Selecting Native Arbuscular Mycorrhizal Fungi to Promote Cassava Growth and Increase Yield under Field Conditions

Abstract

The use of arbuscular mycorrhizal fungal (AMF) inoculation in sustainable agriculture is now widespread worldwide. Although the use of inoculants consisting of native AMF is highly recommended as an alternative to commercial ones, there is no strategy to allow the selection of efficient fungal species from natural communities. The objective of this study was (i) to select efficient native AMF species (ii) evaluate their impact on nematode and water stresses, and (iii) evaluate their impact on cassava yield, an important food security crop in tropical and subtropical regions. Firstly, native AMF communities associated with cassava rhizospheres in fields were collected from different areas and 7 AMF species were selected, based upon their ubiquity and abundance. Using these criteria, two morphotypes (LBVM01 and LBVM02) out of the seven AMF species selected were persistently dominant when cassava was used as a trap plant. LBVM01 and LBVM02 were identified as Acaulospora colombiana (most abundant) and Ambispora appendicula, respectively, after phylogenetic analyses of LSU-ITS-SSU PCR amplified products. Secondly, the potential of these two native AMF species to promote growth and enhance tolerance to root-knot nematode and water stresses of cassava (Yavo variety) was evaluated using single and dual inoculation in greenhouse conditions. Of the two AMF species, it was shown that A. colombiana significantly improved the growth of the cassava and enhanced tolerance to water stress. However, both A. colombiana and A. appendicula conferred bioprotective effects to cassava plants against the nematode Meloidogyne spp., ranging from resistance (suppression or reduction of the nematode reproduction) or tolerance (low or no suppression in cassava growth). Thirdly, the potential of these selected native AMF to improve cassava growth and yield was evaluated under field conditions, compared to a commercial inoculant. In these conditions, the A. colombiana single inoculation and the dual inoculation significantly improved cassava yield compared to the commercial inoculant. This is the first report on native AMF species exhibiting multiple benefits for cassava crop productivity, namely improved plant growth and yield, water stress tolerance and nematode resistance.

Distinct arbuscular mycorrhizal fungal communities associate with different manioc landraces and Amazonian soils

“…5). In previous spore-based studies, Rhizophagus irregularis (Ceballos et al 2013), Paraglomus occultum (Dodd et al 1990), Acaulospora colombiana, and Ambispora appendiculata (Séry et al 2016) were reported as AM fungal species with affinity for manioc. Among them, R. irregularis and P. occultum were present in our study area, but none of the four species named were among the most important symbionts of manioc in our study.…”

“…Many studies have demonstrated the positive effect of AM on manioc performance in comparison with non-mycorrhizal treatments (Ceballos et al 2013;Dodd et al 1990;Fagbola et al 1998;Sieverding 1990; Sieverding and Howeler 1985;Sieverding and Toro 1990). AM association in manioc has been studied by assessing AM colonization of manioc roots, and by characterizing soil AM fungal communities co-occurring with manioc, in the hope of identifying suitable AM fungal symbionts for manioc (Séry et al 2016;Straker et al 2010;Voko et al 2013). The latter approach has mainly relied on descriptions of AM fungal spores isolated from soil or trap cultures, as until recently, limited methods were available for studying AM fungi actively involved in the symbiosis (i.e., within plant root tissues) (Anderson and Cairney 2004;Öpik et al 2006).…”

“…The latter approach has mainly relied on descriptions of AM fungal spores isolated from soil or trap cultures, as until recently, limited methods were available for studying AM fungi actively involved in the symbiosis (i.e., within plant root tissues) (Anderson and Cairney 2004;Öpik et al 2006). Based on descriptions of AM fungal spores co-occurring with manioc, Rhizophagus irregularis (Ceballos et al 2013), Paraglomus occultum (Dodd et al 1990), Acaulospora colombiana, and Ambispora appendiculata (Séry et al 2016) have been reported as commonly encountered symbionts for manioc.…”

Diversity of Arbuscular Mycorrhizal Fungi in Forest Ecosystems of Brazil: A Review

“…In fact, the AMF morphotype to be employed as AMF inoculant should be effective to promote plant growth, increase the plant tolerance to environmental stresses, but they need to be competitive against indigenous AMF species (e.g. Séry et al, 2016;Vilcatoma-Medina et al, 2018). In spite of several experiments, it remains unresolved which of the AMF species that would be the most appropriated to be employed as AMF inoculant in many forest species (e.g.…”

Research Article Genetic diversity as tool to identify standard leaf nutrients in cassava genotypes

“…P is essential for lipid membrane and ATP synthesis which is the energy currency for plant metabolism (Marschner, 1995;Taiz et al, 2015). Therefore, plants absorbing high levels of N and P may increase the cassava growth and yield (Séry et al, 2016). Despite differences among genotypes for such nutrients, the NC shown in table 2 could be used as reference values since the mean yield was ca.…”