Department of Plant Sciences

Dr Julia Davies, Senior Lecturer

Ion Transport

The Science we do

The Transport Group primarily studies the plasma membrane (PM) Ca²⁺ channels involved in root signal transduction, nutrition and growth. Following the first characterisation of a PM Ca²⁺ channel involved in root hair growth (Véry and Davies, 2000), the group has gone on to identify distinct types of Ca²⁺-permeable channels in the PM of Arabidopsis root epidermis, including one that could deliver toxic levels of Na⁺ into roots (Demidchik et al., 2002, 2003. We have also defined salt stress-induced changes in epidermal PM conductance (Shabala et al., 2006). We have shown that root hair and epidermal PM harbours Ca²⁺ channels that are differentially regulated by voltage, permitting flexibility of Ca²⁺ uptake (Miedema et al., 2001; Demidchik et al., 2002). The first characterisation of a plant Ca²⁺-permeable channel activated by hydroxyl radicals (Demidchik et al., 2003) lead to the discovery that these channels operate downstream of a PM NADPH oxidase (AtRBOHC) in root and root hair growth (Foreman et al., 2003). Since this first demonstration of NADPH oxidase involvement in development, we have shown that AtRBOHC governs hypoosmotic stress response and wall strength (Macpherson et al., 2008) Epidermal cell development changes the sensitivity of Ca²⁺ channels to H₂O₂ and activation is vectorial (Demidchik et al., 2007), revealing the complexity of the relationship between channels and reactive oxygen species (ROS) that is relevant to stress, immunity and growth.

We identified extracellular ATP (eATP) and eADP as novel upstream regulators of plant PM Ca²⁺ channels and [Ca²⁺]_cyt (Demidchik et al., 2003, 2009. Groups worldwide are now investigating the mechanisms, consequences and applications of eATP signalling such as food preservation. We have established that plant annexins form Ca²⁺-permeable channels in vitro (Laohavisit et al., 2009). We have also shown that maize annexins form Ca²⁺ channels in bilayers containing malondialdehyde, a typical product of membrane peroxidation (Laohavisit et al., 2010). Work on annexins as calcium-permeable channels is ongoing in the group.

The group has benefited from several national and international collaborations. Funding has come principally from the BBSRC, the Leverhulme Trust, the Royal Society, the Newton Trust and the Brooks Fund. We thank everyone who has helped us.

Joining the Group

Prospective graduate students with a clear and demonstrable interest in ion transport are asked to check their eligibility against the criteria provided by the Life Sciences Graduate School. Overseas students are advised that a GPA of over 3.8 is now the norm to be competitive for funding. The Group takes one summer student a year so early application is advisable.

Facilities

The Transport Group benefits from newly refurbished laboratory and office accommodation, shared with the Signal Transduction Group. There is a main lab with bench space for 16, a data analysis room, four dedicated electrophysiology/imaging rooms and a dark lab for circadian studies.

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PhD Projects available

Contact us:

Department of Plant Sciences
University of Cambridge
Downing Site Downing Street
CAMBRIDGE CB2 3EA
Email: jmd32@cam.ac.uk
Office +44 (0)1223 333900
Lab +44 (0)1223 748980

Using laser microsurgery to cut the root hair cell wall we can release specific parts of the cell for electrophysiological studies.