Table I.

Influx/Efflux (I/E) ratios for 16 amino acids near roots of four plant species

Alfalfa		Medic		Wheat		Maize
aa	I/E	aa	I/E	aa	I/E	aa	I/E
Met	3.00	Met	4.65	Met	6.45	Thr	5.93
Phe	2.55	Tyr	3.22	Thr	6.33	Met	4.78
Tyr	2.23	Gly	2.85	Lys	4.25	Asp	3.73
Asp	2.09	Leu	2.39	Phe	4.25	Arg	3.31
Leu	1.97	Lys	2.21	Arg	3.97	lle	2.97
Ile	1.94	His	2.15	Tyr	3.91	Ser	2.57
His	1.86	Glu	2.05	lle	2.57	Glu	2.31
Val	1.79	lle	2.05	Gly	2.55	Phe	2.31
Ser	1.71	Phe	1.86	Asp	2.35	His	2.07
Thr	1.58	Thr	1.59	Val	2.16	Lys	2.00
Arg	1.45	Arg	1.50	Leu	2.10	Val	1.96
Lys	1.40	Asp	1.45	Pro	1.93	Gly	1.94
Glu	1.39	Val	1.41	Ser	1.51	Leu	1.80
Gly	1.36	Pro	1.28	Glu	1.35	Tyr	1.60
Pro	1.25	Ala	1.20	Ala	1.17	Ala	1.37
Ala	1.23	Ser	1.14	His	1.05	Pro	1.17

Influx and efflux rates, determined as described in “Materials and Methods,” were obtained from axenic plants growing with 1.0 mm nitrate at pH 6.5. aa, Amino acid.