established hairy root culture of L. humile. (C) Results of the measurement of the total flavonoid content of a hairy root line after 7 days of culture in saline media. Values are expressed in catechin equivalents (CE) per mg fresh weight (FW) (mean ± SD, n=3). Values sharing the same letters do not differ significantly from each other according to Tukey's pairwise post-hoc test (p < 0.05).
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