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

Laticifer differentiation of Hevea brasiliensis was investigatedby application of lanolin containing jasmonic acid (JA) or otherchemicals 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 significantincrease in primary laticifer number but did not induce secondarylaticifer differentiation. Secondary laticifer differentiationand a less significant increase in primary laticifer numberwere caused by JA application to the extended young stems. Theinduction of the secondary laticifers was dependent on the concentrationof JA applied. Cambium cell division leading to the formationof secondary phloem was not accelerated by JA treatment. Treatedbark tissues showed no visible changes except for the additionallaticifers, which were normal in ultrastructure. The secondarylaticifers were also induced by the application of linolenicacid, a precursor of JA biosynthesis. Abscisic acid, ethephonand salicylic acid had no detectable effect on laticifer differentiation.Copyright 2000 Annals of Botany Company Hevea brasiliensis, laticifer differentiation, jasmonic acid, linolenic acid, vascular cambium.