Iron Induction of Ferritin Synthesis in Soybean Cell Suspensions

Abstract

In animal cells specialized for iron storage, iron-induced accumulation of ferritin is known to result from a shift of stored mRNA from the ribonucleoprotein fraction to polysomes. Previous reports with bean leaves suggested that in plants iron induction of ferritin synthesis would result from a regulation at the transcriptional level (F van der Mark, F Bienfait, H van der Ende cultures, the mechanism of regulation of ferritin synthesis in response to iron does not result from recruitment of preexisfing mRNA. They confirm that in plant systems, ferritin synthesis results from increased transcription of the corresponding genes.

Ferritin gene transcription is regulated by iron in soybean cell cultures.

“…Such is not the case: no ferritin mRNA was detected by hybridization (Fig. 2) or translation (30) in iron-depleted cultured soybean cells; similar results were obtained (29) when translatable ferritin mRNA in leaves from iron-deficient and iron-loaded bean plants was measured.…”

“…Iron increased the amount of translatable ferritin mRNA in bean leaves and in soybean cell cultures by =40-fold (29,30). To quantify the effect of iron on induction of ferritin mRNA and protein, total cellular RNAs of irontreated soybean cells were analyzed by electrophoresis and by hybridization.…”

“…Mandarin line Sbe4) were grown as described (32). Ferritin synthesis was induced by 500 IAM iron(III) citrate as described (30).…”

“…Earlier measurements of translatable ferritin mRNAs suggested that in contrast to animals, iron regulation may affect mRNA transcription rather than translation in bean leaves (29) and cultured soybean cells (30). Measurement of ferritin mRNA by translation in cellfree extracts could have been complicated by ferritin-mRNAspecific translational effects (13).…”

Iron Deficiency Induced by Chrysobactin in Saintpaulia Leaves Inoculated with Erwinia chrysanthemi

“…Soybean cells (Glycine max) were cultured in B5 medium as described previously (Proudhon et al, 1989) and inaintained in iron-free medium for 24 h before use. Equal aliquots of cell suspensiion were drained, and cells were suspencled in 2 mL of iron-free 85 medium inoculated with bacteria or supplemented with the aqueous siderophore solution to be tested.…”