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Synergistic effects of arbuscular mycorrhizal fungi and plant growth-promoting bacteria benefit maize growth under increasing soil salinity

Publication . Moreira, Helena; Pereira, Sofia I. A.; Vega, Alberto; Castro, Paula; Marques, Ana P. G. C.

Salt-affected soils are a major problem worldwide for crop production. Bioinocula such as plant growth-promoting bacteria (PGPB) and arbuscular mycorrhizal fungi (AMF) can help plants to thrive in these areas but interactions between them and with soil conditions can modulate the effects on their host. To test potential synergistic effects of bioinoculants with intrinsically different functional relationships with their host in buffering the effect of saline stress, maize plants were grown under increasing soil salinity (0–5 g NaCl kg−-1 soil) and inoculated with two PGPB strains (Pseudomonas reactans EDP28, and Pantoea alli ZS 3-6), one AMF (Rhizoglomus irregulare), and with the combination of both. We then modelled biomass, ion and nutrient content in maize plants in response to increasing salt concentration and microbial inoculant treatments using generalized linear models. The impacts of the different treatments on the rhizosphere bacterial communities were also analyzed. Microbial inoculants tended to mitigate ion imbalances in plants across the gradient of NaCl, promoting maize growth and nutritional status. These effects were mostly prominent in the treatments comprising the dual inoculation (AMF and PGPB), occurring throughout the gradient of salinity in the soil. The composition of bacterial communities of the soil was not affected by microbial treatments and were mainly driven by salt exposure. The tested bioinocula are most efficient for maize growth and health when co-inoculated, increasing the content of K+ accompanied by an effective decrease of Na+ in plant tissues. Moreover, synergistic effects potentially contribute to expanding crop production to otherwise unproductive soils. Results suggest that the combination of AMF and PGPB leads to interactions that may have a potential role in alleviating the stress and improve crop productivity in salt-affected soils.

2020Journal article

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Mine land valorization through energy maize production enhanced by the application of plant growth-promoting rhizobacteria and arbuscular mycorrhizal fungi

Publication . Moreira, Helena; Pereira, Sofia I. A.; Marques, Ana P. G. C.; Rangel, António O. S. S.; Castro, Paula M. L.

The use of heavy metals (HM) contaminated soils to grow energy crops can diminish the negative impact of HM in the environment improving land restoration. The effect of two PGPR (B1—Chryseobacterium humi ECP37T and B2—Pseudomonas reactans EDP28) and an AMF (F—Rhizophagus irregularis) on growth, Cd and Zn accumulation, and nutritional status of energy maize plants grown in a soil collected from an area adjacent to a Portuguese mine was assessed in a greenhouse experiment. Both bacterial strains, especially when co-inoculated with the AMF, acted as plant growth-promoting inoculants, increasing root and shoot biomass as well as shoot elongation. Cadmium was not detected in the maize tissues and a decrease in Zn accumulation was observed for all microbial treatments in aboveground and belowground tissues—with inoculation of maize with AMF and strain B2 leading to maximum reductions in Zn shoot and root accumulation of up to 48 and 43 %, respectively. Although microbial single inoculation generally did not increase N and P levels in maize plants, co-inoculation of the PGPR and the AMF improved substantially P accumulation in roots. The DGGE analysis of the bacterial rhizosphere community showed that the samples inoculated with the AMF clustered apart of those without the AMF and the Shannon-Wiener Index (H′) increased over the course of the experiment when both inoculants were present. This work shows the benefits of combined inoculation of AMF and PGPR for the growth energy maize in metal contaminated soils and their potential for the application in phytomanagement strategies.

2016Journal article

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Effects of the inoculation with soil microbiota onmaize grown in saline soils

Publication . Moreira, Helena; Pereira, Sofia A.; Castro, Paula M. L.; Marques, Ana P. G. C.

2015Conference object

Open access

Growth promotional traits of three pgpr: possible uses for phytoremediation of degraded soils

Publication . Moreira, Helena; Pereira, Sofia A.; Vegas, Alberto L.; Rangel, António O. S. S.; Castro, Paula M. L.; Marques, Ana P. G. C.

Maize is a fast-growing and high yield crop with both energy value and remediation potential. Plant growth promoting rhizobacteria (PGPR) are a biological tool available to enhance plant establishment in degraded or depleted environments such as the case of saline soils or heavy-metal contaminated land. Although PGPR are able to produce metabolites such as siderophores, HCN and ammonia, or solubilize nutrients such as phosphate, these beneficial traits for the plant may be influenced by exposure to excessive levels of such contaminants. In this study, three PGPR (Pseudomonas fluorescens, Ralstonia eutropha and Cryseobacterium humi) were screened for those traits in the presence of different levels of Cd and Zn, and also to different salinization conditions. Their ability to influence maize germination and root and shoot elongation was also analyzed. Results showed that the level of exposure generally affected the ability of the tested strains to produce plant growth promoting substances. However, dissimilar sensibilities in the behavior of the different strains were observed when exposed to similar stress conditions. These differences were also noticeable in the plant development, with the tested PGPR generally positively influencing the analyzed parameters. Results suggest that PGPR can be exploited to promote stress relief of maize when grown in degraded land. Such knowledge may provide a new insight concerning the advantages of such biotechnologically based tools for phytoremediation.

2014Conference object

Open access

Promotion of sunflower growth under saline water irrigation by the inoculation of beneficial microorganisms

Publication . Pereira, Sofia I. A.; Moreira, Helena; Argyras, Konstantinos; Castro, Paula M. L.; Marques, Ana P. G. C.

Soil salinization and fresh water scarcity are amongst the main environmental/agricultural problems, with serious consequences to plant productivity. Amelioration with microorganisms can enhance plant performance under salt conditions. The aim of this work was to evaluate the role of beneficial rhizospheric microorganisms on the growth of sunflower plants irrigated with salinized water with particular attention to nutrient balance and biochemical responses. Sunflower seedlings were inoculated with the arbuscular mycorrhizal fungi Rhizophagus irregularis, the rhizobacteria Chryseobacterium humi ECP37T, or the bacterial endophyte Ochrobacterium haematophilum ZR3-5, and with a mixed inocula of those microorganisms. Plant growth, nutrient accumulation and lipid peroxidation in plant tissues, and the activity of soil enzymes, were evaluated. Irrigating sunflower plants with saline water resulted in decreases in growth and negative effects in salt stress markers, however the application of bioinoculants enhanced biomass production and accumulation of K+, Mg2+, Ca2+, N and P, reduced Na+ levels in tissues and increased plant antioxidative response. This study contributes to devise inoculation strategies for sunflower cultivation in areas prone to salinization.

2016Journal article

Restricted access