Temperatur-abhängige Veränderungen der Aktivität von Hitzestresstranskriptionsfaktoren durch alternatives Spleißen
Zell- und Entwicklungsbiologie der Pflanzen
Zusammenfassung der Projektergebnisse
Exposure to high temperatures can cause heat stress and have negative effect on plant growth and development. Survival and recovery from stress require the activation of heat stress response, a set of gene networks that activate mainly genes which code for proteins with protective functions for cellular structures and macromolecules. Among them the best studied are heat shock proteins (HSPs). The induction of HSPs but also hundreds of other heat stress responsive genes is regulated by the activity of heat stress transcription factors (HSFs). In tomato, the model plant of this study, 24 HSF genes have been discovered. The abundance and activity of HSFs are subjected to multiple levels of regulation, including transcription, premRNA splicing, post-translational modifications, interactions with other proteins and degradation. We have identified that two stress induced tomato HSFs, namely HsfA2 and HsfA7 are subjected to temperature-dependent alternative splicing. This results into the generation of protein isoforms with distinct functions: (a) Intron retention results in the generation of isoform I RNA that upon translation generates a protein with a nuclear export (NES) signal in the C-terminus of the protein; (b) Instead, intron splicing results in protein isoforms (HsfA2-II, HsfA7-II, HsfA7-III) that lack an NES. We have shown that the presence of the NES is important for the retention of the protein of the proteins in the cytosol during recovery from stress, their protection against degradation from nuclear 26S proteasome and their rapid activation in cases of a recurring heat stress incident. Analysis of a large population of different tomato accessions covering all rang of tomato domestication history from wild species to modern cultivars showed the selection of a HsfA2 haplotype that favours intron retention and HsfA2-I generation. This has led to a better acclimation capacity of tomato cultivars to heat stress compared to their wild ancestors. We have further showed that the mutants show weak thermomemory capacity, 3 days after a priming stress treatment. To analyse in more detail the functional relevance of the isoforms of the two genes, we have complemented the mutant lines with an expression cassette for each isoform of the corresponding gene fused to GFP driven by the endogenous promoter. Our results indicate that only isoform I can recover the sensitive mutant thermomemory phenotype back to wild type levels. Altogether, our results highlight the importance of temperature sensitive alternative splicing for the regulation of thermotolerance, and particularly acclimation and thermomemory.
Projektbezogene Publikationen (Auswahl)
-
Natural variation in HsfA2 pre‐mRNA splicing is associated with changes in thermotolerance during tomato domestication. New Phytologist, 225(3), 1297-1310.
Hu, Yangjie; Mesihovic, Anida; Jiménez‐Gómez, José M.; Röth, Sascha; Gebhardt, Philipp; Bublak, Daniela; Bovy, Arnaud; Scharf, Klaus‐Dieter; Schleiff, Enrico & Fragkostefanakis, Sotirios
-
Identification and Regulation of Tomato Serine/Arginine-Rich Proteins Under High Temperatures. Frontiers in Plant Science, 12.
Rosenkranz, Remus R. E.; Bachiri, Samia; Vraggalas, Stavros; Keller, Mario; Simm, Stefan; Schleiff, Enrico & Fragkostefanakis, Sotirios
-
HsfA7 coordinates the transition from mild to strong heat stress response by controlling the activity of the master regulator HsfA1a in tomato. Cell Reports, 38(2), 110224.
Mesihovic, Anida; Ullrich, Sarah; Rosenkranz, Remus R.E.; Gebhardt, Philipp; Bublak, Daniela; Eich, Hannah; Weber, Daniel; Berberich, Thomas; Scharf, Klaus-Dieter; Schleiff, Enrico & Fragkostefanakis, Sotirios
