Adventitious regeneration from tulip, lily and apple expiants at different oxygen levels

Abstract

Summary The effect of different O2 levels on regeneration of adventitious organs was examined in various systems, viz., shoot regeneration from tulip bulb scale and stalk explants, bulblet regeneration from lily scale expiants and root regeneration from apple stem slices. The expiants were exposed to 2 % O2 (low O2), 100 % O2 (high O2) or ambient air (20 % O2). Culture under continuous high O2 conditions had a moderate adverse effect in all systems. Continuous culture at a low level of O2 had strong inhibitory effects in tulip and apple, but was promotive in lily. When low O2 was applied only concurrent with the wound reaction, it had no or even an inhibitory effect (tulip stalks). High O2, applied directly after cutting apple stem slices, had a slight inhibitory effect on adventitious root formation. Once the regenerated organs had been formed, low O2 levels inhibited growth (in lily and tulip), and high O2 levels were stimulating in tulip and inhibitory in lily on organ growth. Our results show that the allegedly toxic effect of O2 is small or does not occur.