Induction of Fe(III)-Chelate Reductase Activity by Ethylene and Salicylic Acid in Iron-Deficient Peach Rootstock Explants

Abstract

The possible involvement of ethylene in the regulation of the root plasma-membrane Fe(III)-chelate reductase was investigated, using explants from three peach rootstock [GF-677 (Prunus amygdalus × P. persica), Cadaman (P. persica × P. davidiana) and Myrobolan 29C (Prunus cerasifera)] grown in Murashige and Skoog (MS) medium deprived of iron (Fe). Two ethylene inhibitors, AgNO₃ and salicylic acid (1, 10, and 20 μM), and two ethylene promotors, methionine and ethephon (1, 10, and 100 μM) were added in the culture medium. The AgNO₃ (20 μM) inhibited ethylene production, whereas salicylic acid (20 μM), methionine, and ethephon enhanced it. Explants cultured in the MS medium containing Fe (+Fe) produced less ethylene than those grown without Fe (−Fe). With the exception of the 100 μM ethephon-treated explants the increase in ethylene production was accompanied by an increase in root Fe(III)-chelate reductase activity. Conversely, exposure to AgNO₃ and salicylic acid (1 and 10 μM) had no effect on Fe(III)-chelate reductase activity of explants. Furthermore, Fe(III)-chelate reductase activity was higher in the (−Fe)-treated roots than in (+Fe)-treated ones. In most cases, the induction of Fe(III)-chelate reductase activity was accompanied by an increase in Fe, zinc (Zn), and phosphorus (P) concentration of explants. Chlorophyll concentration of explants exposed to ethylene decreased markedly. These results suggest that ethylene (and possibly salicylic acid) is involved in the regulation of Fe reduction in explants of peach trees.

keywords:

• ethylene
• Fe(III)-chelate reductase
• iron deficiency
• peach
• salicyclic acid

Notes

⁺Values in the same column followed by the same letter do not differ significantly at the 5% level, according to Duncan's multiple range test.

⁺⁺d.w. = dry weight.