Identiﬁcation and characterization of NARROW AND ROLLED
LEAF 1, a novel gene regulating leaf morphology and plant
architecture in rice
Received: 28 August 2009 / Accepted: 30 January 2010 / Published online: 13 February 2010
Ó Springer Science+Business Media B.V. 2010
Abstract Leaf morphology is an important agronomic
trait in rice breeding. We isolated three allelic mutants of
NARROW AND ROLLED LEAF 1 (nrl1) which showed
phenotypes of reduced leaf width and semi-rolled leaves
and different degrees of dwarﬁsm. Microscopic analysis
indicated that the nrl1-1 mutant had fewer longitudinal
veins and smaller adaxial bulliform cells compared with
the wild-type. The NRL1 gene was mapped to the chro-
mosome 12 and encodes the cellulose synthase-like protein
D4 (OsCslD4). Sequence analyses revealed single base
substitutions in the three allelic mutants. Genetic comple-
mentation and over-expression of the OsCslD4 gene con-
ﬁrmed the identity of NRL1. The gene was expressed in all
tested organs of rice at the heading stage and expression
level was higher in vigorously growing organs, such as
roots, sheaths and panicles than in elsewhere. In the mutant
leaves, however, the expression level was lower than that
in the wild-type. We conclude that OsCslD4 encoded
by NRL1 plays a critical role in leaf morphogenesis and
vegetative development in rice.
Keywords NARROW AND ROLLED LEAF 1 Á
CslD4 Á Map-based cloning Á Rice (Oryza sativa L.)
Plant leaves and all other lateral organs are derived from
founder cells of the peripheral zone in the shoot apical
meristem (SAM). The founder cells differentiate into leaf
primordia and consequently develop into ﬂat leaves after
differentiation along the adaxial-abaxial, proximodistal
and mediolateral axes (Scanlon 2000; Tsiantis 2001;
Bowman et al. 2002). The establishment of these axes is
essential for leaf morphogenesis. Mutants with abnormal
leaf development associated with irregular polarity have
been isolated, which show narrow, rolling (curling),
needle-like, thread-like or radical leaf lamina (Waites and
Hudson 1995; Scanlon et al. 1996; Timmermans et al.
1998; Telfer and Poethig 1998; McConnell and Barton
1998; Nelson et al. 2002; Juarez et al. 2004; Yu et al.
2005; Yan et al. 2008).
In rice, mutants with narrow or rolled leaves such
as nal1-nal6 and rl1-rl6 have been identiﬁed and mapped
with morphological markers (http://www.shigen.nig.ac.
jp/rice/oryzabase/top/top.jsp). Recently, mutants of the
OsAGO7 gene encoding an Argonaute (AGO) family
member have been shown to cause upward curling of
leaves in rice. Phylogenetic analysis indicated that OsAG-
O7 is an ortholog of Arabidopsis ZIPPY (
which contains PAZ and PIWI domains (Shi et al. 2007).
The NARROW LEAF 7 (CONSTITUTIVELY WILTED 1)
gene encodes an auxin biosynthesis enzyme that belongs to
the YUCCA family (Woo et al. 2007; Fujino et al. 2007).
The SHALLOT-LIKE1 (ROLLED LEAF 9) gene encodes a
SHAQKYF class MYB family transcription factor, and its
mutants have vascular bundles to appear on the abaxial side
of the leaf lamina (Yan et al. 2008; Zhang et al. 2009a, b).
Similarly, a mutation in NARROW LEAF 1, encoding a
plant speciﬁc protein associated with polar auxin transport,
Jiang Hu and Li Zhu have contributed equally to this work.
J. Hu Á L. Zhu Á D. Zeng Á Z. Gao Á L. Guo Á Y. Fang Á
G. Zhang Á G. Dong Á M. Yan Á J. Liu Á Q. Qian (&)
State Key Laboratory of Rice Biology, China National Rice
Research Institute, Chinese Academy of Agricultural Sciences,
359 Tiyuchang Road, 310006 Hangzhou, China
Plant Mol Biol (2010) 73:283–292