Heavy-metal-induced ethylene production in Arabidopsis thaliana

Different plant parts varied in copper sulfate (CuSO4) and cadmium sulfate (CdSO4)-induced ethylene production, inflorescences showed the greatest induction, while all other plant parts tested produced significantly less. Leaf age had a dramatic effect on CuSO4 and CdSO4-induced ethylene production with the youngest leaves showing the greatest stimulation and as the age of the leaf increased there was a reduction in their ability to produce ethylene. However, there was no significant difference in CuSO4, CdSO4 and wound-induced ethylene production when whole rosettes were taken from plants that were 7, 14 or 21-day-old. The highest amount Of CuSO4 and CdSO4-induced ethylene production was produced in the root tip with regions below this producing less. CuSO4 and CdSO4-induced ethylene production was also greatest from the tip of the inflorescence to 2cm below the tip and from this point down there was a reduction in ethylene production. When inflorescence stalks or leaves were treated with CuSO4 or CdSO4 over a range of concentrations from 0 to 800 mu M, there was an increase in ethylene production starting at 50 M with increasingly greater responses up to 400 mu M. There was no further increase at the 800 mu M CuSO4 concentration; however, there was a slight decline with 800 PM CdSO4. Inflorescence stalks or Leaves treated with either 400 mu M CuSO4 or CdSO4 exhibited a dramatic increase in ethylene production 2h following treatment initiation and remained high over a 24-h period with a decline in ethylene production after this time in inflorescence stalks but not the leaves. It was found that light caused a dramatic decrease in CuSO4, CdSO4 and wound-induced ethylene production in both inflorescence stalks and leaves. When inflorescence stalks or Leaves were treated at 43 degrees C, there was a dramatic effect on CuSO4, CdSO4 and wound-induced ethylene production in each. (C) 2006 Elsevier GmbH. ALL rights reserved.