Regulation and function of heat stress transcription factors and molecular chaperones in protein homeostasis

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Plant Responses to High Temperatures

Global warming has a negative impact on the yield of many crops around the globe. Currently the generation of varieties that can ensure a high and sustainable production of food is important to secure the nutrition of the growing human population. Our group aims to understand the fundamental cellular and organismic process that are activated when plants are exposed to high temperatures and reveal how they contribute to thermotolerance.

We specifically address the following questions:

How do plants respond to increased temperatures and what are the key processes that lead to thermotolerance?

Why some plant genotypes, organs, tissues or even cell types within the plant body are more sensitive to heat stress compared to others?

How can we improve the resilience of crops to high temperature and secure food production under more unfavourable environmental conditions?

Plants are able to induce defence mechanisms collectively called heat stress response to ensure survival and recovery from stress. At the molecular level, thermotolerance is mainly dependent on the maintenance of protein homeostasis which under stress conditions is accomplished by the accumulation of molecular chaperones such as many heat shock proteins (HSP). In addition to HSPs, hundreds other genes with various functions are induced under high temperatures, leading to an extensive cellular metabolic reprogramming.

Changes in transcriptome profile are mainly mediated by members of the heat stress transcription factor (Hsfs) gene family. Plants comprise a large number of Hsf-coding genes (e.g. 27 in tomato). We have demonstrated the function of three major Hsfs in tomato plant, namely HsfA1a, HsfA2 and HsfB1 in the onset of heat stress response and recovery from stress, but also in acclimation processes to high temperatures. We are currently characterizing additional members with tissue- and/or temperature-specific functions.

In addition, many Hsfs as well as other HS-regulated genes undergo alternative splicing under high temperatures. Alternative splicing controls transcriptome abundance and proteome diversity and therefore has a prominent role in thermotolerance. Consequently, we aim to uncover temperature-sensitive alternative splicing events that are related to thermotolerance and identify key factors involved in this process.

To reach our goals we engage various approaches using genetic, physiology, molecular and cell biology tools, as well as genomic approaches.

Five representative publications of our group:

Identification and Regulation of Tomato Serine/Arginine-Rich Proteins Under High Temperatures.
Rosenkranz RRE, Bachiri S, Vraggalas S, Keller M, Simm S, Schleiff E, Fragkostefanakis S. Front Plant Sci. 2021 Mar 29;12:645689. doi: 10.3389/fpls.2021.645689. PMID: 33854522; PMCID: PMC8039515.

Natural variation in HsfA2 pre-mRNA splicing is associated with changes in thermotolerance during tomato domestication.
Hu Y, Mesihovic A, Jiménez-Gómez JM, Röth S, Gebhardt P, Bublak D, Bovy A, Scharf KD, Schleiff E, Fragkostefanakis S. New Phytol. 2020 Feb;225(3):1297-1310. doi: 10.1111/nph.16221. Epub 2019 Nov 14. PMID: 31556121

The repressor and co-activator HsfB1 regulates the major heat stress transcription factors in tomato.
Fragkostefanakis S, Simm S, El-Shershaby A, Hu Y, Bublak D, Mesihovic A, Darm K, Mishra SK, Tschiersch B, Theres K, Scharf C, Schleiff E, Scharf KD. Plant Cell Environ. 2019 Mar;42(3):874-890. doi: 10.1111/pce.13434. Epub 2018 Oct 11. PMID: 30187931

Alternative splicing in tomato pollen in response to heat stress.
Keller M, Hu Y, Mesihovic A, Fragkostefanakis S, Schleiff E, Simm S. DNA Res. 2017 Apr 1;24(2):205-217. doi: 10.1093/dnares/dsw051. PMID: 28025318

HsfA2 Controls the Activity of Developmentally and Stress-Regulated Heat Stress Protection Mechanisms in Tomato Male Reproductive Tissues.
Fragkostefanakis S, Mesihovic A, Simm S, Paupière MJ, Hu Y, Paul P, Mishra SK, Tschiersch B, Theres K, Bovy A, Schleiff E, Scharf KD. Plant Physiol. 2016 Apr;170(4):2461-77. doi: 10.1104/pp.15.01913. Epub 2016 Feb 25. PMID: 26917685



Prof. Dr. Schleiff is currently the President of Goethe University Frankfurt

Head of the Group:

Dr. Sotirios Fragkostefanakis
Biozentrum, Campus Riedberg
Gebäudeteil N200, Raum 302
Max-von-Laue-Str. 9
60438 Frankfurt am Main

T +49 69 798-29287
F +49 69 798-29286

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