The wheat TdRL1 is the functional homolog of the rice RSS1 and promotes plant salt stress tolerance
Rice rss1 complementation assays show that wheat TdRL1 and RSS1 are true functional homologs. TdRL1 over-expression in Arabidopsis conferred salt stress tolerance and alleviated ROS accumulation.
Plants have developed highly flexible adaptive responses to their ever-changing environment, which are often mediated by intrinsically disordered proteins (IDP). RICE SALT SENSITIVE 1 and Triticum durum RSS1-Like 1 protein (TdRL1) are both IDPs involved in abiotic stress responses, and possess conserved D and DEN-Boxes known to be required for post-translational degradation by the APC/Ccdc20 cyclosome. To further understand their function, we performed a computational analysis to compare RSS1 and TdRL1 co-expression networks revealing common gene ontologies, among which those related to cell cycle progression and regulation of microtubule (MT) networks were over-represented. When over-expressed in Arabidopsis, TdRL1::GFP was present in dividing cells and more visible in cortical and endodermal cells of the Root Apical Meristem (RAM). Incubation with the proteasome inhibitor MG132 stabilized TdRL1::GFP expression in RAM cells showing a post-translational regulation. Moreover, immuno-cytochemical analyses of transgenic roots showed that TdRL1 was present in the cytoplasm and within the microtubular spindle of mitotic cells, while, in interphasic cells, it was rather restricted to the cytoplasm with a spotty pattern at the nuclear periphery. Interestingly in cells subjected to stress, TdRL1 was partly relocated into the nucleus. Moreover, TdRL1 transgenic lines showed increased germination rates under salt stress conditions as compared to wild type. This enhanced salt stress tolerance was associated to an alleviation of oxidative damage. Finally, when expressed in the rice rss1 mutant, TdRL1 suppressed its dwarf phenotype upon salt stress, confirming that both proteins are true functional homologs required for salt stress tolerance in cereals.
KeywordsAbiotic stress Salt RSS1 Durum wheat TdRL1 Cellular localization Oxidative stress
Author contribution statement
HM performed the experiments (expression data, cloning, transient and stable transformation of tobacco and Arabidopsis, and germination assays). YT and ST performed rice rss1 complementation assays. OBC developed the pIJBP2 vector for rice transformation. ACS and EH helped with confocal microscopy and immuno-cytochemistry experiments and analyses, and reviewed the article. CE, MH, and MEC designed the experiments, searched for funding, supervised the work, and wrote the article.
This work has been funded by the Tunisian Higher Ministry of Education and the Centre National de la Recherche Scientifique (CNRS). HM was granted from a French-Tunisian bilateral PHC-Utique program (15G0902/32601ZF). Part of this work was granted by the Swiss National Science Foundation and the ‘Mujeres for Africa’ foundation to CE. Microscopy was carried out at the Strasbourg-Esplanade cellular imaging facilities (CNRS, Université de Strasbourg, Région Alsace, Association de la Recherche sur le Cancer, and Ligue Nationale contre le Cancer).
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Conflict of interest
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
- Janski N, Masoud K, Batzenschlager M et al (2012) The GCP3-interacting proteins GIP1 and GIP2 are required for γ-tubulin complex protein localization, spindle integrity, and chromosomal stability. Plant Cell 24:1171–1187. https://doi.org/10.1105/tpc.111.094904 CrossRefPubMedPubMedCentralGoogle Scholar
- Mahjoubi H, Ebel C, Hanin M (2015) Molecular and functional characterization of the durum wheat TdRL1, a member of the conserved Poaceae RSS1-like family that exhibits features of intrinsically disordered proteins and confers stress tolerance in yeast. Funct Integr Genom 15:717–728. https://doi.org/10.1007/s10142-015-0448-x CrossRefGoogle Scholar