Biology subjects

Pantazopoulou, C. K.

Publications and source records attributed to Pantazopoulou, C. K..

6 recordsLinked to original sources

bioRxiv2024

Brassinosteroid and gibberellin signaling are required for Tomato internode elongation in response to low red: far-red light

In this study, we explore the dynamic interplay between the plant hormones gibberellins (GA), brassinosteroids (BR), and Indole-3-Acetic Acid (IAA) in their collective impact on plant shade avoidance elongation under varying light conditions. We focus particularly on low Red: Far-red (R:FR) light conditions achieved by supplementing the background light with FR. Our research delves into how these hormones individually and synergistically influence stem elongation in tomato plants. Through meticulous experimental modulations of GA, IAA, and BR, we demonstrate that GA and BR are sufficient but also necessary for inducing stem elongation under low R:FR light conditions. Intriguingly, while IAA alone shows limited effects, its combination with GA yields significant elongation, suggesting a nuanced hormonal balance. Furthermore, we unveil the complex interplay of these hormones under light with low R:FR, where the suppression of one hormones effect can be compensated by the others. This study provides insights into the hormonal mechanisms governing plant adaptation to light, highlighting the intricate and adaptable nature of plant growth responses. Our findings have far-reaching implications for agricultural practices, offering potential strategies for optimizing plant growth and productivity in various lighting environments. HighlightThis study unveils the interplay of brassinosteroids and gibberellins in shade avoidance elongation, revealing how tomatoes acclimate in response to far-red enriched light conditions.

plant biology↗

bioRxiv2023

A low-cost and open-source imaging platform reveals spatiotemporal insight into Arabidopsis leaf elongation and movement

Plant organs move throughout the diurnal cycle, changing leaf and petiole positions to balance light capture, leaf temperature and water loss under dynamic environmental conditions. Upward movement of the petiole, called hyponasty, is one of several traits of the shade avoidance syndrome (SAS). SAS traits are elicited upon perception of vegetation shade signals such as far-red light (FR) and improve light capture in dense vegetation. Monitoring plant movement at a high temporal resolution allows studying functionality, as well as molecular regulation of hyponasty. However, high temporal resolution imaging solutions are often very expensive, making this unavailable to many researchers. Here, we present a modular and low-cost imaging set-up, based on small Raspberry Pi computers, that can track leaf movements and elongation growth with high temporal resolution. We also developed an open-source, semi-automated image analysis pipeline. Using this setup we followed responses to FR enrichment, light intensity and their interactions. Tracking both elongation and angle of petiole, lamina and entire leaf revealed insight into R:FR sensitivities of leaf growth and movement dynamics, and its interactions with background light intensity. We also identified spatial separation in hyponastic response regulation for the petiole and the lamina of the leaf, depending on the light conditions.

plant biology↗

bioRxiv2022

Local light signalling at the leaf tip drives remote differential petiole growth through auxin-gibberellin dynamics

Although plants are immobile, many of their organs are flexible to move in response to environmental cues. In dense vegetation plants detect neighbours through far-red light perception with their leaf tip. They respond remotely, with asymmetrical growth between the abaxial and adaxial sides of the leafstalk, the petiole. This results in upward movement that brings the leaf blades into better lit zones of the canopy. The plant hormone auxin is required for this response, but it is not understood how non-differential leaf tip-derived auxin can remotely regulate movement. Here we show that remote light signalling promotes auxin accumulation in the abaxial petiole by reinforcing an intrinsic auxin transport directionality. In the petiole, auxin elicits a response of both auxin as well as a second growth promoter; gibberellin. We show that this dual regulation is necessary for hyponastic leaf movement in response to light. Our results reveal how plants can spatially relay information about neighbour proximity from their sensory leaf tips to the petiole base, thus driving adaptive growth.

plant biology↗

bioRxiv2022

Mechanodetection of neighbor plants elicits adaptive leaf movements through calcium dynamics

Plants detect their neighbors via various cues, including reflected light and touching of leaf tips, which elicit in upward leaf movement (hyponasty). It is currently unknown how touch is sensed and how the signal is transferred from the leaf tip to the petiole base that drives hyponasty. Here, we show that touch-induced hyponasty involves a signal transduction pathway that is distinct from light-mediated hyponasty. We found that mechanostimulation of the leaf tip upon touching causes cytosolic calcium ([Ca2+]cyt induction in leaf tip trichomes that spreads towards the petiole. Both perturbation of the calcium response and the absence of trichomes inhibit touch-induced hyponasty. Finally, using plant competition assays, we show that touch-induced hyponasty is adaptive in dense stands of Arabidopsis. We thus establish a novel, adaptive mechanism regulating hyponastic leaf movement in response to mechanostimulation by neighbors in dense vegetation.

plant biology↗

bioRxiv2020

A gas-and-brake mechanism of bHLH proteins modulates shade avoidance in Arabidopsis thaliana

Plants detect proximity of competitors through reduction in the ratio between red and far red light triggering the shade avoidance syndrome, which includes accelerated shoot elongation and early flowering. Shade avoidance is regulated through PHYTOCHROME INTERACTING FACTORs (PIFs), a group of bHLH transcription factors. Another (b)HLH protein, KIDARI (KDR), which is non-DNA-binding, was identified in de-etiolation studies and proposed to interact with LONG HYPOCOTYL IN FAR-RED 1 (HFR1), a (b)HLH protein that inhibits shade avoidance. Here we establish novel roles of KDR in regulating shade avoidance and investigate how KDR regulates the shade avoidance network. We show that KDR is a positive regulator of shade avoidance and interacts with several negative growth regulators. We identify novel interactors using a combination of yeast two-hybrid screening and dedicated confirmations with bimolecular fluorescence complementation. We demonstrate that KDR is translocated primarily to the nucleus when coexpressed with these newly discovered interactors. A genetic approach confirmed that several of these novel interactions are indeed functional to shade avoidance in Arabidopsis thaliana, whereas we propose that KDR does not interact with HFR1 to regulate shade avoidance. Based on this, we propose that shade avoidance is regulated by a three-layered gas-and-brake mechanism of bHLH protein interactions, adding an additional layer of complexity to what was previously known. One-sentence summaryKIDARI is a positive regulator of shade avoidance and part of a three-layer network of bHLH transcription factor interactions.

plant biology↗

bioRxiv2019

Reducing shade avoidance can improve Arabidopsis canopy performance against competitors

The loss of crop yield due to weeds is an urgent agricultural problem. Although herbicides are an effective way to control weeds, more sustainable solutions for weed management are desirable. It has been proposed that crop plants can communally suppress weeds by shading them out. Shade avoidance responses, such as upward leaf movement (hyponasty) and stem or petiole elongation, enhance light capture of individual plants, increasing their individual fitness. The shading capacity of the entire crop community might, however, be more effective if aspects of shade avoidance are suppressed. Testing this hypothesis in crops is hampered by the lack of well-characterized mutants. We therefore investigated if Arabidopsis competitive performance at the community level against invading competitors is affected by the ability to display shade avoidance. We tested two mutants: pif4pif5 that has mildly reduced petiole elongation and hyponasty and pif7 with normal elongation but absent hyponasty in response to shade. Although pif4pif5 performed similar to wildtype, we found that pif7 showed significantly increased canopy biomass and suppression of invading competitors as compared to its wildtype. Our data thus show that modifying specific shade avoidance aspects has potential for plant community performance. This may help to suppress weeds in crop stands.\n\nHighlightHyponastic response in canopies facilitates light penetration and weed growth. Inhibition of this response to neighbors increased canopy biomass, canopy closure and suppression of competitors.

plant biology↗