RNAi knockdown of Oryza sativa root meander curling
gene led to altered root development and coiling which
were mediated by jasmonic acid signalling in rice
*, JUNHUA LI
*, YUNYUAN XU
, YE HAN
, YUE BAI
, GUOXIN ZHOU
, YONGGEN LOU
, & KANG CHONG
Research Center for Molecular Developmental Biology, Key Laboratory of Photosynthesis and Environmental Molecular
Physiology, Institute of Botany, the Chinese Academy of Sciences, Beijing 100093,
National Centre for Plant Gene Research,
Graduate School of the Chinese Academy of Sciences, Beijing 100049 and
Institute of Applied Entomology,
Zhejiang University, Hangzhou, 310029, China
Jasmonic acid (JA) is a well-known defence hormone, but
its biological function and mechanism in rice root develop-
ment are less understood. Here, we describe a JA-induced
putative receptor-like protein (OsRLK, AAL87185) func-
tioning in root development in rice. RNA in situ hybridiza-
tion revealed that the gene was expressed largely in roots,
and a fusion protein showed its localization on the plasma
membrane. The primary roots in RNAi transgenic rice
plants meandered and curled more easily than wild-type
(WT) roots under JA treatment. Thus, this gene was
renamed Oryza sativa root meander curling (OsRMC).
The transgenic primary roots were shorter, the number of
adventitious roots increased and the number of lateral roots
decreased as compared to the WT. As well, the second
sheath was reduced in length. Growth of both primary roots
and second sheaths was sensitive to JA treatment. No sig-
niﬁcant change of JA level appeared in the roots between
the transgenic rice line and WT. Expression of RSOsPR10,
involved in the JA signalling pathway, was induced in trans-
genic rice. Western blotting revealed OsRMC induced by
JA. Our results suggest that OsRMC of the DUF26 sub-
family involved in JA signal transduction mediates root
development and negatively regulates root curling in rice.
Key-words: DUF26; RSOsPR10; OsOPR.
Jasmonic acid (JA) plays an essential role in the plant
defence response, but is also relevant to plant growth and
development for seed germination, senescence, fruit devel-
opment, root growth, pollen gestation, bulb formation and
tendril coiling (Browse 2005). Physiology assays in rice
showed that JA can reduce elongation of primary roots and
second sheaths (Yamane et al. 1981; Moons et al. 1997), and
low concentrations can induce the formation of adventi-
tious roots (Moons et al. 1997) and lateral roots (Wang et al.
2002). However, little is known about JA’s role and its
mechanism in rice root development.
Receptor protein kinases play important functions in sig-
nalling processes regulating growth and development, such
as disease resistance, perceiving hormone signal transduc-
tion and response to internal and external cues (Torii 2000).
The receptor kinases have been grouped into 15 subfamilies
on the basis of extracellular domains (Shiu & Bleecker
2001, 2003). One of these subfamilies is the domain
unknown function 26 (DUF26) [cysteine-rich repeat
(CRR)] family. Several genes of the DUF26 family from
Arabidopsis were induced by pathogen infection, reactive
oxygen species and salicylic acid (Czernic et al. 1999; Du &
Chen 2000; Ohtake, Takahashi & Komeda 2000). These
studies revealed that at least some of the CRR protein
subfamily genes are involved in plant perception and
response to biotic and/or abiotic stress signalling, including
JA signal transduction. But less is known about the biologi-
cal function of the CRR proteins.
Here, we used a reverse genetics approach to study the
functions of a JA-induced DUF26 protein in rice root devel-
opment. The gene was designated Oryza sativa root
meander curling (OsRMC), because RNAi transgenic
plants showed a phenotype of root meander curling on
germination. On the basis of its response to JA, OsRMC
could be a negative regulator in JA signalling.
MATERIALS AND METHODS
OsRMC isolation and vector construction
Experiments of RNA extraction from young roots
in rice, RT–PCR, were as described previously (Jiang et al.
2006). The open reading frame (ORF) of OsRMC
(AAL87185) was ampliﬁed with a pair of primers:
5′-cgggatccatggcgcggtgcactttg-3′ containing a BamH I re-
striction site (underlined) and 5′-cggaattcctactcacgcagca
ccacc-3′ containing an EcoR I restriction site (underlined).
The products digested with BamH I and EcoR I were
Correspondence: K. Chong. Fax: 86 10 8 259 4821; e-mail:
*Equal contributors to this work.
Plant, Cell and Environment (2007) 30, 690–699 doi: 10.1111/j.1365-3040.2007.01663.x
© 2007 The Authors
Journal compilation © 2007 Blackwell Publishing Ltd690