بررسي هيستوپاتولوژي در دو گونه نارون اوجا و ملج مايه زني شده با قارچ Ophiostoma novo-ulmi

A survey on histopathology of Ulmus glabra and U. carpinifolia inoculated by Ophiostoma novo-ulmi fungus

Dutch elm disease is one of the most important vascular diseases of elm. However, it has always being considered to survey its different perspectives such as; distribution, biology, pathogencity, histopathology, disease management and ctc. In order to investigate host-pathogen interaction, this research was carried out with title survey on histopathology of two elm species, Ulmus glabra and U. carpinifolia inoculated by Ophiostoma novo-ulmi the causal agent of Dutch elm disease. When withered and dieback symptoms were occurred 4-8 weeks after inoculation by Ophiostoman novo-ulmi against seedlings, transversal sections were prepared from lower parts of withered and dried foliage. Then, very thin transversal sections were prepared and after different stages of staining, microscopic slides were prepared. The results of microscopic investigations showed that the causal agent of Dutch elm disease has caused disordered in physiology and flowing of vascular sap through spreading into vessels, obstruction of xylem vessels and their destruction. The results also showed that seedlings with tylose production caused obstruction of vessels and prevented spreading of pathogen. Pathogencity and defensive mechanisms associated with host-pathogen interaction and their roles at susceptibility rate of Ulmus carpinifolia and U. glabra to Dutch elm disease was discussed in this paper.