Martina Legris

• PhD
• PostDoc Position at University of Lausanne

Canopy shade enhances the activity of PHYTOCHROME INTERACTING FACTORs (PIFs) to boost auxin synthesis in the cotyledons. Auxin, together with local PIFs and their positive regulator CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1), promotes hypocotyl growth to facilitate access to light. Whether shade alters the cellular redox status thereby affecting grow...

In plants, light direction is perceived by the phototropin photoreceptors, which trigger directional growth responses known as phototropism. The formation of a phototropin activation gradient across a photosensitive organ initiates this response. However, the optical tissue properties that functionally contribute to phototropism remain unclear. In...

Leaves are the main photosynthetic organs in plants, and their anatomy is optimized for light interception and gas exchange. Although each species has a characteristic leaf anatomy, which depends on the genotype, leaves also show a large degree of developmental plasticity. Light and temperature regulate leaf development from primordia differentiati...

PHYTOCHROME KINASE SUBSTRATE (PKS) proteins are involved in light-modulated changes in growth orientation. They act downstream of phytochromes to control hypocotyl gravitropism in the light and act early in phototropin signaling. Despite their importance for plant development, little is known about their molecular mode of action, except that they b...

In light-limiting conditions, aerial organs of most plants reorient their growth towards the light to improve photosynthesis, through a process known as phototropism (1-3). The blue light receptors phototropin control phototropic responses through light-induced protein kinase activity (4). Current models posit that asymmetric activation of these se...

Plants undergo transcriptome reprogramming to adapt to daily and seasonal fluctuations in light and temperature conditions. While most efforts have focused on the role of master transcription factors, the importance of splicing factors modulating these processes is now emerging. Efficient pre-mRNA splicing depends on proper spliceosome assembly, wh...

As the summer approaches, plants experience enhanced light inputs and warm temperatures, two environmental cues with an opposite morphogenic impact. Key components of this response are PHYTOCHROME B (phyB), EARLY FLOWERING 3 (ELF3), and CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1). Here, we used single and double mutant/overexpression lines to fit a math...

Plants undergo transcriptome reprogramming to adapt to daily and seasonal fluctuations in light and temperature conditions. While most efforts have focused on the role of master transcription factors, the importance of splicing factors modulating these processes is now emerging. Efficient pre-mRNA splicing depends on proper spliceosome assembly, wh...

As the summer approaches, plants experience enhanced light inputs and elevated temperatures, two environmental cues with an opposite morphogenic impact. How plants integrate this conflicting information throughout seasons remains unclear. Key components of the plant response to light and temperature include phytochrome B (phyB), PHYTOCROME INTERACT...

One conserved feature among angiosperms is the development of flat thin leaves. This developmental pattern optimizes light capture and gas exchange. The blue light receptors phototropins are required for leaf flattening, with the null phot1phot2 mutant showing curled leaves in Arabidopsis (Arabidopsis thaliana). However, key aspects of their functi...

One conserved feature among angiosperms is the development of flat thin leaves. This developmental pattern optimizes light capture and gas exchange for photosynthesis. The blue light receptors phototropins are required for leaf flattening, with the null phot1phot2 mutant showing downwards curled leaves in Arabidopsis. However, key aspects of their...

Shade-avoiding plants, including Arabidopsis (Arabidopsis thaliana), display a number of growth responses, such as elongation of stem-like structures and repositioning of leaves, elicited by shade cues, including a reduction in the blue and red portions of the solar spectrum and a low red to far-red ratio. Shade also promotes phototropism of de-eti...

Significance DELLA proteins are plant-specific transcriptional regulators that act as signaling hubs at the interface between the environment and the transcriptional networks that control growth. The growth-promoting hormone gibberellin destabilizes DELLAs. Here we describe an alternative pathway to destabilize these proteins. We show that DELLAs a...

Positive phototropism is the process through which plants orient their organs towards a directional light source. While the blue light receptors phototropins (phot) play a major role in phototropism towards blue (B) and ultraviolet (UV) radiation, recent research showed that the UVB light receptor UVR8 also triggers phototropism towards UVB. In add...

Shade-avoiding plants including Arabidopsis thaliana display a number of growth responses elicited by shade cues including elongation of stem-like structures and repositioning of leaves. Shade also promotes phototropism of de-etiolated seedlings through repression of phytochrome B (phyB) presumably to enhance capture of unfiltered sunlight. Light c...

DELLA transcriptional regulators are central components in the control of plant body form in response to the environment. This is considered to be mediated by changes in the metabolism of the hormones gibberellins (GAs), which promote the degradation of DELLAs. However, here we show that warm temperature or shade reduced the stability of a GA-insen...

Phytochromes are bilin-binding photosensory receptors which control development over a broad range of environmental conditions and throughout the whole plant life cycle. Light-induced conformational changes enable phytochromes to interact with signaling partners, in particular transcription factors or proteins that regulate them, resulting in large...

Due to the preeminence of reductionist approaches, understanding of plant responses to combined stresses is limited. We speculated that light‐quality signals of neighboring vegetation might increase susceptibility to heat shocks because shade reduces tissue temperature and hence the likeness of heat shocks. In contrast, plants of Arabidopsis thalia...

Vegetation shade is characterised by marked decreases in the red/far-red ratio and photosynthetic irradiance. The activity of phytochrome in the field has typically been described by its photoequilibrium, defined by the photochemical properties of the pigment in combination with the spectral distribution of the light. This approach represents an ov...

Due to the preeminence of reductionist approaches, our understanding of plant responses to combined stresses is limited. We speculated that light-quality signals of neighboring vegetation might increase susceptibility to heat shocks because shade reduces tissue temperature and hence the likeness of heat shocks. In contrast, plants of Arabidopsis th...

Agricultural crops are exposed to a range of daylengths, which act as important environmental cues for the control of developmental processes such as flowering. To explore the additional effects of daylength on plant function, we investigated the transcriptome of Arabidopsis plants grown under short days (SD) and transferred to long days (LD). Comp...

Significance In agricultural crops, plants are cultivated in close proximity, exposed to mutual shading. Photosensory receptors perceive this light environment and initiate growth responses that adjust the position of plant organs within the canopy to maximize light capture. During the early hours under shade, these responses are mediated by elevat...

Light and temperature patterns often correlate in natural plant growth conditions. In this review, we analyse the perception and signalling mechanisms shared by both of these environmental cues and discuss the functional implications of their convergence to control plant growth. The first point of integration is the phytochrome B (phyB) receptor, w...

Combining heat and light responses Plants integrate a variety of environmental signals to regulate growth patterns. Legris et al. and Jung et al. analyzed how the quality of light is interpreted through ambient temperature to regulate transcription and growth (see the Perspective by Halliday and Davis). The phytochromes responsible for reading the...

Shade‐avoidance responses require CONSTITUTIVE PHOTOMORPHOGENESIS 1 ( COP 1) but the mechanisms of action of COP 1 under shade have not been elucidated. Using simulated shade and control conditions, we analysed: the transcriptome and the auxin levels of cop1 and phytochrome interacting factor 1 ( pif1 ) pif3 pif4 pif5 ( pifq ) mutants; the dynamics...

The current consensus is that plant responses to canopy shade involve the perception of low red to far-red ratios (R:FR) by phytochrome B (phyB), which leads to the direct activation of auxin synthesis genes by PHYTOCHROME INTERACTING FACTORS (PIF). In addition to its effect on R:FR, shade also reduces irradiance, but whether shade-induced drops in...

In darkness, the E3 ligase COSTITUTIVE PHOTOMORPHOGENESIS 1 (COP1) targets to degradation ELONGATED HYPOCOTYL 5 (HY5) and other proteins required for photomorphogenesis (Osterlund et al., 2000; Saijo et al., 2003; Seo et al., 2003). Light inactivates COP1, allowing photomorphogenesis to proceed (Lau and Deng, 2012). Pioneer studies have demonstrate...

Moderately warm constant ambient temperatures tend to oppose light signals in the control of plant architecture. By contrast, here we show that brief heat shocks enhance the inhibition of hypocotyl growth induced by light perceived by phytochrome B in deetiolating Arabidopsis thaliana seedlings. In darkness, daily heat shocks transiently increased...

Shade-avoider plants typically respond to shade-light signals by increasing the rate of stem growth. CONSTITTUTIVE PHOTOMORPHOGENESIS 1 (COP1) is an E3 ligase involved in ubiquitin labelling of proteins targeted for degradation. In dark-grown seedlings, COP1 accumulates in the nucleus and light exposure causes COP1 migration to the cytosol. Here we...