Poplar stem transcriptome is massively remodelled in response to single or repeated mechanical stimuli

Abstract

BackgroundTrees experience mechanical stimuli -like wind- that trigger thigmomorphogenetic syndrome, leading to modifications of plant growth and wood quality. This syndrome affects tree productivity but is also believed to improve tree acclimation to chronic wind. Wind is particularly challenging for trees, because of their stature and perenniality. Climate change forecasts are predicting that the occurrence of high wind will worsen, making it increasingly vital to understand the mechanisms regulating thigmomorphogenesis, especially in perennial plants. By extension, this also implies factoring in the recurring nature of wind episodes. However, data on the molecular processes underpinning mechanoperception and transduction of mechanical signals, and their dynamics, are still dramatically lacking in trees.ResultsHere we performed a genome-wide and time-series analysis of poplar transcriptional responsiveness to transitory and recurring controlled stem bending, mimicking wind. The study revealed that 6% of the poplar genome is differentially expressed after a single transient bending. The combination of clustering, Gene Ontology categorization and time-series expression approaches revealed the diversity of gene expression patterns and biological processes affected by stem bending. Short-term transcriptomic responses entailed a rapid stimulation of plant defence and abiotic stress signalling pathways, including ethylene and jasmonic acid signalling but also photosynthesis process regulation. Late transcriptomic responses affected genes involved in cell wall organization and/or wood development. An analysis of the molecular impact of recurring bending found that the vast majority (96%) of the genes differentially expressed after a first bending presented reduced or even net-zero amplitude regulation after the second exposure to bending.ConclusionThis study constitutes the first dynamic characterization of the molecular processes affected by single or repeated stem bending in poplar. Moreover, the global attenuation of the transcriptional responses, observed from as early as after a second bending, indicates the existence of a mechanism governing a fine tuning of plant responsiveness. This points toward several mechanistic pathways that can now be targeted to elucidate the complex dynamics of wind acclimation.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-017-3670-1) contains supplementary material, which is available to authorized users.

Sorghum tiller bud growth is repressed by contact with the overlying leaf

“…Jarin-1 had no effect on shoot elongation ( Figure S2b). 3.6 | Thigmomorphogenesis-related gene expression is altered in buds in response to leaf removal Previous studies in a diverse species have discovered transcriptional changes responsive to mechanical stimulation (Ishihara, Lee, & Borthakur, 2017;Lee et al, 2005;Pomiès, Decourteix, Franchel, Moulia, & Leblanc-Fournier, 2017). Sorghum homologs of Arabidopsis genes induced by touch (Lee et al, 2005) were identified in the set of bud genes differentially expressed in response to leaf removal.…”

Prior exposure of Arabidopsis seedlings to mechanical stress heightens jasmonic acid-mediated defense against necrotrophic pathogens

“…A single event of MS from exogenous water spray to Arabidopsis seedlings growing in artificial media or the bending of leaves from soil grown plants, has been reported to cause large-scale differential gene expression of 10 and 2.5% respectively, in naïve Arabidopsis tissues [9,10]. The majority of MS-responsive genes were implicated in cell wall modifications, hormone regulation, organelle, and calcium signalling, that collectively mediate stress acclimation responses in plants [9][10][11][12]. In the absence of MS, the expressions of most MS-responsive transcripts returned to their basal level of expression.…”

The Cytoskeleton and Its Role in Determining Cellulose Microfibril Angle in Secondary Cell Walls of Woody Tree Species

“…TW, developed on the upper side of angiosperms branches, is characterised by extremely low MFA values and this is often associated with upregulation of many of cytoskeleton component and secondary wall formation genes, including those listed previously [41,101,[104][105][106][108][109][110][111][112]. Accordingly, Li et al [113] found the same genes overexpressed in high stiffness wood in Pinus radiata, which also has lower MFA when compared to low stiffness wood.…”