© Benaki Phytopathological Institute
Hellenic Plant Protection Journal
9:
16-27, 2016
DOI 10.1515/hppj-2016-0002
Laboratory of General and Agricultural Microbiology,
Department of Crop Science, Agricultural University
of Athens, Iera Odos 75, Votanikos, GR-118 55 Athens,
Greece
* Corresponding authors:
ponent of this process. Bacterial motility has
been classified into discrete types, based on
structural
surface appendages or internal struc-
tures
involved, and bacterial species may em-
ploy more than one type for translocation
and colonization (Jarrell and McBride, 2008).
Most bacteria are able to swim in aquatic en-
vironments powered by rotating flagella.
This type of motility is referred as swimming
motility. However, a range of different mech-
anisms have evolved that facilitate move-
ment and spreading on a variety of surfaces
(Jarrell and McBride, 2008). Swimming mo-
tility is considered to be an individual bac-
terial behavior (Jarrell and McBride, 2008;
Harshey, 2003; Kearns, 2010). Surface move-
ment can depend on the presence of flagella
(i.e., swarming), the extension and retraction
of type IV pili (i.e., twitching motility), the in-
volvement of rearrangements in the shape
of the cell that generate standing waves, the
secretion of material from the poles, and lo-
calized focal adhesion complexes between
cells and the substrate (i.e., gliding), or “pas-
sive” surface translocation where the expan-
sive force of cell proliferation moves cells at
the periphery of a cell mass (i.e., sliding).
Swarming is a multicellular movement
of flagellated bacteria over solid surfaces
and this trait is displayed by dozens of bac-
terial species under laboratory conditions.
REVIEW ARTICLE
Swarming motility in plant-associated bacteria
A. Venieraki*, P.Ch. Tsalgatidou, D.G. Georgakopoulos, M. Dimou and P. Katinakis*
Summary
Plant-associated environments harbor a huge number of diverse bacteria that compete
and/or cooperate for the occupation of the most nutrient-rich ecological niches. Motility, a common
trait among bacteria, has long been assumed to provide a survival advantage to skilful bacteria in in-
vading these environments. Bacterial surface motility, such as swarming, a flagella-driven type of sur-
face movement, although mostly observed and studied on agar substrates, is emerging as a major trait
involved in many functions of plant-associated bacteria in regard to their ability to colonize and spread
on their host. In this review, we address some novel swarming motility strategies, which enable bacte-
ria to colonize, disperse and compete in plant surfaces.
Additional keywords
: Competition, cooperation, fungi
Introduction
Plants harbor epiphytic or endophytic com-
munities of bacteria that colonize almost
all tissues (roots, leaves, stems, vascular tis-
sues, seeds and fruit). In general, plant-asso-
ciated prokaryotes can be grouped based
on the nature of their interaction with host
into commensal, mutualistic, and pathogen-
ic; mutualistic, when it is beneficial for both
organisms, commensal, when one organism
benefits and the other is not affected and
pathogenic, when only the microbe bene-
fits at the expense of the host or host dam-
age. Mutualistic and commensal bacteria in
association with plants are either so-called
ectophytes or endophytes, if their location
is outside or within plant tissues, respective-
ly (Mentes
et al.
, 2013; Berg
et al.
, 2015).
Bacteria move from one location to an-
other in natural niches and this movement
is referred as motility. Plant colonization is a
complex process and motility of bacteria in
soil and/or on plant surfaces is a basic com-
