Protein Expression Changes in Maize Roots in Response to Humic Substances
Humic substances are known to affect plant metabolism at different levels. We characterized humic substances extracted from earthworm feces by diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy and used them to treat corn, Zea mays L., seedlings to investigate changes in patterns of root protein expression. After root plasma membrane extraction and purification, proteins were separated by two-dimensional gel electrophoresis, and differential spot intensities were evaluated by image analysis. Finally, 42 differentially expressed proteins were identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The majority of them were downregulated by the treatment with humic substances. The proteins identified included malate dehydrogenase, ATPases, cytoskeleton proteins, and different enzymes belonging to the glycolytic/gluconeogenic pathways and sucrose metabolism. The identification of factors involved in plant responses to humic substances may improve our understanding of plant–soil cross-talk, and enable a better management of soil resources.
KeywordsDRIFT spectroscopy Humic substances LC-MS-MS Proteomics Sucrose metabolism Two-dimensional gel electrophoresis Zea mays L.
The authors thank Dr. Ornella Francioso of the Dipartimento di Scienze e Tecnologie Agroambientali, Università degli Studi di Bologna, for the DRIFT characterization of humic substances. The authors are also grateful to Prof. Angelo Fontana (CRIBI) for fruitful discussions.
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