DIFFERENTIAL RESPONSE OF FE-EFFICIENT CORN AND FE-INEFFICIENT CORN AND OAT TO PHYTOSIDEROPHORE RELEASED BY FE-EFFICIENT COKER-227 OAT

Iron-efficient Coker 227 oat responds to Fe-deficiency stress by producing a phytosiderophore that solubilizes Fe while Fe-inefficient TAM 0-312 does not. WF9 and ys1 corn are also Fe efficient and inefficient, respectively, but neither produce much phytosiderophore during Fe-deficiency stress. The objective of this study was to determine if phytosiderophore released by Fe-deficiency stressed Coker 227 oat would increase the availability of Fe to TAM 0-312 oat, WF9 corn, or ys1 corn. These cultivars were grown in a modified Steinberg solution with 1.2 mg/L Fe and in ratios of (Coker:TAM) 28:0, 21:7, 14:14, 7:21, and 0:28 and (Coker:corn) of 28:0, 21:1, 14:2, 7:3 and 0:4. Daily chlorosis ratings and periodic measurements of leaf and root Fe contents and phytosiderophore release were determined. Iron solubilized by the phytosiderophore released by Fe-stressed Coker 227 oat made Fe available to WF9 corn at the 21:1 and 14:2 Coker:WF9 ratios as reflected in chlorosis ratings and leaf Fe contents, but ys1 was incapable of obtaining Fe at any of the ratios. TAM 0-312 oat was less efficient in obtaining Fe from Fe-phytosiderophore than was WF9 corn. As the ratio of Coker:WF9 and Coker:TAM decreased, Coker 227 oat either became more cholorotic and/or leaf Fe declined, but this did not occur with Coker 227 growing with ys1 corn. Thus, ability to absorb Fe from Fe-phytosiderophore released by Fe-stressed Coker 227 oat was in the order WF9 corn > TAM 0-312 oat > ys1 corn.