Suhua Feng & Xing Wang
Deng talk with ScienceWatch.com and answer a few
questions about this month's Fast Breaking Paper in the
field of Plant & Animal Science.
Article Title: Coordinated regulation of
Arabidopsis thaliana development by light and
SH;Martinez, C;Gusmaroli, G;Wang, Y;Zhou, JL;Wang,
F;Chen, LY;Yu, L;Iglesias-Pedraz, JM;Kircher, S;Schafer,
Year: JAN 24 2008
* Yale Univ, Dept Mol Cellular & Dev Biol, New Haven,
CT 06520 USA.
(addresses have been truncated)
Why do you think your paper is highly
Light and gibberellins (GA) are two important factors regulating multiple
aspects of plant development. It was previously known that both pathways
have crosstalk with each other; however, molecular mechanistic insight was
lacking. The study in our paper defines a novel and important connection
between light and GA signaling. Therefore, it is of interest to both light
and hormone signaling fields.
Does it describe a new discovery, methodology, or
synthesis of knowledge?
This paper describes a new discovery. Briefly, in the absence of GA, GA
pathway negative regulator DELLA proteins bind to PIF3, a bHLH-type
transcription factor, to sequester PIF3 from its target gene promoters.
While in the presence of GA, GA receptors GID1 proteins bind DELLA proteins
to target them for proteasome-mediated proteolysis, and free PIF3 can then
bind to promoters.
Xing Wang Deng
Interestingly, PIF3 is a known phytochrome-interacting protein, which plays
important roles in light-induced seedling development, especially in
controlling hypocotyl length, an important characteristic of
photomorphogenesis. Therefore, our results reveal a signaling cascade,
which involves multiple pairs of protein-protein interaction and
contributes to the concerted regulation of Arabidopsis hypocotyl
growth by light and gibberellins.
Would you summarize the significance of your paper in
Together with a paper by Salomé Prat's group at the Centro Nacional
de Biotecnología in Madrid, entitled "A molecular framework for
light and gibberellin control of cell elongation," from the same issue of
Nature 451: 480-84, January 24, 2008, we provided a most
reasonable and intriguing model in which DELLA proteins, which are nuclear
repressors of plant GA responses, negatively control the activity of a
number of transcription factors by binding with a conserved basic
helix–loop–helix (bHLH) DNA-interacting domain. Therefore, the
binding of these transcription factors to DELLA proteins and to gene
promoters would be mutually exclusive. This would enable DELLA proteins to
regulate a large number of genes, which is consistent with their critical
role in GA-induced gene expression.
How did you become involved in this research, and were
there any problems along the way?
The major focus of the laboratory is on light-induced plant growth. Typical
Arabidopsis seedlings grown in light have short hypocotyl and
opened cotyledons; whereas dark-grown seedlings have long hypocotyl and
closed cotyledons. This phenomenon has been fascinating biologists for
centuries. It has also been known, for a long time, that a plant hormone,
gibberellin (GA), is able to induce elongation of hypocotyl, much like the
opposite of light effect.
One interesting similarity between light and GA signaling is that both
pathways contain proteins that either regulate or are targets of
ubiquitin/proteasome-mediated proteolysis. This prompted us to focus on the
DELLA family of GA signaling repressors, which are known substrates of the
ubiquitin/proteasome system. That is how this project got started. This has
been a huge effort, and many difficulties had to be overcome along the way.
One example, we encountered a lot of problems when trying to produce
specific antibodies against all the DELLA proteins. We ended up using
tagged transgenic lines in most of our experiments.
Where do you see your research leading in the future?
Future research may substantiate whether this is the main mechanism how
DELLA proteins function or is it only one of the many ways in which they
work. Follow-up could place emphasis on identifying more transcription
factors that are targeted by DELLA proteins, further dissecting the
interaction between DELLA proteins and transcription factors, and thereby
characterizing the genes regulated by DELLA-controlled transcription
Do you foresee any social or political implications for your
Such implications are not evident at this time. Nonetheless, it is
worthwhile to mention that all food on earth derives from plants and that
wheat mutants of DELLA, which are shorter, more resistant to wind and rain
damage and have increased grain yield, contributed to the so-called "Green
Revolution." Therefore, understanding the precise mode of action of DELLA
proteins might have social benefits in the long run, especially given the
increasing food shortage problems around the world.
Suhua Feng, Ph.D.
Howard Hughes Medical Institute
Molecular, Cell, and Developmental Biology
University of California, Los Angeles
Los Angeles, CA, USA
Xing Wang Deng, Ph.D.
Daniel C. Eaton Professor of Plant Biology
Department of Molecular, Cell, and Development Biology
New Haven, CT, USA Web |