The rhizosphere, the thin soil layer influenced by the presence of plant roots has different physico-chemical properties from the bulk soil because of the active or passive rhizodepositions, which sustain larger and more active microbial populations in the rhizosphere than in bulk soil, and this plays a key role in soil organic matter decomposition and nutrient solubilization. The rhizosphere is chemically complex and dynamic microenvironment and this makes it difficult to study. Progresses in the study of the rhizosphere can be achieved by using rhizoboxes allowing the plant growth and precise sampling of rhizosphere. Plants select microbial bacterial and fungal populations in the rhizosphere during the plant growth, and while plant mechanisms involved in increased N uptake efficiency have been clarified, the importance of the rhizosphere microbial communities in nutrient availability to plants are still poorly understood. Nitrogen is the main nutrient limiting the plant growth and the crop yields and today, the nitrogen use efficiency (NUE) of crops at field scale is still relatively low, with detrimental effects on groundwater quality and atmosphere due to NO3- leaching and NH3 and nitrous oxide emissions caused be excessive fertilization, and large efforts have been carried out to increase the NUE to enhance the crop production and reduce the environmental impact of agriculture, especially through plant breeding and preparation of fertilizers with slow N release. We evaluated the changes in the biochemical activity and microbial community structure induced by the inbred maize (Zea mais L.) lines Lo5 and T250 characterized by high and low NUE using rhizobox experiments. The adopted experimental approach allowed to describe the relative plant induced changes on the different rhizosphere chemical and microbiological components and provide information to improve the crop NUE. In this work we studied the changes in the biochemical activity and microbial community structure in the rhizosphere of the inbred maize (Zea mais L.) lines Lo5 and T250 characterized by high and low NUE, repectively, using rhizobox experiments. Because of the importance of the proteolytic activity in soil N mineralization, the proteolytic activity in the rhizosphere of the two maize lines was also studied by the assessment of the diversity and abundance of the apr and npr genes coding for coding for alkaline protease and neutral metalloprotease, respectively, and determination of the protease activity. The results showed that the Lo5 plant, having the higher NUE, induced the greater modification in the rhizosphere chemical properties, induced significantly faster depletion of inorganic N, higher bacteria diversity, proteolytic populations and protease activity. The importance of the plant activity in modifying microbial community structure, protease functions and rhizosphere biochemical activity will be presented.

Microbial community structure and proteolytic activity in the rhizosphere of maize plants differing in nitrogen use efficiency

Giagnoni L.;
2014-01-01

Abstract

The rhizosphere, the thin soil layer influenced by the presence of plant roots has different physico-chemical properties from the bulk soil because of the active or passive rhizodepositions, which sustain larger and more active microbial populations in the rhizosphere than in bulk soil, and this plays a key role in soil organic matter decomposition and nutrient solubilization. The rhizosphere is chemically complex and dynamic microenvironment and this makes it difficult to study. Progresses in the study of the rhizosphere can be achieved by using rhizoboxes allowing the plant growth and precise sampling of rhizosphere. Plants select microbial bacterial and fungal populations in the rhizosphere during the plant growth, and while plant mechanisms involved in increased N uptake efficiency have been clarified, the importance of the rhizosphere microbial communities in nutrient availability to plants are still poorly understood. Nitrogen is the main nutrient limiting the plant growth and the crop yields and today, the nitrogen use efficiency (NUE) of crops at field scale is still relatively low, with detrimental effects on groundwater quality and atmosphere due to NO3- leaching and NH3 and nitrous oxide emissions caused be excessive fertilization, and large efforts have been carried out to increase the NUE to enhance the crop production and reduce the environmental impact of agriculture, especially through plant breeding and preparation of fertilizers with slow N release. We evaluated the changes in the biochemical activity and microbial community structure induced by the inbred maize (Zea mais L.) lines Lo5 and T250 characterized by high and low NUE using rhizobox experiments. The adopted experimental approach allowed to describe the relative plant induced changes on the different rhizosphere chemical and microbiological components and provide information to improve the crop NUE. In this work we studied the changes in the biochemical activity and microbial community structure in the rhizosphere of the inbred maize (Zea mais L.) lines Lo5 and T250 characterized by high and low NUE, repectively, using rhizobox experiments. Because of the importance of the proteolytic activity in soil N mineralization, the proteolytic activity in the rhizosphere of the two maize lines was also studied by the assessment of the diversity and abundance of the apr and npr genes coding for coding for alkaline protease and neutral metalloprotease, respectively, and determination of the protease activity. The results showed that the Lo5 plant, having the higher NUE, induced the greater modification in the rhizosphere chemical properties, induced significantly faster depletion of inorganic N, higher bacteria diversity, proteolytic populations and protease activity. The importance of the plant activity in modifying microbial community structure, protease functions and rhizosphere biochemical activity will be presented.
2014
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11379/538226
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