Peptides related to phytosiderophore secretion by Fe‐deficient barley roots

Abstract

The peptides appearing in barley roots related to phytosiderophore synthesis or absorption under Fe‐deficiency were analyzed. Two varieties of barley were used. ‘Ehimehadaka NO.1¹ secreted 3‐epihydroxymugineic acid and traces of 3‐hydroxymugineic acid, mugineic acid and 2'‐deoxymugineic acid. ‘Minorimugi’ secreted mugineic acid, and traces of 3‐epihydroxymugineic acid and 2'‐deoxymugineic acid. Peptides in supernatant fractions of Fe‐deficient roots were detected by ³⁵s‐fluorography and/or by silver‐stain on two dimensional electrophoresis. In the case of ‘Ehimehadaka NO.1’, two peptides (m.w. 53kD, pI 6.6) and (53kD, 6.7) by fluorography, and (52kD, 6.9), (31kD, 6.6) and (30kD, 6.8) by silver‐stain were detected. In the case of ‘Minorimugi’, two peptides (53kD, 6.6) and (53kD, 6.7) by fluorography, (31kD, 6.6) and (30kD, 6.8) by silver‐stain were detected. The synthesis of the 53kD peptide was strongly related to the secretion amount of phytosiderophores. Whereas the 52kD related to 3‐epihydroxymugineic acid synthesis. The 31kD and 30kD may be peptides related to the absorption mechanism of Fe^III‐phytosiderophore chelate by the roots.