International Journal of Food, Agriculture and Veterinary Sciences ISSN: 2277-209X (Online) An Online International Journal Available at http://www.cibtech.org/jfav.htm 2012 Vol. 2 (2) May-August, pp.147-154/Dubey and Trivedi Research Article 147 HISTOCHEMICAL LOCALIZATION OF CARBOHYDRATE IN HEALTHY AND MELOIDOGYNE INCOGNITA, INFECTED OKRA (ABELMOSCHUS ESCULENTUS (L.) MOENCH) *Widhi Dubey 1 and P.C. Trivedi 2 1 Deptt. of Botany/Biotechnology, Mahatma Gandhi Institute of Applied Sciences, Jaipur 2 Deptt. of Botany, University of Rajasthan, Jaipur *Author for Correspondence ABSTRACT Amongst the best known plant parasitic nematodes are the root knot nematodes, belonging to the genus Meloidogyne, which have a wide host range and are widely prevalent all over the world. These produce conspicuous galls on the roots and the infestations can be recognized easily in fields. It is very common and abundant in the sandy soils of Jaipur and adjoining areas. In Jaipur district, fields of okra an economically important vegetable crop were found infested with highly pathogenic Meloidogyne incognita. Histochemical tests were applied to localize total insoluble polysaccharides and cellulose in the diseased and healthy root tissues. Key Words: Meloidogyne Incognita, Histochemical Localization, Root Knot Nematode, Okra, Metabolites INTRODUCTION It is an accepted fact that pest including nematodes, can bring about disruption in the physiological equilibrium of the attacked plants. The plants, in turn, react in a number of ways to off-set these disturbances and the overall plant response determines, to a large extent, the success or failure of the interactions. For a better understanding of various histopathological changes that occurred as a result of nematode infection, in situ localization of various metabolites was helpful. Although, some pathogens used mechanical force to penetrate plant tissues but subsequent development of disease syndrome was dependent on histochemical alterations and biochemical reactions taking place between substances secreted by the pathogens and those already present or produced by the host as a response to the infection. Histochemical techniques were advantageous as they enabled in situ localization of various metabolites at the site of their synthesis or action. While information is available on morphological and biochemical changes that occur in plants invaded by endoparasitic nematodes, little work has been done with a histochemical technique. Since the anatomical area that is biochemically affected by such nematode infections may be quite small, it is imperative that histochemical techniques be employed, lest the effects of infection be lost by dilution from non-affected cells. After histochemically studying the soybean roots infected by Meloidogyne sp., it was reported that giant cell walls contained cellulose and pectin but lacked lignin, suberin, starch or ninhydrin positive substances (Dropkin and Nelson, 1960). It was observed that M. javanica induced giant cell in tomato contained traces of carbohydrates and fats but it was particularly rich in protein and RNA. The large irregularly shaped nuclei contained a large nucleolus and a number of feulgen-positive bodies, scattered irregularly along the nuclear envelope (Bird, 1961). It was reported that in ginger infected with root-knot nematode, giant cell nuclei and cytoplasm were rich in nucleic acids. Starch was absent in the giant cells and in the cells of the infected region of the rhizome. Giant cells showed the presence of minute protein granules. The outer side of the egg sac consisted of a thick layer of insoluble polysaccharides (Shah and Raju, 1977). The nucleic acid changes in three tomato cultivars infected with M. incognita were estimated, the observations showed that the amount of DNA and RNA was higher in roots of inoculated plants as compared to healthy ones in all the three cultivars (Masood and Saxena, 1980).