Ethylene-induced activation of xylanase in adventitious roots of maize as a response to the stress effect of root submersion

Submersion of roots of ten-day-old maize (Zea mays L.) seedlings was accompanied by a decrease in pO(2) and an increase in pCO(2) of the medium adjacent to the roots. These changes stimulated ethylene evolution in intact plants. Enhanced biosynthesis of ethylene was accompanied by xylanase activation in adventitious roots. As a result, an enhanced formation of aerenchyma was observed in the cortex of adventitious roots. Therefore, these processes resulted in the development of a ventilation system by which O-2 can reach the root system exposed to hypoxia. The volume of aerenchyma was assessed by the volume of gas cavities (porosity). In contrast to the main root, the growth of adventitious roots was not inhibited under these conditions. Enlargement of the stem base and increase in the number of aerenchymatous adventitious roots facilitated the oxygen supply to the submerged organs of the plants.