| Abstract: | We have assessed the effect of various medium supplements inpromoting the ability of maize (Zea mays L.) inbred FR27rhmsuspension cultures to grow following a period of 4 °C chillingstress. Following a 4 week exposure to 4 °C in culture mediumwithout proline, no cell growth occurred upon subsequent incubationat 28°C for 2 weeks. This inhibition was reversed when 3to 48 mol m–3 proline or 0.1 mol m–3 putrescineor 0.01 mol m–3 spermidine were present in the mediumduring the chilling stress. On the other hand, suspensions weremade more sensitive to 4°C by blocking polyamine biosynthesiswith 1.0 mol m–3 methylglyoxal bis (guanylhydrazone) (MGBG)or a combination of 1.0 mol m–3 difluoromethylornithine(DFMO) and 1.0 mol m–3 difluoromethylarginine (DFMA).The addition of 10 mol m–3 putrescine to the suspensioncontaining DFMO and DFMA prevented the increased chilling sensitivity.Electrolyte leakage studies conducted to assess membrane integrityafter 4 weeks at 4°C and a 2 week regrowth period showedthat cells treated with no polyamines (control), 0.01 mol m–3spermidine, 1.0 mol m–3 putrescine, or 1.0 mol m–3MGBG lost 43, 32, 14, and 100% of the total electrolyte pool,respectively. These results suggest that proline and polyaminesare beneficial for inducing chilling tolerance in FR27rhm suspension. Key words: Proline, polyamine, chilling stress |
