Humic Substances and Plant Defense Metabolism



Humic substances (HS) affect most plant metabolic processes. Regardless of their source, HS help regulate enzymatic systems related to primary, secondary, and defense metabolisms in response to environmental stress. Morphologically, the HS–plant interaction results in increased root length and the emanation of lateral roots. These morphological changes occur in response to complex regulatory and stress response processes activated by the application of HS and similar chemical fractions. Given that the roots are the main plant organs that interact with HS, HS–root interaction mechanisms are one of the most important topics in HS–plant research. Specifically, there is a known biochemical relationship between humic compounds and major plant metabolic processes. New findings about the modes of metabolite action in plants have increased our understanding of how HS help to optimize plant metabolism. Advanced technologies, such as large-scale and spectroscopy, have also increased our understanding of the modes of action of HS. The application of techniques such as amplified fragment length polymorphism (AFLP) and microarray analysis in study of HS-treated plants has demonstrated that approximately 6.1–9 % of differentially expressed genes correspond to metabolic pathways that are associated with defense mechanisms in response to stimuli. These results suggest that HS induce plant adaptive responses to environmental stress. In this study, we discuss how HS contribute to improved plant performance through complex metabolic mechanisms. We apply new findings about the modes of action of metabolites related to antioxidant mechanisms to understand HS modes of action and examine HS effects in plants by using spectroscopic techniques to study root interactions. We also propose a framework for investigating the use of HS in agriculture to improve the growth of food plants grown in high-stress environments.


Humic Substance Humic Acid Fulvic Acid Humic Fraction Radical Oxygen Species 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



To the TWAS/CNPq for the grant to Andres Calderin Garcia and FAPERJ/Prioridade Rio and CNPq/UNIVERSAL to Ricardo L. Berbara.


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© Springer Science+Business Media New York 2014

Authors and Affiliations

  1. 1.Agronomy Institute, Department of Soil SciencesFederal Rural University of Rio de Janeiro (UFRRJ)Rio de JaneiroBrazil
  2. 2.Department of ChemistryAgricultural University of HavanaSan Jose de las LajasCuba

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