The age of lima bean leaves influences the richness and diversity of
the endophytic fungal community, but not the antagonistic effect of
endophytes against Colletotrichum lindemuthianum
Rocío C. L
opez-Gonz
alez
a
, Sergio G
omez-Cornelio
b
, Susana C. De la Rosa-García
c
,
Etzel Garrido
a, 1
, Octavio Oropeza-Mariano
a
, Martin Heil
a
, Laila P. Partida-Martínez
a, *
a
Departamento de Ingeniería Genetica, Centro de Investigaci on y de Estudios Avanzados - Unidad Irapuato, Irapuato 36821, Guanajuato, Mexico
b
El Colegio de la Frontera Sur, Campeche 24500, Campeche, Mexico
c
Divisi on Academica de Ciencias Biol ogicas, Universidad Ju arez Aut onoma de Tabasco, Villahermosa 86000, Tabasco, Mexico
article info
Article history:
Received 5 March 2015
Received in revised form
4 November 2016
Accepted 14 November 2016
Corresponding Editor: Barbara Joan Schulz
Keywords:
Foliar fungal endophytes (FFE)
Leaf age
Diversity
Phaseolus lunatus L.
Anthracnose
Colletotrichum lindemuthianum
Biocontrol agents
abstract
Phaseolus lunatus (lima bean) has been a model organism to understand direct and indirect defenses
against herbivores. We investigated the identity and diversity of endophytic fungi associated with young,
mature and old leaves of lima bean in its natural environment. We recovered 758 isolates that were
identified and classified in 142 fungal species from 66 genera, with Curvularia, Fusarium, Phomopsis,
Alternaria and Colletotrichum being the most abundant and diverse Ascomycota genera. Our data revealed
that species richness and diversity increased with leaf age, this factor being also important for the
structure of the endophytic community. The occurrence patterns of fungal species was highly hetero-
geneous among leaves, and only fourteen species were recovered from all three foliar ages investigated.
In vitro dual assays between endophytes and the plant pathogen Colletotrichum lindemuthianum revealed
that most endophytes tested can inhibit the growth of this pathogen, suggesting their potential as
biocontrol agents.
© 2016 Elsevier Ltd and British Mycological Society. All rights reserved.
1. Introduction
It is now widely recognized that most plants on Earth are
associated with one or more endophytic fungal species (Schulz and
Boyle, 2005; Rodriguez et al., 2009). This group of microorganisms
is characterized by a strikingly high diversity and local heteroge-
neity, complicating the understanding of their ecological role and
the mechanisms supporting their interactions with the host plant
(Rodriguez et al., 2008; Partida-Martínez and Heil, 2011; Peay et al.,
2016). However, several studies on foliar endophytic fungi have
shown that they can protect their host plants from herbivory and
pathogen attack, influencing therefore plant survival, fitness, and
even distribution (Albrectsen et al., 2010;
Alvarez-Loayza et al.,
2011; Mejía et al., 2014; Romeralo et al., 2015; Soliman et al.,
2015; Busby et al., 2016a).
Phaseolus lunatus (lima bean) is an important leguminose plant
that possesses direct and indirect chemical defense mechanisms
against herbivores, that may change with the plant ontogeny
(Ballhorn et al., 2008). Among these resistance mechanisms are
plant cyanogenesis (direct), that is the release of gaseous hydrogen
cyanide (Ballhorn et al., 2007), as well as herbivore-induced pro-
duction of volatile compounds (VOC) and secretion of extra floral
nectar (EFN) (both indirect) (Kost and Heil, 2008). Recently, the
intervention of microbial symbionts in the defense mechanisms of
lima bean against herbivores and pathogens was highlighted in
three different ways. First, rhizobial symbiosis influenced both VOC
production and VOC blend, increasing the production of indole, a N-
containing compound, that acts as a repellent to insect herbivores
(Ballhorn et al., 2013). Analogously, another study showed that
* Corresponding author. Km. 9.6 Libramiento Norte Carr. Irapuato-Le on, C.P.
36821, Irapuato, Gto., Mexico.
E-mail address: laila.partida@cinvestav.mx (L.P. Partida-Martínez).
1
Present address: Unidad de Microbiología B asica y Aplicada, Facultad de Cien-
cias Naturales, Universidad Aut onoma de Quer etaro, Av. de las Ciencias S/N, Juri-
quilla, 76230, Quer etaro, Qro, M exico.
Contents lists available at ScienceDirect
Fungal Ecology
journal homepage: www.elsevier.com/locate/funeco
http://dx.doi.org/10.1016/j.funeco.2016.11.004
1754-5048/© 2016 Elsevier Ltd and British Mycological Society. All rights reserved.
Fungal Ecology 26 (2017) 1e10