Phytosiderophore release from manganese-induced iron deficiency in barley

An experiment was conducted in the phytotron with barley (Horneum vulgare L. cv. Minorimugi) grown in nutrient solution to compare iron(Fe) deficiency caused by the lack of Fe with manganese (Mn)-induced Fe deficiency. Dark brown spots on older leaves and stems, and interveinal chlorosis on younger leaves were common symptoms of plants grown in either Mn-toxic or Fe-deficient treatments. Dry matter yield was affected similarly by Fe deficiency and Mn toxicity. The Mn toxicity significantly decreased the translocation of Fe from roots to shoots, caused root browning, and inhibited Fe absorption. The rate of Fe translocated from roots to shoots in the 25.0 mu M Mn (toxic) treatment was similar to the Fe-deficient treatment. Manganese toxicity, based on the release of phytosiderophore (PS) from roots, decreased from 25.0>250>2.50 mu M Mn. The highest release of PS from roots occurred 7 and 14 days after transplanting (DAT) to Mn-toxic and Fe-deficient treatments, respectively; but was always higher in the Fe-deficient treatment than the Mn-toxic treatments. The release of PS from roots decreased gradually with plant age and with severity of the Mn toxicity symptoms. The PS content in roots followed the PS release pattern.