Plants were harvested 12 months after the mycelial inoculation. Root exudates were collected, filtered and lyophilized as described by Silva et al. (2004). Lyophilized root exudates were re-suspended with ultrapure water (20 mL). Organic acids were determined by HPLC (Laboratoire LIVE, Nouméa, Université de
Nouvelle-Calédonie) with the following conditions: HPLC Waters Alliance system® , with PDA detector at 210 nm (Waters SA, Guyancourt, France); column ODS 100 V 4.6 mm diameter, 250 mm length,