126
Phytotechnology with Biomass Production
12J1; peas (Pisum sativum) and Pseudomonas putida VM1450 with the destruction of 2,4-dichlorophenoxyacetic acid. The potential of endophytic bacteria to enhance phytoremediation of soil contaminated with diesel fuel was
compared with the potential of rhizobacteria (Afzal et al., 2012; Andria et al.,
2009). Endophytes showed higher levels of colonization, especially in roots
and shoots, and higher levels of expression of alkane-cleaving genes (alkB
and CYP153) than the rhizobacterial strain. Inoculated endophytes colonize
both the rhizosphere and the endosphere but are also metabolically active
with respect to the decomposition of organic pollutants in soil and in plant
itself (Afzal et al., 2014).
7.1.2 Rhizobacteria
The significant role of rhizobacteria in plant life is illustrated (Adesemoye &
Kloepper, 2009; Afzal et al., 2014; Hayat et al., 2010; Mitter et al., 2016; OrtízCastro et al., 2009; Simpson et al., 2011). Active secretion by root cells of various substances, such as sugars, polysaccharides, amino acids, tricarboxylic
acids, oxalic, malic, succinic and citric acids, fatty acids, sterols, phenols,
enzymes and proteins, provides nutrients to microorganisms: inside root tissues and to root surfaces (rhizoplane) as well as to rhizosphere in close surroundings of roots (Döbereiner, 1989; Fan et al., 2018; Mitter et al., 2016). Plant
exudates contribute to xenobiotic degradation through the following actions
(Anderson & Coats, 1995):
• selective increasing in microorganisms destructors;
• increasing metabolism associated with growth;
• induction of joint metabolism with some microorganisms that have
genes and plasmids responsible for degradation of pollutants.
Microorganisms secrete phytohormones, small molecules, or volatile compounds that can act directly or indirectly activate plant immunity or regulate
plant growth and morphogenesis (Bhattacharyya & Jha, 2012; Glick, 2003;
Ortíz-Castro et al., 2009). Indirect stimulation of plant growth is caused by
reduction or preventing the harmful influence of phytotoxic compounds. It
may include reducing iron prepared for phytopathogens in the rhizosphere;
synthesis of enzymes that lyse fungal cell walls; competition with harmful
microorganisms for their location on plant roots surface. Direct stimulation
of plant growth by bacteria is caused by following factors (Dimkpa et al.,
2008; Glick, 2003; Loper & Henkels, 1999; Rodríguez et al., 2006):
• providing plants with substances that are synthesized by bacteria
(e.g., microbial nitrogen fixation);
• synthesis of siderophores, which can dissolve and accumulate iron
from soil and supply it to plant cells;
Phytotechnology with Biomass Production
12J1; peas (Pisum sativum) and Pseudomonas putida VM1450 with the destruction of 2,4-dichlorophenoxyacetic acid. The potential of endophytic bacteria to enhance phytoremediation of soil contaminated with diesel fuel was
compared with the potential of rhizobacteria (Afzal et al., 2012; Andria et al.,
2009). Endophytes showed higher levels of colonization, especially in roots
and shoots, and higher levels of expression of alkane-cleaving genes (alkB
and CYP153) than the rhizobacterial strain. Inoculated endophytes colonize
both the rhizosphere and the endosphere but are also metabolically active
with respect to the decomposition of organic pollutants in soil and in plant
itself (Afzal et al., 2014).
7.1.2 Rhizobacteria
The significant role of rhizobacteria in plant life is illustrated (Adesemoye &
Kloepper, 2009; Afzal et al., 2014; Hayat et al., 2010; Mitter et al., 2016; OrtízCastro et al., 2009; Simpson et al., 2011). Active secretion by root cells of various substances, such as sugars, polysaccharides, amino acids, tricarboxylic
acids, oxalic, malic, succinic and citric acids, fatty acids, sterols, phenols,
enzymes and proteins, provides nutrients to microorganisms: inside root tissues and to root surfaces (rhizoplane) as well as to rhizosphere in close surroundings of roots (Döbereiner, 1989; Fan et al., 2018; Mitter et al., 2016). Plant
exudates contribute to xenobiotic degradation through the following actions
(Anderson & Coats, 1995):
• selective increasing in microorganisms destructors;
• increasing metabolism associated with growth;
• induction of joint metabolism with some microorganisms that have
genes and plasmids responsible for degradation of pollutants.
Microorganisms secrete phytohormones, small molecules, or volatile compounds that can act directly or indirectly activate plant immunity or regulate
plant growth and morphogenesis (Bhattacharyya & Jha, 2012; Glick, 2003;
Ortíz-Castro et al., 2009). Indirect stimulation of plant growth is caused by
reduction or preventing the harmful influence of phytotoxic compounds. It
may include reducing iron prepared for phytopathogens in the rhizosphere;
synthesis of enzymes that lyse fungal cell walls; competition with harmful
microorganisms for their location on plant roots surface. Direct stimulation
of plant growth by bacteria is caused by following factors (Dimkpa et al.,
2008; Glick, 2003; Loper & Henkels, 1999; Rodríguez et al., 2006):
• providing plants with substances that are synthesized by bacteria
(e.g., microbial nitrogen fixation);
• synthesis of siderophores, which can dissolve and accumulate iron
from soil and supply it to plant cells;