473
ecosystem sustainability (Gianinazzi et al. 2010; Njeru 2018). They form symbiotic relationships with the roots of most agricultural crops (ca. 80%), improving
the nutritional status of their hosts and protecting them from pathogenic
microorganisms and abiotic stresses (Smith and Read 2008; Berta et al. 2013).
AMF are also important because of their ability to improve the sustainability of
agricultural systems and plant communities and enhance soil biodiversity. The
underground hyphal networks formed by AMF can influence plant growth, nutrient acquisition as well as plant-plant interactions. Rondon et al. (2006) and
Ondieki et al. (2017) reported that common beans and cowpeas colonized by
AMF accumulated approximately 60% more phosphorus content compared to
crops without mycorrhizal colonization. This highlights the importance of effectively managing AMF for maximum utilization of phosphates thus minimizing the
use of inorganic phosphate fertilizers.
Plant genotypes differ in their dependency on AMF, as reflected by various
mycorrhizal colonization and growth performance of host plants after mycorrhizal
inoculation (Aquino et al. 2015; Yang et al. 2016; Oruru et al. 2018). Therefore,
breeding programs should consider mycorrhizal responsiveness which varies among
genotypes (Chu et al. 2013). Moreover, the influence of AMF root colonization by
soil properties has also been reported. Van Tuinen et al. (2016) reported variation in
AMF colonization between plots due to soil characteristics in each plot while working on interaction between AMF and Vitis vinifera (L). Therefore, there is a need to
establish suitable soil characteristics for maximum utilization of AMF for improved
maize production.
Nitrogen is one of the most essential nutrients for plants since it facilitates various metabolic processes that regulate plant growth and development (Ondieki et al.
2017; Razaq et al. 2017). This is because it is a major constituent of important
organic compounds, proteins, enzymes, amino acids and nucleic acids. According
to Leghari et al. (2016), nitrogen availability not only improves plant yield but also
the quality of food produced. To enhance nitrogen content in the soil, inorganic
nitrogen fertilizers have been utilized widely in the past (Otieno et al. 2009).
However, nitrogenous fertilizers contribute to greenhouse gas (GHG) emissions
globally (Argaw 2013; Erbas 2017), as well as being costly and beyond the reach of
most small-scale farmers. There is therefore a need for cheaper and environmentally
friendly alternative sources of nitrogen.
Biological nitrogen fixation (BNF), which utilizes the symbiotic interaction
between diazotrophic bacteria (rhizobia) and legumes, is a viable alternative to
inorganic nitrogen fertilizer use (Oliveira et al. 2010). BNF can sustainably
improve nitrogen input in agroecosystems and reduce the need for inorganic fertilizers (Lindstrom et al. 2010). In turn, this will mitigate the negative impacts of
inorganic fertilizer production and utilization on the global nitrogen cycle and
global warming (Garg and Geetanjali 2007). Based on transcriptome analyses, the
legume plant genotype has a significant influence on symbiosis with rhizobia
other than the rhizobia strain. Therefore, the ability to have effective symbiotic
Exploiting Arbuscular Mycorrhizal Fungi-Rhizobia-Legume Symbiosis to Increase…
ecosystem sustainability (Gianinazzi et al. 2010; Njeru 2018). They form symbiotic relationships with the roots of most agricultural crops (ca. 80%), improving
the nutritional status of their hosts and protecting them from pathogenic
microorganisms and abiotic stresses (Smith and Read 2008; Berta et al. 2013).
AMF are also important because of their ability to improve the sustainability of
agricultural systems and plant communities and enhance soil biodiversity. The
underground hyphal networks formed by AMF can influence plant growth, nutrient acquisition as well as plant-plant interactions. Rondon et al. (2006) and
Ondieki et al. (2017) reported that common beans and cowpeas colonized by
AMF accumulated approximately 60% more phosphorus content compared to
crops without mycorrhizal colonization. This highlights the importance of effectively managing AMF for maximum utilization of phosphates thus minimizing the
use of inorganic phosphate fertilizers.
Plant genotypes differ in their dependency on AMF, as reflected by various
mycorrhizal colonization and growth performance of host plants after mycorrhizal
inoculation (Aquino et al. 2015; Yang et al. 2016; Oruru et al. 2018). Therefore,
breeding programs should consider mycorrhizal responsiveness which varies among
genotypes (Chu et al. 2013). Moreover, the influence of AMF root colonization by
soil properties has also been reported. Van Tuinen et al. (2016) reported variation in
AMF colonization between plots due to soil characteristics in each plot while working on interaction between AMF and Vitis vinifera (L). Therefore, there is a need to
establish suitable soil characteristics for maximum utilization of AMF for improved
maize production.
Nitrogen is one of the most essential nutrients for plants since it facilitates various metabolic processes that regulate plant growth and development (Ondieki et al.
2017; Razaq et al. 2017). This is because it is a major constituent of important
organic compounds, proteins, enzymes, amino acids and nucleic acids. According
to Leghari et al. (2016), nitrogen availability not only improves plant yield but also
the quality of food produced. To enhance nitrogen content in the soil, inorganic
nitrogen fertilizers have been utilized widely in the past (Otieno et al. 2009).
However, nitrogenous fertilizers contribute to greenhouse gas (GHG) emissions
globally (Argaw 2013; Erbas 2017), as well as being costly and beyond the reach of
most small-scale farmers. There is therefore a need for cheaper and environmentally
friendly alternative sources of nitrogen.
Biological nitrogen fixation (BNF), which utilizes the symbiotic interaction
between diazotrophic bacteria (rhizobia) and legumes, is a viable alternative to
inorganic nitrogen fertilizer use (Oliveira et al. 2010). BNF can sustainably
improve nitrogen input in agroecosystems and reduce the need for inorganic fertilizers (Lindstrom et al. 2010). In turn, this will mitigate the negative impacts of
inorganic fertilizer production and utilization on the global nitrogen cycle and
global warming (Garg and Geetanjali 2007). Based on transcriptome analyses, the
legume plant genotype has a significant influence on symbiosis with rhizobia
other than the rhizobia strain. Therefore, the ability to have effective symbiotic
Exploiting Arbuscular Mycorrhizal Fungi-Rhizobia-Legume Symbiosis to Increase…