DISSOLUTION OF FERRIC PHOSPHATE BY ALFALFA (MEDICAGO-SATIVA L) ROOT EXUDATES

Alfalfa (Medicago sativa L.) was grown in hydroponic culture to invest igate adaptation to Fe-deficiency. Root exudates released into the nut rient solution from Fe-deficient plants were trapped and condensed on an amberlite XAD-4 resin column. The diethyl ether fraction of these e xudates dissolved ferric phosphate remarkably. The dissolving capabili ty was about 62 times higher than that of root exudates obtained from Fe-sufficient plants in complete nutrient solution. The Fe-dissolving compound was separated and identified. It was a new natural compound w ith molecular formula C14H10O5 and was identified as 2-(3',5'-dihydrox yphenyl)-5,6-dihydroxybenzofuran by means of mass spectrometry and H-1 -nuclear magnetic resonance. This new compound worked as a phytoalexin and inhibited completely the fungal growth of Fusarium oxysporum f. s p. phaseoli.