Studies On the Host-Parasite Relations of Pratylenchus Penetrans (Cobb) To Apple Seedlings

Abstract

A technique is described for the inoculation, under aseptic conditions, of apple seedlings with the root lesion nematode Pratylenchus penetrans (Cobb, 1917) Filip. & Stek., 1941. Under these conditions apple feeder roots (i.e. those without secondary thickening) react to nematode invasion by a rapid discolouration of the outermost, (i.e. epidermis and hypodermis) and innermost, (i.e. inner cortex and endodermis) cortical tissues, but show little or no reaction in the intervening cortical parenchyma. This response is compared with that of peach roots, in which all the cortical tissues are readily discoloured by this nematode. Histochemical tests suggest that sensitivity to P. penetrans is correlated with the presence and concentration of phenolic substances in the various tissues of these two hosts.