Histopathological comparison of galls induced by Anguina tritici with galls subsequently colonised by Rathayibacter tritici in wheat

Abstract

Histopathological differences between seed galls of wheat cv. Mexipak containing only the nematode Anguina tritici and those also colonised by the bacterium Rathayibacter tritici are described. At early stages of gall development, nematodes were present in both types of gall and the cells forming the galls appeared structurally normal with prominent nuclei. After further development, marked differences between nematode- and bacterially-colonised galls were observed. Bacterially-colonised galls contained a pore through which bacterial cells and gummosis exude. Pores were not observed in normal nematode galls. Normal galls had clear organisation with wide walls, and enlargement and thickening of the cell walls of the outermost cell layer. Whereas bacterial galls had loose cellular structure, with bacteria abundant in gall cavities; in most cases nematodes could no longer be seen. The bacteria were never observed in galls containing eggs or second stage juveniles of the nematode.