Phloem translocation of Fe, Cu, Mn, and Zn in Ricinus seedlings in relation to the concentrations of nicotianamine, an endogenous chelator of divalent metal ions, in different seedling parts

Abstract

During the first 8 days of germination the Ricinus seedling is supplied with all nutrients by the endosperm via phloem transport. In 4-to 8-days-old seedlings the concentrations and contents of Fe, Cu, Mn and Zn, and nicotianamine (NA) in the endosperm, cotyledons, hypocotyl and roots were estimated. From the data obtained translocation rates and flow profiles for the metals were established. The main sink for Fe, Mn and Zn were the cotyledons whereas Cu was mainly imported into the hypocotyl. Maximum flow rates occurred between days 5 and 7, for Zn between days 6 and 8.The time kinetics of NA and divalent metal ion concentrations and contents are interpreted as co-transport. The role of NA as transport vehicle of micronutrients in the sieve tubes is discussed.Abbreviations: NA, nicotianamine

A Novel NAC Transcription Factor, IDEF2, That Recognizes the Iron Deficiency-responsive Element 2 Regulates the Genes Involved in Iron Homeostasis in Plants

“…NA, the precursor of MAs, is involved in translocation of metals not only in graminaceous plants but also in non-graminaceous plants (5,6,42,43). Several reports have described the abnormal distribution of iron in plants in the absence of NA or mutation of related transporters (6,(42)(43)(44)(45). The NA-free tomato mutant chloronerva shows interveinal chlorosis but overaccumulates iron in shoots and roots.…”

“…The NA-free tomato mutant chloronerva shows interveinal chlorosis but overaccumulates iron in shoots and roots. Because of a deficiency of NA in chloronerva, iron is not chelated by NA in soluble and available forms within the cells (43). Accordingly, the chloronerva mutant constitutively expresses genes involved in iron uptake and accumulates more iron in all tissues.…”

Assessment of Selected Heavy Metals in Onion Bulb and Onion Leaf (Allium cepa L.), in Selected Areas of Central Rift Valley of Oromia Region Ethiopia

“…Metal ions are also trans located from source to sink tissue via phloem. Therefore, phloem sap contains metals arising from source tissue, like Fe, Cu, Zn, and Mn [15].…”

Mutations in Arabidopsis Yellow Stripe-Like1 and Yellow Stripe-Like3 Reveal Their Roles in Metal Ion Homeostasis and Loading of Metal Ions in Seeds

“…Comparison to NA-Less Plants NA has been implicated as important for translocation of Cu, Fe, Mn, and Zn Stephan et al, 1994;Pich and Scholz, 1996). The roles of NA in plants have been deduced in large part by study of the tomato mutant chln, which cannot synthesize NA (Ling et al, 1999).…”