ISSN 10214437, Russian Journal of Plant Physiology, 2011, Vol. 58, No. 5, pp. 851–863. © Pleiades Publishing, Ltd., 2011.
Root system architecture is a key determinant of
nutrient and water use efficiency in crops. Root archi
tecture depends on the integration of genetic programs
governing root growth patterns and environmental
factors . Plants employ significant developmental
plasticity to respond to environmental changes. Abi
otic stressinduced root morphogenic responses were
observed in many studies with diverse plant species .
For example, the modifications of the root system
caused by excess copper, paraquat, salicylic acid,
This text was submitted by the authors in English.
These authors contributed equally to this work.
NaCl, and Cd were reported in
Regulation of the root system growth is a complex
process involving plant hormones, cell cycle, and
reactive oxygen species (ROS). Auxin, one of the most
important phytohormones, plays a crucial role in the
modulation of the root architecture. Aluminum
caused inhibition of root growth was shown to result
from the altered auxin distribution in roots . The
changes of the root system in salinestressed plants
were shown to be related to auxin redistribution .
The cadmiuminduced changes in auxin distribution
correlated well with lateral root formation in
. There is evidence that cell cycle regulation
also plays a vital role in growth responses to unfavor
able conditions. In
roots, changes in the
cell cycle machinery were accompanied by a decreased
Superoxide Radical and Auxin Are Implicated in Redistribution
of Root Growth and the Expression of Auxin and CellCycle Genes
in CadmiumStressed Rice
F. Y. Zhao
, F. Hu
, M. M. Han
, S. Y. Zhang
, and W. Liu
College of Life Sciences, Shandong University of Technology, Zibo 255049, Shandong Province, P.R. China
Shandong Rice Research Institute, Jining 272077, Shandong Province, P.R. China
Received August 18, 2010
—Changes of root growth and the expression of auxin and cellcycle genes were analyzed in rice
L. cv. Zhonghua No. 11) treated with Cd alone, Cd plus TIBA (2,3,5triiodobenzoic acid, an
inhibitor of polar auxin transport) or IBA (indole3butytric acid) and Cd plus Tiron (a scavenger of
or DDC (sodium diethyldithiocarbamate, a superoxide dismutase inhibitor). It was shown that Cdstimu
lated rice root growth can be further enhanced by Cd plus IBA or DDC treatments but can be significantly
suppressed following Cd together with Tiron or TIBA application. A comprehensive expression analysis of
auxin genes, such as
(auxin response factors), and core cellcycle
genes, such as
s in differently treated roots was conducted by semiquantitative RTPCR. The
results showed that the expressions of 21 out of 35 tested auxin genes and 51 out of 63 tested cellcycle genes
were regulated by various treatments. Among the modified expression profiles of 72 genes, 53 and 59 genes
were up or downregulated by auxin (including Cd plus TIBA or IBA treatments) and (including Cd
plus Tiron or DDC treatments), respectively. In the roots treated with Cd plus IBA or TIBA, the expressions
of 39 genes changed differently from those under single Cd treated roots. Following Cd plus DDC or Tiron
treatment, the transcripts of 36 genes were also altered differently from those under single Cd treatment.
Obviously, auxin and affected the expression of auxin and core cellcycle genes under Cd stress. Taken
together, our results indicated that in Cdstressed rice plants, and auxin were implicated in the redistri
bution of root growth and the expression of auxin and cellcycle genes.
, auxin, cadmium stress, cell cycle, root architecture, superoxide radical.
: DDC—sodium diethyldithiocarbamate; IBA—
indole3butytric acid; RTPCR—semiquantitative reverse
transcriptionPCR; TIBA—2,3,5triiodobenzoic acid.