a-Amylase expression under anoxia in rice seedlings: an update

Rice grains can germinate under anoxia, while most other cereals fail to behave similarly. The ability of rice grains to degrade starch, thanks to the successful production of a-amylase even in the absence of oxygen is likely one of the factors allowing rice to germinate anaerobically. In this paper we review the most recent results obtained about the physiology and molecular biology related to the expression of a-amylase genes under anoxia. The current view is that expression of sugar-starvation induced isoforms of a-amylase play a major role during germination under anoxia, while gibberellin induced a-amylase predominates under aerobic conditions.