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Tim Flowers answers a
few questions about this month's fast breaking paper in the field of
Plant & Animal Science.
From
•>>October 2005
Field:
Plant & Animal Science
Article Title: Improving crop salt tolerance
Authors: Flowers, TJ
Journal: J EXP BOT
Volume: 55
Page: 307-319
Year: FEB 2004
* Univ Sussex, Sch Biol Sci, Brighton BN1 9QG, E Sussex, England.
* Univ Sussex, Sch Biol Sci, Brighton BN1 9QG, E Sussex, England.
* Sch Plant Biol, Crawley, WA 6009, Australia.
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 Why
do you think your paper is highly cited?
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“After ten years of research using transgenic plants to alter salt tolerance, the value of this
approach has yet to be established in the field.”
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My review was timely: it highlights the problem of
salinization and suggests criteria by which the success, or
otherwise, of a transgenic solution to the problem of developing
salt-tolerant crops can be evaluated. Salinization of
agricultural land has been a problem since Mesopotamian times,
but over the last two centuries, the clearance of land for
agriculture and reliance on irrigation has increased the extent
of the problem. In spite of recognition of the need to develop
salt-resistant crops, this has proven to be a difficult goal to
achieve. Since 1993, there has been an increase in the ability
to produce transgenic plants, which have been promoted, with
some hyperbole, as a solution to breeding salt-resistant crops.
Does
it describe a new discovery or a new methodology that's useful to
others?
The review culminates in suggestions that may be used to
evaluate the salt-tolerance of transgenic crops: simple
criteria, such as the use of fourth-generation transgenics for
measurement of yield in a field situation.
Could
you summarize the significance of your paper in layman's terms?
Soluble salts are often present in groundwater, or build up
in soils when salt and water are added during irrigation and the
water evaporates. If irrigation adds more water than evaporates,
then this leads to a build-up in the water table, a water table
contaminated with salt. Forest clearance can also lead to a
build-up in the water table, as trees evaporate more water over
a year than, say, a cereal crop. As the number of people in the
world increases, increased food production is required, but this
is jeopardized by the spread of salinized land: virtually all
our crops are sensitive to salt. Plant breeders have found it
very difficult to change the salt tolerance of crops, as
tolerance depends on many different properties of a plant,
controlled by many different genes. In spite of this complexity,
there have been many claims in the recent literature that the
transfer of a single gene or a few genes can change the salt
tolerance of a plant. Evaluation of 68 papers produced between
1993 and early 2003, found that only 19 reported quantitative
estimates of plant growth. About half of all the papers reported
data on experiments conducted under conditions where there was
little or no transpiration: such experiments may provide
insights into components of tolerance, but are not grounds for
claims of enhanced tolerance at the whole plant level. After 10
years of research using transgenic plants to alter salt
tolerance, the value of this
approach has yet to be established in the field.
How
did you become involved in this research?
I first started working on the effects of salinity on plants
over 35 years ago on my return from the USA to the University of
Sussex. I began with the basic question of whether the enzymes
of salt-tolerant plants show similar adaptations to those of the
halophilic bacteria and went on to investigate the physiology of
a salt-tolerant plant and then of a salt-sensitive crop. The
early work led to the publication in 1977 of a still highly
cited review in the Annual Review of Plant Physiology,
while the work on rice led to a methodology for increasing salt
tolerance in rice.
What
are the social or political implications of your research?
Generating salt-resistant crops is part of, but not the whole
of, a solution to maintaining food security as the world’s
human population grows over the next 25 years. Salt-resistant
crops may be of particular importance to the poor as, in
general, poor people farm poor land, if they have any land to
farm at all.
Tim Flowers
Professor in Plant Physiology
School of Life Sciences
University of Sussex
Falmer, Brighton
East Sussex, UK
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ESI Special Topics,
October 2005
Citing URL - http://www.esi-topics.com/fbp/2005/october05-TimFlowers.html
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