living inside the spaces between cells of plants’ tissues. Colonizing microbial
communities are often specific to the different plant compartments or organs,
including roots, stem, leaves, flowers, as well as fruits and seeds (Compant et al.
2010). Schulz and Boyle (2006) noted that endophytic bacteria are located in plant
tissues beneath the epidermal cell layers, colonizing the internal tissues and
establishing different interactions that include symbiosis, mutualism, or
commensalism.
Authors like Compant et al. (2010) and Zheng et al. (2016) mention that this kind
of microorganisms establishes a harmonious relationship within the plants and does
not cause negative effects on their health. Luo et al. (2011) reported that these
bacteria have been isolated from a wide range of plant species, suggesting an
ubiquitous existence of them.
Even Dharni et al. (2014) and Ma et al. (2015b, 2016) noted that it is known that
PGPB participate on plants’ growth and heavy metal phytoremediation in polluted
soils; He et al. (2013), Chen et al. (2014), Babu et al.(2015), and Ma et al. (2015a)
resumed that there is little knowledge about plant endophytic bacteria interactions
and their potential role in phytoremediation. Phetcharat and Duangpaeng (2012)
named also these bacteria as plant growth-promoting endophytic (PGPE) bacteria
and suggested that their colonization and plants’ propagation enhance soil fertility
and stimulate the host plant development by providing growth regulators. It also has
been demonstrated by Ma et al. (2011) that endophytic bacteria may help host plants
to adapt under unfavorable environmental conditions and increase the
phytoremediation efficiency, promoting the plants’ growth, alleviating the metal
stress, reducing metal phytotoxicity, and finally altering the metals’ bioavailability
and translocation of them inside the plants.
Finally, to ensure that the isolated bacteria are really a plants’ endophyte, Visioli
et al. (2014) and Maropola et al. (2015) noted that all the methods reviewed that are
used to isolate and characterize them include the surface sterilization of the host
tissues and isolation of the endophytic bacteria using appropriate growth media and
the bacterial detection and identification by molecular methods (e.g., direct amplification of bacterial DNA from colonized plant tissues).
4 Functional Diversity Definitions in Ecological Context
Petchey and Gaston (2006) noted that Zak et al. (1994) and Stevens et al. (2003)
reviewed the use of the term “functional diversity” and commented that it has grown
exponentially over the last decade and has been managed in studies of marine,
freshwater, and terrestrial ecosystems; actually, this spanned a wide range of taxa
including bacteria. Even now there isn’t a standard knowledge about how to define
functional diversity, how to measure it, and how to assess its performance. Petchey
and Gaston (2006) established that in general, it is known that functional diversity
generally involves the understanding of communities and ecosystems based on what
organisms do rather than on their evolutionary history and noted that this concept
10 Functional Diversity of Plant Endophytes and Their Role in Assisted. . .
239
communities are often specific to the different plant compartments or organs,
including roots, stem, leaves, flowers, as well as fruits and seeds (Compant et al.
2010). Schulz and Boyle (2006) noted that endophytic bacteria are located in plant
tissues beneath the epidermal cell layers, colonizing the internal tissues and
establishing different interactions that include symbiosis, mutualism, or
commensalism.
Authors like Compant et al. (2010) and Zheng et al. (2016) mention that this kind
of microorganisms establishes a harmonious relationship within the plants and does
not cause negative effects on their health. Luo et al. (2011) reported that these
bacteria have been isolated from a wide range of plant species, suggesting an
ubiquitous existence of them.
Even Dharni et al. (2014) and Ma et al. (2015b, 2016) noted that it is known that
PGPB participate on plants’ growth and heavy metal phytoremediation in polluted
soils; He et al. (2013), Chen et al. (2014), Babu et al.(2015), and Ma et al. (2015a)
resumed that there is little knowledge about plant endophytic bacteria interactions
and their potential role in phytoremediation. Phetcharat and Duangpaeng (2012)
named also these bacteria as plant growth-promoting endophytic (PGPE) bacteria
and suggested that their colonization and plants’ propagation enhance soil fertility
and stimulate the host plant development by providing growth regulators. It also has
been demonstrated by Ma et al. (2011) that endophytic bacteria may help host plants
to adapt under unfavorable environmental conditions and increase the
phytoremediation efficiency, promoting the plants’ growth, alleviating the metal
stress, reducing metal phytotoxicity, and finally altering the metals’ bioavailability
and translocation of them inside the plants.
Finally, to ensure that the isolated bacteria are really a plants’ endophyte, Visioli
et al. (2014) and Maropola et al. (2015) noted that all the methods reviewed that are
used to isolate and characterize them include the surface sterilization of the host
tissues and isolation of the endophytic bacteria using appropriate growth media and
the bacterial detection and identification by molecular methods (e.g., direct amplification of bacterial DNA from colonized plant tissues).
4 Functional Diversity Definitions in Ecological Context
Petchey and Gaston (2006) noted that Zak et al. (1994) and Stevens et al. (2003)
reviewed the use of the term “functional diversity” and commented that it has grown
exponentially over the last decade and has been managed in studies of marine,
freshwater, and terrestrial ecosystems; actually, this spanned a wide range of taxa
including bacteria. Even now there isn’t a standard knowledge about how to define
functional diversity, how to measure it, and how to assess its performance. Petchey
and Gaston (2006) established that in general, it is known that functional diversity
generally involves the understanding of communities and ecosystems based on what
organisms do rather than on their evolutionary history and noted that this concept
10 Functional Diversity of Plant Endophytes and Their Role in Assisted. . .
239