Hybrid effects on the release of phytosiderophores in winter wheat (Triticum aestivum)

Fe (iron) deficiency is an important nutritional problem particularly in crop plants grown on calcareous soils. Phytosiderophore (PS) release has been suggested to be linked to the ability of graminaceous species and genotypes to overcome Fe-deficiency chlorosis. Thus, enhancing PS release is a critical step to improve Fe nutrition of plants grown on Fe stressed soils. The heterosis of PS release rate in common wheat was studied by analyzing PS release from roots of three hybrids and their four parents grown in Fe-deficiency nutrient solution under controlled environmental conditions. PS release rates were determined at two or three day intervals after onset of Fe-deficiency symptoms by the measurement of Fe mobilizing capacity of root exudates from freshly precipitated Fe III hydroxide. High amounts of phytosiderophores were released from the roots of all wheat genotypes under Fe-deficiency, and the amount progressively increased with the development of Fe-deficiency chlorosis. The results revealed that the hybrids had more sensitive feedback systems which secreted more phytosiderophores under Fe-deficiency than their parents. By analyzing the relationship between each hybrid and its parents, it was also found that the parents should be selected on the basis of the rate of PS release and the combining ability by using the heterosis to improve Fe utilizability of crop plants.