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Halophytes: what makes them special? Revealing ionic mechanisms of salinity tolerance
Citation
Shabala, SN and Moreno, AR and Hariadi, YC and Mackay, AS and Tian, Y and Bose, J, Halophytes: what makes them special? Revealing ionic mechanisms of salinity tolerance, Proceedings of the XVIII International Botanical Congress, 24-20 July 2011, Melbourne, Victoria, pp. Sym030. (2011) [Conference Extract]
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Abstract
The increasing problem of global land salinisation and
associated multibillion dollars losses in crop production
require a better understanding of key physiological
mechanisms conferring salinity tolerance in crops. The
effective way of gaining such knowledge comes from
studying halophytes. Halophytes have always attracted
the attention of plant physiologists, due to their
remarkable ability to tolerate and even benefit from salt
concentrations that kill most other plant species. At the
very least, halophytes may provide genes that allow
transgenic conference of salinity tolerance to crops. In
addition, some halophytes have already been tested as
vegetable, forage and oilseed crops in agronomic field
trials, whilst others show good potential to be developed
as crops. Surprisingly, our knowledge of fundamental
ionic and molecular mechanisms conferring salinity
tolerance in halophytes is rather limited, and at best is
restricted to several model species. This talk summarises
the current knowledge of physiological mechanisms
regulating ion uptake and sequestration in halophytes and
provides insights into the identity of membrane-transport
systems mediating ion transport in halophyte root and
leaf tissues. The focus of this study was on two species:
quinoa (Chenopodium quinoa Willd.) and Atriplex
(Atriplex lentiformis L.). A range of physiological
techniques (leaf gas exchange and photosynthetic
characteristics; sap osmolality; tissue elemental
composition) were used to reveal mechanisms of osmotic
adjustment and tissue-specific ion compartmentation in
both species at the whole-plant level. It was found that
95% of osmotic adjustment in old leaves and between 80
and 85% of osmotic adjustment in young leaves was
achieved by means of accumulation of inorganic ions
(Na+, K+ and Cl-) when plants were grown at elevated (up
to 500 mM NaCl) salinity levels, whilst the role of
organic osmolytes was very limited. Both species also
possessed an efficient mechanism to control Na+ and K+
loading into the xylem, as well as for efficient Na+
sequestration in leaves. Whole-plant experiments were
complemented by a range of microelectrode studies (noninvasive
ion flux measurements; membrane potential;
patch clamp) aimed to reveal the identity of specific ion
transporters mediating the above process. We compare
the kinetics of net K+ and Na+ fluxes between different
root zones (e.g. elongation vs mature zone) and report a
differential sensitivity of quinoa and Atriplex root tissues
to NaCl and oxidative (hydroxyl-generating Cu/ascorbate
mixture) stress. We show that regulation of both
depolarization-activated outward-rectifying K+-selective
(GORK) channels and non-selective cation (NSCC)
channels are instrumental to halophytes adaptation to
saline conditions, and reveal an important role for a H+-
ATPase pump in this regulation. We also demonstrate a
feasibility of using the MIFE technique to map ion flux
profiles from intact plant leaves and report, for the first
time, in situ data on patterns of net K+, Na+ and H+ flux
kinetics from halophyte bladders in response to a range
of salinity treatments.
Item Details
Item Type: | Conference Extract |
---|---|
Research Division: | Biological Sciences |
Research Group: | Plant biology |
Research Field: | Plant physiology |
Objective Division: | Expanding Knowledge |
Objective Group: | Expanding knowledge |
Objective Field: | Expanding knowledge in the agricultural, food and veterinary sciences |
UTAS Author: | Shabala, SN (Professor Sergey Shabala) |
UTAS Author: | Hariadi, YC (Mr Yuda Hariadi) |
UTAS Author: | Mackay, AS (Mr Alexander Mackay) |
UTAS Author: | Bose, J (Dr Jayakumar Bose) |
ID Code: | 84820 |
Year Published: | 2011 |
Deposited By: | Agricultural Science |
Deposited On: | 2013-06-03 |
Last Modified: | 2013-10-08 |
Downloads: | 16 View Download Statistics |
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