Zheng Lab: Nutrient Balance Signaling
Networks in Plants
PI: Zhi-Liang Zheng (PhD, 1999, Ohio State University)
Associate Professor
Department of Biological
Sciences
Lehman College, City University of New York
250 Bedford Park Blvd. West
Bronx, NY 10468
Graduate School and University Center
365 Fifth Ave.
New York, NY 10016
Office: 2401 Science Hall
Lab: 2404 Science Hall
(718) 960-6955 (Office)
Too
drought-stressed to sustain …? Enjoy the
Grand Canyon in all its majesty! (Dr. Z-L Zheng, Summer 2003)
(718)
960-5741 (Lab)
(718) 960-8236
(Fax)
E-mail: zhiliang.zheng@lehman.cuny.edu
Teaching
BIO
238 Genetics (undergraduate
level, 4 credits: 2-hr lecture, 4-hr
lab)
BIO
501 Special
Topics in Genetics (graduate
level, 4 credits: 4-hr lecture)
Research
Plants are non-motile, photoautotrophic organisms and
therefore they must respond and adapt to the constantly changing environments
(such as light, temperature, water, CO2 and nutrients). Nutrient
availability is one of the most critical factors that limit plant growth and
crop yield. Because of the lack of knowledge that governs how much and when
mineral nutrients should be applied to crops, farmers tend to apply excessive
amounts of fertilizers, which in turn negatively impacts ecosystems and
environments. Therefore, in order to improve the nutrient use efficiency and
optimize the application of fertilizers, it is critical to dissect the fine-tuned
but complex nutrient perception and signal transduction networks. Our research
is currently focused on the major nutrients such as carbon (C), nitrogen (N)
and sulfur (S), with the following specific aims:
OSU1-mediated C/N balance signaling Cellular C and N metabolism
must be tightly coordinated to sustain optimal plant growth and development at
the molecular and whole plant systems levels (Figure 1).
Furthermore, C/N balance is also critical for the ecosystem response to
elevated atmospheric CO2. Despite numerous physiological and molecular studies
in C/N balance or ratio response, very few genes have been shown to play
important roles in C/N balance signaling.
Using a genetic approach, we recently identified a novel
gene (OVERSENSITIVE TO SUGAR1)
involved in C/N balance response in Arabidopsis
thaliana (Gao et al., 2008). Mutations in the OSU1 gene result in the hypersensitivity of the seedlings to the
imbalanced C/N (high C/low N, and low C/high N), but the osu1 mutants respond normally as wild-type under the balanced C/N,
low C/low N and high C/high N (Figure 2).
OSU1 encodes a putative
AdoMet-dependent methyltransferase. Interestingly, osu1 mutants are allelic to qua2/tsd2, the cell-adhesion-defective
mutants reported by two other groups (Mouille et al., 2007; Krupkova et al.,
2007). This indicates that OSU1/QUA2/TSD2 might either have distinct substrates
in the control of cell adhesion and C/N balance response or is important in
linking cell wall biogenesis and C/N balance response. We are currently
investigating its signaling mechanisms in the C and N nutrient balance
response.
Novel components in C-N-S cross-talk Through a C, N and S combinatorial design (Figure 3), we have revealed that activation of a vacuolar sulphate
transporter gene (SULTR4;2) and a
putative thioglucosidase gene by sulfur (S) deficiency is primarily dependent
on the C availability which interacts synergistically with N (Dan et al.,
2007). This demonstrates the differential effects of C, N and S nutrients on
gene expression. To understand the regulatory mechanism, we have taken
advantage of this novel nutrient regulatory pattern to identify nutrient
sensing/signaling proteins involved in the C-N-S cross-talk. Genetic,
physiological and molecular approaches will be used to understand how plants
sense the nutrient status and cross-talk to optimize the opportunity for
cellular metabolism, growth and development.
Role of hormones in nutrient signaling Plant
hormones play an important role in modulating intracellular and intercellular
responses to both internal and external nutrient status. We have shown that
auxin, the key hormone in plants, plays a negative regulatory role in part of
sulphate deficiency response (Dan et al., 2007). Furthermore, abscisic acid (ABA
Control of cytoskeletal
organization in root hair-mediated nutrient uptake and response Root
hairs are important for both the anchorage of the root system to the soil and
the uptake of water and nutrients, although they are not essential for plant
growth and development. Root hairs are long, thin tubular-shaped outgrowths
from root epidermal cells called trichoblasts. Root hair tip growth is one of
the few extreme types of highly dynamic, polarized growth, and has been used as
a unique model system for the study of plant cell polarity. This dynamic process
requires the well-coordinated cytoskeletons, such as actin filaments (AF) and
microtubules (MT), to facilitate active organelle and vesicle transport.
Constitutive activation of ROP2 and other members of ROP GTPases have been
shown to disrupt the root hair tip growth, likely as a result of the alteration
in AF and MT organizations. Interestingly, the tip growth defect caused by the
constitutive activation of ROP2 can be enhanced by increasing concentrations of
C (Figure 4), indicating a link
between the cytoskeletal organization and nutrient response. To identify novel
components of the ROP2-regulated MT and AF cross-talk, we have used a forward
genetic approach, together with cell biological and biochemical tools, to
understand how ROP2 and a kinesin called MRH2 act to control the MT
organization and coordinate with AF (Yang et al., 2007).
Publications
Zheng Z-L (2009) Carbon
and nitrogen nutrient balance signaling in plants. Plant Signaling & Behavior 4: 584-591
Xin Z, Wang A, Yang
G, Gao P and Zheng Z-L (2009) The Arabidopsis
A4 subfamily of lectin receptor kinases negatively regulates abscisic acid response
in seed germination. Plant Physiology 149: 434-444
Gao P, Xin Z and Zheng Z-L (2008) The OSU1/QUA2/TSD2-encoded
putative methyltransferase is a critical modulator of carbon and nitrogen
nutrient balance response in Arabidopsis.
PLoS ONE 3: e1387
Yang G,
Gao P, Zhang H, Huang S and Zheng Z-L (2007) A mutation in MRH2 kinesin enhances
the root hair tip growth defect caused by constitutively activated ROP2 GTPase
in Arabidopsis. PLoS ONE 2: e1074
Dan H, Yang G and
Zheng Z-L (2007) A negative regulatory role for auxin in sulphate deficiency
response in Arabidopsis thaliana. Plant Molecular Biology 63: 221-235
Xin Z, Zhao Y and
Zheng Z-L (2005) Transcriptome analysis reveals specific modulation of abscisic
acid signaling by ROP10 small GTPase in Arabidopsis. Plant Physiology 139: 1350-1365
Fu Y, Gu Y, Zheng
Z-L, Wasteneys G and Yang Z (2005) Arabidopsis interdigitating cell growth
requires two antagonistic pathways with opposing action on cell morphogenesis. Cell 120: 687-700
Zheng Z-L, Nafisi M,
Tam A, Li H, Crowell DN, Chary SN, Shen J, Schroeder JI and Yang Z (2002)
Plasma membrane-associated ROP10 small GTPase is a specific negative regulator
of abscisic acid responses in Arabidopsis. Plant Cell 14: 2787-2797
Li H, Shen J, Zheng
Z-L, Lin Y and Yang Z (2001) The Rop GTPase switch controls multiple
developmental processes in Arabidopsis. Plant Physiology 126: 670-684
Zheng Z-L, Yang Z, Jang J-C and Metzger JD (2001) Modification of plant
architecture in chrysanthemum by ectopic expression of the tobacco phytochrome
B1 gene. Journal
of the American Society for Horticultural Sciences 126: 19-26 (Won the American Society for
Horticultural Sciences Most Outstanding Publication Award of 2001)
Zheng Z-L and Yang Z (2000) The Rop GTPase switch turns on polar growth
in pollen. Trends in Plant
Sciences 5: 298-303
Zheng Z-L and Yang Z
(2000) The Rop GTPase: an emerging signaling switch in plants. Plant Molecular Biology 44: 1-9