Root-specific metabolism: The biology and biochemistry of underground organs

Abstract

The roots of higher plants comprise a metabolically active and largely unexplored biological frontier. Some of their prime features include the ability to synthesize a remarkably diverse group of secondary metabolites, and to adjust their metabolic activities in response to different abiotic and biotic stresses. This adjustment includes the ability to exude a wide array of micro-and macromolecules into the rhizosphere and to phytoremediate toxic metals, with the potential to affect and alter the relationships between plants and both beneficial and deleterious soil-borne pathogens. In the past, research on root biology has been hampered by the underground nature of roots and the lack of suitable experimental systems to study root-root and root -microbe communications. However, recent progress in growing roots in isolation with other elements of the rhizosphere has greatly facilitated the study of root-specific metabolism and contributed to our understanding of this organ.

Proton-Transfer-Reaction Mass Spectrometry as a New Tool for Real Time Analysis of Root-Secreted Volatile Organic Compounds in Arabidopsis

“…The soil microorganism Agrobacterium rhizogenes causes the hairy root disease, which is characterized by the proliferation of adventitious roots at the infection site. Hairy roots are able to express root-specific biosynthetic pathways such as the synthesis of hyoscyamine, b-carbolines, and rosmarinic acid among other metabolites at levels equal to or greater than in the roots in planta (Flores et al, 1999;Bais et al, 2001Bais et al, , 2002aBais et al, , 2002bVivanco et al, 2002). In addition to secondary metabolites, hairy roots can produce and secrete bioactive proteins (Park et al, 2002).…”

“…Root exudates include low M r compounds like amino acids, organic acids, sugars, phenolics, and various secondary metab-olites and high M r compounds like mucilage and proteins (Roshina and Roshina, 1993). Although some chemical characterization of root exudates has been achieved for secondary metabolites, carbohydrates, and proteins (Bais et al, 2001;Knee et al, 2001;Park et al, 2002), much less is known about the volatile organic compounds (VOCs) released by roots.…”

The Role of Root-Produced Volatile Secondary Metabolites in Mediating Soil Interactions

“…Badri et al 2009;Bais et al 2001;Flores, Vivanco, and LoyolaVargas 1999;Wenke, Kai, and Piechulla 2010)}. Here, we will focus our attention to the role of plant VOCs exudation and their effect on various soil organisms including other plants, microorganisms, herbivores and particularly predators of the herbivore.…”

Allelopathic effects of the perennial herb Achillia santolina (Yarrow) on growth of selected species of soil algae in laboratory

“…H owev er, t he rol e played b y alleloc hemicals is mostl y interpret ed now in an ecol ogical w ay, usuall y in s ome m eans of plant defens e agai nst other plants, pe sts or diseas es. T he m odes of release for allelochemicals are vol atilizati on, residue dec ay, l eac hing or root exudation (Bais et al, 2001(Bais et al, & 2003. All elopathy holds out hope f or improv ements in crop produc tion through s uch m eans as discovering ec ofriendl y herbicides wit h new sites of acti on, harmles s cr ops but toxic t o w eeds and without formati on of dang erous residues (H aig, 2008).…”