In vivo staining of reduced iron by 2,2′ bipyridine in rice exposed to iron toxicity

A protocol for a novel method to visualize Fe(II) in rice tissues is proposed. The method is based on the selective formation of a purple‐red color complex of 2,2′ bipyridine and Fe(II). Rice genotypes were exposed to 18 mM Fe(II) in nutrient solution for 2 d. Root systems of intact plants were subsequently placed in 2,2′ bipyridine solutions. The formation of the [Fe(bipy)<$>_3^{2+}<$>] color complex was visualized using bifocal microscopy. The method may improve the selection of genotypes during breeding for Fe‐toxicity resistance of rice.