Immunohistochemical localization of IAA in graft union of explanted internode grafting

The dynamic changes of IAA in graft union of explanted internode autografti ng of Cucumber (Cucumis sativus Linn.) have been investigated using the imm unohistochemical localization technique. It is shown that the efficiency of IAA fixation using lyophilization-gas fixation is higher than that using l iquid chemical fixation. In contrast to few sliver particles and no signifi cant changes during the development of graft union cultured in hormone-free medium, more silver particles in graft union and significant changes of IA A related to graft union development have been found when graft union was c ultured in medium supplemented with appropriate hormones. The fixation proc edure of plant hormones and the roles of IAA in graft union are discussed.