The control of cell shape and rate of cell expansion by ethylene: effects on microfibril orientation and cell wall extensibility in etiolated peas

Rapidly growing cells of etiolated Pisum sativum show two early responses to ethylene: a reduced rate of expansion and an increase in lateral growth. The latter has been explained in terms of an altered orientation of cellulose microfibrils in the cell walls: a change from transverse to longitudinal deposition is shown, using polarization microscopy, within 6 hours of exposure to ethylene. To explain the ethylene-induced reduction of growth rate, a plasmometric technique was used to study changes in the potential for plastic and elastic extension of cell walls and changes in cell turgor. Both wall extensibility and turgor were found to decline rapidly after exposing intact plants to 1 ppm ethylene and the significance of these changes in relation to ethylene control of cell growth is discussed.