Visualizing real time [11C]methionine translocation in Fe-sufficient and Fe-deficient barley using a Positron Emitting Tracer Imaging System (PETIS)

[C-11]methionine was supplied to Fe-deficient and re-sufficient barley plants through a single leaf, and real time C-11 movement was monitored using a Positron Emitting Tracer Imaging System (PETIS), In Fe-deficient plants, [C-11]methionine was translocated from the tip of the absorbing leaf to the 'discrimination centre' located at the base of the shoot, and then retranslocated to all the chlorotic leaves within 60 min, while a negligible amount was retranslocated to the roots, In re-sufficient plants, methionine was translocated to the discrimination centre and then only to the newest leaf on the main shoot within 60 min. A negligible amount was also retranslocated to the roots. In conclusion, methionine from the above-ground parts of a plant is not a precursor of mugineic acid under re-deficiency. The discrimination centre is suggested to play a vital role in the distribution of mineral elements and metabolites in graminaceous monocots.