Table I. Principal compounds found in root exudates with negative and positive effects on plant productivity.

Species	Compound	Structure	Function	Effect on Productivity	Reference
Alliaria petiolata	Benzyl isothiocyanate		Inhibits the growth of ectomycorrhizal fungi	Negative	Stinson et al. (2006); Wolfe et al. (2008)
Centaurea maculosa	(−)-Catechin		Reduces the growth of native plant species	Negative	Bais et al. (2003); Weir et al. (2003)
Juglans nigra	Juglone (5-hydroxy-1,4-napthoquinone)		Inhibits the growth of crops, mainly shoot elongation	Negative	Rietveld (1983); Jose and Gillespie (1998)
Phragmites australis	Gallic acid (3,4,5-trihydroxybenzoic acid)		Allelopathic agent	Negative	Saltonstall (2002)
Arabidopsis	Rhizathalene A		Defense against herbivores	Positive	Vaughan et al. (2013)
Rice	Momilactone A		Antimicrobial	Positive	Kato-Noguchi et al. (2008)
	Momilactone B		Allelopathic agent	Positive	Kato-Noguchi (2004)
	Phytocassanes A to Ea		Antimicrobial agent	Positive	Toyomasu et al. (2008)
Sorghum	Sorgoleone (2-hydroxy-5-methoxy-3-[(8′Z,11′Z)-8′,11′,14′-pentadecatriene]-p-benzaquinone)		Allelopathic agent	Positive	Uddin et al. (2014)
Maize	Benzoxazinoids (2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one)		Antimicrobial agent	Positive	Neal et al. (2012)

^aPhytocassane A, R1, R2, R3 = H, OH, O; phytocassane B, OH, OH, OH; phytocassane C, OH, H, OH; phytocassane D, H, O, OH; phytocassane E, OH, H, O.