Laticifer Differentiation in Hevea brasiliensis: Induction by Exogenous Jasmonic Acid and Linolenic Acid

Laticifer differentiation of Hevea brasiliensis was investigated by application of lanolin containing jasmonic acid (JA) or other chemicals to the surface of young stems in epicormic shoots. The young stems had primary laticifers and no secondary laticifers. When applied to extending young stems, JA led to a significant increase in primary laticifer number but did not induce secondary laticifer differentiation. Secondary laticifer differentiation and a less significant increase in primary laticifer number were caused by JA application to the extended young stems. The induction of the secondary laticifers was dependent on the concentration of JA applied. Cambium cell division leading to the formation of secondary phloem was not accelerated by JA treatment. Treated bark tissues showed no visible changes except for the additional laticifers, which were normal in ultrastructure. The secondary laticifers were also induced by the application of linolenic acid, a precursor of JA biosynthesis. Abscisic acid, ethephon and salicylic acid had no detectable effect on laticifer differentiation. Copyright 2000 Annals of Botany Company