AI Article Synopsis

  • Plants can absorb organic nitrogen from soil through roots but struggle with accessing protein, a major nitrogen source.
  • Research on maize and wheat in sterile setups showed that most protease activity occurs on root surfaces instead of in the surrounding soil, indicating limited secretion of free proteases.
  • The findings suggest that while plant roots contribute to protease activity in the soil, their role in enhancing nitrogen uptake from soil proteins is not significant, especially under nitrogen-deficient conditions.

Article Abstract

Aims: The capacity of plant roots to directly acquire organic nitrogen (N) in the form of oligopeptides and amino acids from soil is well established. However, plants have poor access to protein, the central reservoir of soil organic N. Our question is: do plants actively secrete proteases to enhance the breakdown of soil protein or are they functionally reliant on soil microorganisms to undertake this role?

Methods: Growing maize and wheat under sterile hydroponic conditions with and without inorganic N, we measured protease activity on the root surface (root-bound proteases) or exogenously in the solution (free proteases). We compared root protease activities to the rhizosphere microbial community to estimate the ecological significance of root-derived proteases.

Results: We found little evidence for the secretion of free proteases, with almost all protease activity associated with the root surface. Root protease activity was not stimulated under N deficiency. Our findings suggest that cereal roots contribute one-fifth of rhizosphere protease activity.

Conclusions: Our results indicate that plant N uptake is only functionally significant when soil protein is in direct contact with root surfaces. The lack of protease upregulation under N deficiency suggests that root protease activity is unrelated to enhanced soil N capture.

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Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7567722PMC
http://dx.doi.org/10.1007/s11104-020-04719-6DOI Listing

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