Alisdir R. Fernie talks with
ScienceWatch.com and answers a few questions about
this month's Fast Moving Front in the field of Plant &
Article: Metabolic profiling of transgenic tomato
plants overexpressing hexokinase reveals that the influence
of hexose phosphorylation diminishes during fruit
Authors: Roessner-Tunali, U;Hegemann, B;Lytovchenko,
A;Carrari, F;Bruedigam, C;Granot,
Journal: PLANT PHYSIOL, 133 (1): 84-99 SEP 2003
Addresses: Max Planck Inst Mol Pflanzenphysiol, Dept Lothar
Willmitzer, Muhlenberg 1, D-14476 Golm, Germany.
Max Planck Inst Mol Pflanzenphysiol, Dept Lothar
Willmitzer, D-14476 Golm, Germany.
Agr Res Org, Volcani Ctr, Inst Field & Garden Crops,
IL-50250 Bet Dagan, Israel.
Why do you think your paper is highly
This is probably due to a couple of factors—it addressed the hot
topic of sugar sensing but also was one of the first papers describing
metabolic profiling in the tomato. The second factor is probably more
crucial in terms of collected citations.
Does it describe a new discovery, methodology, or
synthesis of knowledge?
Ours is largely a new methodology, but the approach we used, which took
into account developmental changes in metabolism, also represents a large
synthesis of knowledge.
Would you summarize the significance of your paper
in layman's terms?
"...it addressed the
hot topic of sugar sensing
but also was one of the first
papers describing metabolic
profiling in the
The importance of a specific reaction step in the initial pathway of
non-photosynthetic energy metabolism was investigated during the fruit
ripening process. The approach taken was to analyze genetic variants of
tomato expressing different levels of the enzyme responsible for catalyzing
the first chemical conversion of the pathway.
Fruit and leaf material was harvested at different developmental stages and
its chemical composition analyzed by gas chromatography-mass spectrometry
(GC-MS). The results of these studies revealed that the importance of this
particular enzyme declines throughout the ripening process.
How did you become involved in this research and
were there any particular problems encountered along the way?
The research was prompted by the initial description of these tomatoes by
the group of David Granot at the Volcani Institute in Israel. When I
initiated the project I was a post-doc in the laboratory of Lothar
Willmitzer working on sugar sensing in potatoes. Frustratingly, genetic
variants of potato, altered in their hexokinase activities, did not display
such dramatic phenotypic differences. Switching to tomato was therefore an
easy decision to make.
Where do you see your research leading in the
We have in recent years applied this metabolite profiling method, as well
as others that have been subsequently developed, in quantitative trait
loci studies which harness wide genetic variance abundant in tomato
and its wild relatives. In taking this approach we have been able to
identify a number of genomic regions of high importance for the
determination of chemical composition of the fruit at harvesting.
Coupling this profiling to that of standard agronomic traits allows us to
identify lines which have elevated metabolite content without major
morphological changes, thus circumventing the common problem of yield
penalties which are often associated with metabolic engineering strategies.
Do you foresee any social or political implications
for your research?
The follow-up work has high potential for use in breeding strategies,
particularly among those intent on producing healthier and more nutritious
Alisdir R. Fernie
Department of Molecular Physiology
Max-Planck-Institute for Molecular Plant Physiology
Keywords: metabolic profiling, transgenic tomato
plants, hexokinase activities, hexose phosphorylation, genetic variance,
sugar sensing, gas chromatography-mass spectrometry, non-photosynthetic
energy metabolism, agronomic traits, elevated metabolite content.