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P. T. Lacava et al.
can cause significant damage to ecosystems through the processes of bioaccumulation and biomagnification due to their synthetic nature (Sarbadhikary and Mandal
2018). Consequently, interest in the development of new strategies to achieve more
sustainable agricultural practices has increased significantly in recent years (Azevedo
and Quecine 2019). In this context, biofertilizers are an interesting alternative to the
use of agrochemicals, as biofertilizers may be a safe substitute for agrochemicals
that would greatly minimize ecological disturbance from agriculture. Biofertilizers
are low-cost, eco-friendly tools, and their persistent use increases soil health and
fertility (Ngamau et al. 2014).
In this context, there is renewed scientific and commercial interest in the use of
endophytic microorganisms as biofertilizers because of their potential to improve
plant quality and growth and their close association with internal tissues of the host
plant (Schulz et al. 1998, 1999; Ngamau et al. 2014). Biofertilizers can improve
crop health by fixing nitrogen (Islam et al. 2013), solubilizing phosphate (Ghosh
et al. 2016), or promoting plant growth by producing plant growth-promoting factors
such as auxin (IAA) and gibberellins (Kang et al. 2014; Reetha et al. 2014). Plant
growth-promoting rhizobacteria (Vessey 2003) and vesicular-arbuscular mycorrhizae (Abbasi et al. 2015) are the microorganisms that are used most often as
biofertilizers. Recently, many researchers have also reported the use of endophytic
microorganisms in agricultural fields for crop improvement (Ngamau et al. 2014).
The term endophyte is applied to microorganisms that live within plant tissues
for all or part of their life cycles and cause no apparent infections or symptoms
of a disease (Strobel et al. 2004). Hallmann et al. (1997) described endophytes as
organisms that can be isolated from surface-sterilized plant parts or extracted from
inner tissues and that cause no damage to the host plant. Also, Azevedo and Araújo
(2007) suggested that endophytes are all microorganisms, whether culturable or
not, that inhabit the interior of plant tissues, cause no harm to the host, and do not
develop external structures. Endophytes have an intimate interaction with plants and
are capable of promoting plant growth. The use of these microorganisms at certain
stages of agricultural production can lead to a significant increase in productivity
or a reduction in inputs such as nitrogen and phosphate fertilizers (Malboobi et al.
2009; Rukshana-Begum and Tamilselvi 2016).
The plant growth-promoting effects of endophytes include increased plant height
and biomass in shoots, stems, and roots; formation of leaf and root hairs; lignification of the xylem vessels; and increased crop yield, as the ability of endophytes
to stimulate plant growth has been attributed to mechanisms such as phytohormone
production and phosphate solubilization (Ahmad et al. 2008). Some soil microorganisms solubilize the unavailable forms of inorganic P in the soil (Son et al. 2006;
Chai et al. 2011), and recent studies have confirmed that endophytic microorganisms
also possess this capacity (Vitorino et al 2012).
After nitrogen, phosphorus (P) is the second most limiting nutrient for plant development. It is only taken up in monobasic or dibasic soluble forms (Zaidi et al. 2006).
Phosphorus constitutes 0.2% of plant dry weight and is a structural component of
macromolecules such as nucleic acids, phospholipids, and adenosine triphosphate
(ATP) (Martins 2004). Phosphorus is an essential element for the establishment and
P. T. Lacava et al.
can cause significant damage to ecosystems through the processes of bioaccumulation and biomagnification due to their synthetic nature (Sarbadhikary and Mandal
2018). Consequently, interest in the development of new strategies to achieve more
sustainable agricultural practices has increased significantly in recent years (Azevedo
and Quecine 2019). In this context, biofertilizers are an interesting alternative to the
use of agrochemicals, as biofertilizers may be a safe substitute for agrochemicals
that would greatly minimize ecological disturbance from agriculture. Biofertilizers
are low-cost, eco-friendly tools, and their persistent use increases soil health and
fertility (Ngamau et al. 2014).
In this context, there is renewed scientific and commercial interest in the use of
endophytic microorganisms as biofertilizers because of their potential to improve
plant quality and growth and their close association with internal tissues of the host
plant (Schulz et al. 1998, 1999; Ngamau et al. 2014). Biofertilizers can improve
crop health by fixing nitrogen (Islam et al. 2013), solubilizing phosphate (Ghosh
et al. 2016), or promoting plant growth by producing plant growth-promoting factors
such as auxin (IAA) and gibberellins (Kang et al. 2014; Reetha et al. 2014). Plant
growth-promoting rhizobacteria (Vessey 2003) and vesicular-arbuscular mycorrhizae (Abbasi et al. 2015) are the microorganisms that are used most often as
biofertilizers. Recently, many researchers have also reported the use of endophytic
microorganisms in agricultural fields for crop improvement (Ngamau et al. 2014).
The term endophyte is applied to microorganisms that live within plant tissues
for all or part of their life cycles and cause no apparent infections or symptoms
of a disease (Strobel et al. 2004). Hallmann et al. (1997) described endophytes as
organisms that can be isolated from surface-sterilized plant parts or extracted from
inner tissues and that cause no damage to the host plant. Also, Azevedo and Araújo
(2007) suggested that endophytes are all microorganisms, whether culturable or
not, that inhabit the interior of plant tissues, cause no harm to the host, and do not
develop external structures. Endophytes have an intimate interaction with plants and
are capable of promoting plant growth. The use of these microorganisms at certain
stages of agricultural production can lead to a significant increase in productivity
or a reduction in inputs such as nitrogen and phosphate fertilizers (Malboobi et al.
2009; Rukshana-Begum and Tamilselvi 2016).
The plant growth-promoting effects of endophytes include increased plant height
and biomass in shoots, stems, and roots; formation of leaf and root hairs; lignification of the xylem vessels; and increased crop yield, as the ability of endophytes
to stimulate plant growth has been attributed to mechanisms such as phytohormone
production and phosphate solubilization (Ahmad et al. 2008). Some soil microorganisms solubilize the unavailable forms of inorganic P in the soil (Son et al. 2006;
Chai et al. 2011), and recent studies have confirmed that endophytic microorganisms
also possess this capacity (Vitorino et al 2012).
After nitrogen, phosphorus (P) is the second most limiting nutrient for plant development. It is only taken up in monobasic or dibasic soluble forms (Zaidi et al. 2006).
Phosphorus constitutes 0.2% of plant dry weight and is a structural component of
macromolecules such as nucleic acids, phospholipids, and adenosine triphosphate
(ATP) (Martins 2004). Phosphorus is an essential element for the establishment and