ISSN 1021-4437, Russian Journal of Plant Physiology, 2006, Vol. 53, No. 3, pp. 310–315. © MAIK “Nauka /Interperiodica” (Russia), 2006.
Published in Russian in Fiziologiya Rastenii, 2006, Vol. 53, No. 3, pp. 348–353.
Stomata regulate gas exchange through the aerial
plant epidermis by controlling the width of a pore bor-
dered by two guard cells [1–5] and thus play a crucial
role in productivity and survival of terrestrial plants.
The stomata distribution pattern in the leaf epidermis is
not only genetically controlled, but also affected by
environmental factors such as light intensity, humidity,
temperature, atmospheric carbon dioxide level, soil
moisture, and nutrient availability, and by the internal
architecture and leaf position [6–10].
Stomata are usually scattered in the leaf epidermis
and separated from one another by a stomata-free
region preventing direct contact between the stomata
[11–13]. The production of epidermal cells (ECs) from
the meristemoid apparently ensures that mature sto-
mata are not in contact with one another in wild-type
plants [1, 14]. However, in some vascular plant species
that are conﬁned to only a few genera, stomata are not
distributed randomly scattered in leaf epidermis, but
rather are arranged adjacently to form stomatal clusters.
A stomatal cluster is termed as a group of two or more
stomata that make direct contact [15, 16]. Stomatal
clusters have been observed only in 38 genera of
19 vascular plant families, including
(Crassulaceae) . The ﬁrst sto-
matal cluster mutation reported was
L.), which had double or tri-
ple stomata complexes in several organs with wax deﬁ-
ciency . Treated with ethyl methanesulfonate
(EMS), mutants such as
too many mouths
stomatal density and distri-
), which all had stomatal clusters were iso-
lated from plants of
[1, 18, 19]. The mature structure of singly occurring
stomata and the process of their development has been
widely reported [20, 21]. Comparative studies of the
initiation, differentiation, and development of the clus-
tered stomata in the mutants and the singly occurring
stomata in the wild-type plants of
light on the role of the relevant genes in controlling ini-
tiation of the precursor cells and determining the distri-
bution of stomata [14, 19, 22–24]. However, little is
known about the development process and mechanism
of stomatal clusters and their distribution patterns in
naturally occurring vascular plants.
, an East Asian endemic plant, has a
few stomatal clusters, as well as singly occurring sto-
mata on its leaves. This study focuses on the develop-
mental mechanism and distribution pattern of the sto-
matal clusters in
by tracing the stomata
origin and quantifying the distribution pattern over the
abaxial surface of the whole leaves.
Developmental Mechanism and Distribution Pattern of Stomatal
X. Zhao, X. Dai, G. Wang, Z. Shen, H. Zhang, and M. Qiu
Agroecology Institute, College of Life Sciences, Zhejiang University, Hangzhou, 310029, China;
Received October 11, 2005
—We report the stomatal cluster development mechanism and distribution pattern in
The results indicated that the clustered arrangement of meristemoids at the juvenile stage of the leaf
development contributed greatly to the pattern of stomatal clusters. Additionally, division of an epidermal cell
(EC), which is between small stomata, and growth of small stomata to push the ECs aside to become directly
contacting had an impact on the development as well as the pattern of stomatal clusters. The latter way may
play a more important role in stomata clustering of the wide-type
There are no signiﬁcant differ-
ence in the stomatal index (the number of stomata per the sum of the number of epidermal cells and the number
of stomata) among different part of leaves, while the stomatal cluster index (the number of stomata in stomatal
clusters per the total number of stomata) was found to increase gradually from the apex to the base and from
the middle part to the marginal part of the leaf. The possible reason of this pattern was discussed.
Key words: Cinnamomum camphora - stomatal cluster - development - distribution pattern
: EC—epidermal cells; FAA—formalin–acetum–
50% alcohol solution, (5 : 5 : 90); GMC—guard mother cell;
MCs—meristemoid cells; MMCs—meristemoid mother cells;
SI—stomatal index; SCI—stomatal clustering index.
The text was submitted by the authors in English.