210 research outputs found
Environmental stress and flowering time: the photoperiodic connection
No full textPlants maximize their chances to survive adversities by reprogramming their development according to environmental conditions. Adaptive variations in the timing to flowering reflect the need for plants to set seeds under the most favorable conditions. A complex network of genetic pathways allows plants to detect and integrate external (e.g., photoperiod and temperature) and/or internal (e.g., age) information to initiate the floral transition. Furthermore different types of environmental stresses play an important role in the floral transition. The emerging picture is that stress conditions often affect flowering through modulation of the photoperiodic pathway. In this review we will discuss different modes of cross talk between stress signaling and photoperiodic flowering, highlighting the central role of the florigen genes in this process.Matteo Riboni, Alice Robustelli Test, Massimo Galbiati, Chiara Tonelli & Lucio
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THE ROLE OF ABA IN THE FLORAL TRANSITION: SITE AND MECHANISM OF ACTION
No full textThe reproductive success of plants depends on their developmental plasticity that is the ability to modulate their growth in response to exogenous and endogenous stimuli. Plants efficiently integrate these signals to coordinate their life cycle according to the best conditions to increase their fitness. Light and water availability is a limiting factor for plants sustenance and growth. In Arabidopsis thaliana day length (photoperiod) and water status influence flowering time. In particular, water deficit accelerates flowering thus enabling the drought escape (DE) responses. Interestingly, such DE responses only occurs under inductive long day conditions (LDs, typical of spring and summer seasons) but not short day conditions (SDs) highlighting a link between photoperiod perception and drought responses. The phytohormone abscisic acid (ABA) mediates the DE response, by promoting the upregulation of the florigen genes FLOWERING LOCUS T (FT) and its paralogue TWIN SISTER OF FT (TSF), whose expression is activated mainly by LDs. The role of ABA in flowering regulation is controversial as the literature describes both positive and negative roles for ABA in flowering. My PhD work supports the idea that ABA acts as florigen-stimulating molecule under LDs and its activity depends on prior activation of the photoperiodic pathway. I demonstrated that the ABA-dependent activation of FT requires GIGANTEA (GI) and CONSTANS (CO) functions, two main components of the photoperiodic pathway that control florigen expression. The generation of transgenic plants over-expressing tagged versions of GI or CO proteins in different ABA genetic backgrounds allowed me to directly asses their activity and measure their accumulations under varying levels of ABA signalling. My results indicate that ABA promotes GI and CO function without affecting their protein stability. An intriguing perspective of my work is that ABA might regulate GI and/or CO accessibility to the FT promoter. Further studies are however necessary to test this hypothesis and to decipher the molecular mechanism by which ABA allow plants to coordinate flowering time according to the prevailing watering conditions
Linear white lesion in the oral mucosa
No full textTwo unrelated patients aged 60 and 61 presented with an asymptomatic, white, slightly raised line on the buccal mucosa extending bilaterally from the commissure to the last molar teeth along their occlusal line, involving also the inner lower lip mucosa (Fig 1, A and B). The lesions could not wipe off on scratching. Medical history was unremarkable. Histopathology showed hyperparakeratosis without granular layers and regular acanthosis vacuolated cells in the upper spinous cell layer with some dyskeratotic cells in the absence of dysplasia (Fig 2). Neither inflammatory infiltrate nor bacterial colonies attached to the surface or fungal elements were seen (Fig 3)
Acute generalized exanthematous pustulosis with erythema multiforme‐like lesions induced by Hydroxychloroquine in a woman with coronavirus disease 2019 (COVID‐19)
No full textMolecular Basis of the ABA Dependent Modulation of CONSTANS Activity in Drought Escape Response
No full textPlants ability to adapt their development in response to environmental changes is one key factor underlying their evolutionary success. Phytohormones modulate different plant–environment interactions, namely the regulation of flowering time that is crucial to synchronize the onset of the reproductive phase with the most favorable conditions. In Arabidopsis thaliana the plant hormone abscisic acid (ABA), known to regulate various drought stress responses, promotes flowering under long day but not short day conditions. Genetic analyses support a model where ABA signals interact with the photoperiodic pathway, upstream of the flowering gene FLOWERING LOCUS T. Aims of my project are to define how ABA and photoperiod signaling interact. My genetic data indicates that ABA promotes flowering by modulating the activity of the FT activator CONSTANS (CO) rather than its transcriptional regulation. Initial data about the molecular basis of this ABA–CO interaction will be presented. Our study point to CO as the key integrator between ABA signals and the photoperiodic pathway, allowing plants to coordinate flowering time according to the prevailing watering conditions
Histologic features of long‐lasting chilblain‐like lesions in a paediatric COVID‐19 patient
No full textCoronavirus disease 2019 (COVID-19) rash in a psoriatic patient treated with Secukinumab: Is there a role for Interleukin 17?
No full textABA-dependent control of GIGANTEA signalling enables drought escape via up-regulation of FLOWERING LOCUS T in Arabidopsis thaliana
No full textOne strategy deployed by plants to endure water scarcity is to accelerate the transition to flowering adaptively via the drought escape (DE) response. In Arabidopsis thaliana, activation of the DE response requires the photoperiodic response gene GIGANTEA (GI) and the florigen genes FLOWERING LOCUS T (FT) and TWIN SISTER OF FT (TSF). The phytohormone abscisic acid (ABA) is also required for the DE response, by promoting the transcriptional up-regulation of the florigen genes. The mode of interaction between ABA and the photoperiodic genes remains obscure. In this work we use a genetic approach to demonstrate that ABA modulates GI signalling and consequently its ability to activate the florigen genes. We also reveal that the ABA-dependent activation of FT, but not TSF, requires CONSTANS (CO) and that impairing ABA signalling dramatically reduces the expression of florigen genes with little effect on the CO transcript profile. ABA signalling thus has an impact on the core genes of photoperiodic signalling GI and CO by modulating their downstream function and/or activities rather than their transcript accumulation. In addition, we show that as well as promoting flowering, ABA simultaneously represses flowering, independent of the florigen genes. Genetic analysis indicates that the target of the repressive function of ABA is the flowering-promoting gene SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1), a transcription factor integrating floral cues in the shoot meristem. Our study suggests that variations in ABA signalling provide different developmental information that allows plants to co-ordinate the onset of the reproductive phase according to the available water resources
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