Histochemical alterations of various metabolites and their localization in Luffa cylindrica roots infected with Meloidogyne incognita

Experiment was carried out to study the alterations and histochemical localization of various metabolites in normal and galled roots of sponge gourd, Luffa cylindrica L., infected with root-knot nematode Meloidogyne incognita. Histochemistry of the roots revealed an increase in protein, nucleic acids (RNA and DNA) and amylodextrin (hydrolyzed starch) concentration in the infected regions as compared with normal healthy sections. Protein localization found more pronounced at the sites of infection of M. incognita viz., cortical cells, giant cells, abnormal xylem, medullary region and nematode body. Active RNA synthesis in infected cortical, medullary and vascular regions was observed by positively dark stained nucleoli, nucleoplasm and cytoplasm of their cells and syncytium. High DNA amount was observed in concentrate form in infected cells of cortex, pericycle and xylem tracheid of vascular region. Hyper hydrolysis of starch induced by M. incognita in sponge gourd roots was tested by studying the localization of amylodextrin. A positive test was observed with nematode body and surrounding tissues when stained with toluidine blue.