Biology subjects

Desnos, T.

Publications and source records attributed to Desnos, T..

3 recordsLinked to original sources

bioRxiv2023

Correlation between plant cell wall stiffening and root extension arrest phenotype in the combined abiotic stress of Fe and Al

The plasticity and growth of plant cell walls (CWs) remain poorly understood at the molecular level. In this work, we used atomic force microscopy (AFM) to observe elastic responses of the root transition zone of 4-day-old Arabidopsis thaliana wild type and almt1 mutant seedlings grown under Fe or Al stresses. The elastic parameters were deduced from force-distance measurements by AFM using the trimechanic-3PCS framework. In all metal stresses tested, the presence of single metal species Fe2+ or Al3+ at 10 {micro}M exerts no noticeable effect on the root growth compared with the control conditions. On the contrary, a mix of both the metal ions produced a strong root extension arrest concomitant with significant increase of CW stiffness. This was not found for the almt1 mutant which substantially abolishes the ability to exude malate. By raising the concentration of either Fe2+ or Al3+ to 20 {micro}M, no root extension arrest was observed; nevertheless, a rise of root stiffness occurred. Our results indicate that the combination of Fe2+ and Al3+ with exuded malate is crucial for both CW stiffening and root extension arrest. However, stiffness increase induced by single Fe or Al metal is not sufficient for arresting root growth. Summary statementWe record the change in stiffness of the external primary cell wall of living Arabidopsis thaliana seedlings in presence of metallic stress using atomic force microscopy. Results reveals for the first time the uncoupling between mechanical response (CW stiffening) and root extension arrest.

plant biology↗

bioRxiv2020

Arabidopsis Casein Kinase 2 triggers Stem Cell Exhaustion under Al Toxicity and Phosphate Deficiency Through activation of the DNA Damage Response pathway

Aluminum (Al) toxicity and inorganic phosphate (Pi) limitation are widespread chronic abiotic and mutually enhancing stresses that profoundly affect crop yield. Both stresses cause a strong inhibition of root growth, resulting from a progressive exhaustion of the stem cell niche. Here, we report on a casein kinase 2 (CK2) inhibitor identified by its capability to maintain a functional root stem cell niche under Al toxic conditions. CK2 operates through phosphorylation of the cell cycle checkpoint activator SUPPRESSOR OF GAMMA RADIATION1 (SOG1), priming its activity under DNA-damaging conditions. In addition to yielding Al tolerance, CK2 and SOG1 inactivation prevents meristem exhaustion under Pi starvation, revealing the existence of a low Pi-induced cell cycle checkpoint that depends on the DNA damage activator ATAXIA-TELANGIECTASIA MUTATED. Overall, our data reveal an important physiological role for the plant DNA damage response pathway under agriculturally limiting growth conditions, opening new avenues to cope with Pi limitation. ONE-SENTENCE SUMMARYCasein kinase 2 and DNA damage response regulators play a pivotal role in the control of Arabidopsis root growth in response to Al toxicity and phosphate limitation.

plant biology↗

bioRxiv2019

Two ecotype-related long non-coding RNAs in the environmental control of root growth

BackgroundRoot architecture varies widely between species and even between ecotypes of the same species despite the strong conservation of the protein-coding portion of their genomes. In contrast, non-coding RNAs evolved rapidly between ecotypes and may control their differential responses to the environment as several long non-coding RNAs (lncRNAs) can quantitatively regulate gene expression.\n\nResultsRoots from Columbia (Col) and Landsberg erecta (Ler) ecotypes respond differently to phosphate starvation. We compared complete transcriptomes (mRNAs, lncRNAs and small RNAs) of root tips from these two ecotypes during early phosphate starvation. We identified thousands of new lncRNAs categorized as intergenic or antisense RNAs that were largely conserved at DNA level in these ecotypes. In contrast to coding genes, many lncRNAs were specifically transcribed in one ecotype and/or differentially expressed between ecotypes independently of the phosphate condition. These ecotype-related lncRNAs were characterized by analyzing their sequence variability among plants and their link with siRNAs. Our analysis identified 675 lncRNAs differentially expressed between the two ecotypes including specific antisense RNAs targeting key regulators of root growth responses. Mis-regulation of several intergenic lncRNAs showed that at least two ecotype-related lncRNAs regulate primary root growth in Col.\n\nConclusionsThe in depth exploration of the non-coding transcriptome of two ecotypes identified thousands of new lncRNAs showing specific expression in root apexes. De-regulation of two ecotype-related lncRNAs revealed a new pathway involved in the regulation of primary root growth. The non-coding genome may reveal novel mechanisms involved in ecotype adaptation of roots to different soil environments.

plant biology↗