Anatomical changes induced by two soil-borne pathogens (Plasmodiophora brassicae and Meloidogyne javanica) in cabbage

Abstract

Stunted growth of large patches of cabbage cv. Lupini, associated with severe soil infestations by the root-knot nematode Meloidogyne javanica and the protist Plasmodiophora brassicae, the casual agent of clubroot disease, was observed in several fields at Castellaneta, province of Taranto, in southern Italy. The host-parasite responses of cabbage roots to parasitism by the two soil-borne pathogens was studied and compared. In roots infected by P. brassicae, the plasmodia were present in cortex and pericycle cells, causing hypertrophy and hyperplasia, and developed into resting spores within host tissues. Parasitism of M. javanica was characterized by the establishment of distinct permanent feeding sites with giant cells in the cortex, endodermis and vascular parenchyma, which limit water and nutrient translocation.