Portrait photo of Petra Marhava standing in an in vitro growth room fetching a square plate with green Arabidopsis seedlings

Marhava, Petra - Plant acclimation to heat and cold stress

Research

Portrait photo of Petra Marhava standing in an in vitro growth room fetching a square plate with green Arabidopsis seedlingsPhoto: Andreas Palmén

Temperatures below or above the physiological optimum for plant growth induce temperature stress, which can cause detrimental and irreversible damage to plant growth and development. While most of the studies to date have focused on big-picture elements of plant responses to climate change, our research will provide insights into the molecular and cellular responses, to improve our mechanistic understanding of plant acclimation to heat and cold stress.

Even though studies on the underlying mechanisms of plant acclimation to high/low temperature are making steady progress, many questions remain unanswered. In particular, the role of the plant root system during acclimation to temperature stress has received little attention, though temperature stress at the root level can strongly affect the function of the whole plant and decrease crop productivity. In addition, despite knowing that plants show organ-specific transcriptome responses to temperature stress, we still tend to generalize findings based on shoot tissues. In my group, we combine state-of-the-art techniques for exploring root tissue to understand how roots sense and modulate their growth in response to fluctuating temperatures.

Portrait photo of Catherine Bellini wearing a white jacket and a colourful scarf. She has short dark hair.

Bellini, Catherine - Control of Adventitious Root Initiation and Phloem Function

Research

Portrait photo of Catherine Bellini wearing a white jacket and a colourful scarf. She has short dark hair. Photo: Mattias Pettersson, Umeå University

My research focusses on two different areas using the plant model system Arabidopsis thaliana, and more recently hybrid aspen and Norway spruce. The first project which is developed at the Umeå Plant Science Center, aims at tackling the regulation of adventitious root initiation, which is a key limiting step during vegetative propagation of economically important tree species.
The second aspect, which started at the UPSC, but is now pursued in the CATS group (Carbon Allocation Transport and Signaling) headed by Dr. Sylvie Dinant at the Jean-Pierre Bourgin Institute (IJPB, from the INRAE centre in Versailles, France) focus more specifically on sugar transport and carbon allocation, and their role on plant development and interaction with the environment.

Deciphering molecular cross-talks that control adventitious root initiation

Adventitious roots (AR) are roots that develop on any organs but roots and are required for vegetative propagation of plants. Their initiation and development are limiting steps for the clonal propagation of many economically important tree species. They initiate from differentiated cells of aerial plant organs following several steps that include cell dedifferentiation, reprogramming, division and differentiation. Adventitious rooting is a quantitative genetic trait with a high phenotypic plasticity due to multiple endogenous and environmental regulatory factors. We used Arabidopsis as a model system to decipher the molecular cross-talks that control AR initiation. We have identified regulatory genes acting at several levels, including subunits of the COP9 signalosome (CSN) required for protein degradation, genes acting at the crosstalk of auxin, jasmonate and cytokinin signalling pathways. We are also interested in understanding how light signalling interacts with hormone signalling in the regulation of AR initiation. In parallel we study AR initiation in hybrid aspen, hybrid poplar and Norway spruce seedlings. In the frame of proof-of-concept projects we confirmed that the genes identified in the model system Arabidopsis, play a role in adventitious root formation in poplar cutting meaning that our basic research could lead to improvement of vegetative propagation of horticultural and forest species.

Collage of two photos showing on the left Arabidopsis seedlings from the side on a black background and on the right poplar cuttings growing in a box on transparent culture medium and pictured from below Left: Arabidopsis etiolated seedlings showing adventitious roots on the hypocotyl (adapted from Gutierrez et al 2009, Plant Cell); right: Adventitious roots on in vitro poplar cuttings (photo: Sanaria Alallaq)Schematic model showing the involved molecular components involved in adventitious root initiationTIR1/AFB2-Aux/IAA6/9/17-ARF6/8 and ARF17 signaling module is involved in the control of adventitious root initiation upstream of GH3.3, GH3.5 and GH3. (adapted from Lakehal et al. 2019; https://doi.org/10.1016/j.molp.2019.09.001)

Carbon allocation, transport and signaling (CATS team, IJPB)

In land plants, carbon allocation from the photosynthetic organs to the other organs is an integrative process enabling the plant to adjust the delivery of carbon and energetic resources depending on the plant development and environmental constraints. Thereby, carbon allocation coordinates use and storage of sugars at various scales, from the cell to the whole organism. Our goal is to determine, in the different plant organs, the mechanisms acting at a cellular, tissue and organ levels for the allocation of carbohydrates. We focus on the gene networks involved in this process and their coupling with other nutritional and developmental mechanisms, in relationship with adaptive anatomic and metabolic adjustments.

Collage of five microscope pictures of stem sections in coloured in red (left photo) and showing phloem and xylem tissues on the right photos either with lower resolution on the top and with higher resolution on the bottom. Left: Confocal image of a cross section of the basal part of the floral stem from a wild-type plant. The section was stained with blue alcian and Safranin O, and its autofluorescence was collected between 512-590 nm. (Photo: Rozenn Le Hir); right: The SWEET11-1 and SWEET12-1 genes are expressed in the phloem and the xylem tissues (Le Hir et al., 2015 Mol Plant 8, 11: 1687-1690). ph: phloem, xy: xylem.

Key Publications

  • Lakehal A, Dod A, Raneshan Z, Alallaq S, Novák O, Escamez S, Strnad M, Tuominen H and Bellini C (2020) ETHYLENE RESPONSE FACTOR 115 integrates jasmonate and cytokinin signaling machineries to repress adventitious rooting in Arabidopsis. BioRxiv 12.27.886796 - https://doi.org/10.1101/2019.12.27.886796
  • Brunoni F, Casanova-Sáez R, Šimura J, Karady M, Collani S, Ljung K* and Bellini C* (2020) Conifers exhibit a characteristic inactivation of auxin to maintain tissue homeostasis. New Phytologist. https://doi.org/10.1111/nph.16463
  • Lakehal L, Chaabouni S, Cavel E, Le Hir R, Ranjan A, Raneshan Z, Novak O, Pacurar DI, Perrone I, Jobert F, Gutierrez L, Bako L, Bellini C (2019) A molecular framework for TIR1/AFB-Aux/IAA-dependent auxin sensing controlling adventitious rooting in Arabidopsis. Molecular Plant 12 (11), 1499-1514. https://doi.org/10.1016/j.molp.2019.09.001
  • Aubry E, Dinant S, Vilaine F, Bellini C and Le Hir R (2019) Lateral transport of organic and inorganic solutes. Plants 8, 20, https://doi.org/10.3390/plants8010020.
  • Dinant S, De Marco F, Wolff N, Vilaine F, Gissot L, Aubry E, Sandt C, Bellini C and Le Hir R (2019) Synchrotron FTIR and Raman spectroscopy provide unique spectral fingerprints for Arabidopsis floral stem vascular tissues. Journal of Experimental Botany 70:871-884. https://doi.org/10.1093/jxb/ery396
  • Le Hir R, Spinner L, Klemens PAW, Chakraborti D, De Marco F, Vilaine F, Wolff N, Lemoine R, Porcheron B, Géry C, Téoulé E, Chabout S, Mouille G, Neuhaus HE, Dinant S and Bellini C (2015) Disruption of the sugar transporters AtSWEET11 and AtSWEET12 affects vascular developments and freezing tolerance in Arabidopsis. Molecular Plant 8:1687-1690. https://doi.org/10.1016/j.molp.2015.08.007

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