Page 259 - e-Book

morphological response to infection by Meloidogyne spp. These cells would provide as a

concentrated supply of protein for the nematode's growth. Plan-parasitic nematodes are well-
known enemies of crop yields in the agricultural sector. Plant-parasitic nematodes are thought

to be responsible for ten percent of global crop output loss, accounting for one-third of the
overall loss ascribed to pests and diseases (White head, 1998). Meloidogyne incognita, a plant

parasitic nematode, is an obligate endoparasite that causes significant damage to
economically important crops around the world (Khan et al., 2004; Gogoi and Neog, 2003).

Root-knot nematode causes (a) a wide range of morphological and anatomical

responses in different plants, as well as in different areas of the same plant, and (b) different
species can induce diverse reactions in the same plant (Krusberg, 1963). In addition, when

large cells and galls form, alterations in plant physiology contribute to restricted growth.

Tissues degrade in the sick state, development and reproduction are hampered, and water is
scarce due to altered biochemical contents. All of these research have demonstrated that the

pathological state has its own biochemistry. It is argued (Roy, 1980) that one can assess the
host-parasite interaction by determining these biochemical changes during infection, as it is

clear that the extent of harm to the host and the parasite's development are primarily
dependent on these biochemical changes. Neal recognised the pathogenicity of the root-knot

nematode as early as 1889. The initial step in establishing host parasite connection is

penetration of the second stage juveniles (I2) root-knot nematode Meloidogyne spp at the
zone of elongation. It infects plant roots as a result of a stimulation from the roots (Green,

1971and Prot, 1980).
Root exudates comprising sugars, amino acids, electrolytes, and other nutrients

impact egg hatching and positive taxis toward root tip growth (Bird, 1959). Various
researchers have looked into the nature of the nematode's penetration into the host plant

(Patel,1991;Siddiqui,1998). Stunting is frequently linked to root tissue injury. Damage to the

cortical system (Sujatha and Metha, 1998), as well as damage to the cells' xylem and phloem,
causes the decreased roots to grow this way (Sundararaju and Mwhata, 1992). In addition, the

weight of the plant's root and branches has decreased, resulting in slower development

(Panday et al., 1992; Haseeb et al., 1993). The loss of root efficiency, as well as a portion of
the resulting drop in growth and yield, can be attributed to the root system's decrease and

deformation.
During pathogenesis, the nutritional stress exerted on the host is alleviated by changes

in the biochemical components of the infected tissues. Infected plants showed signs of sugar
depletion (Mohan and Dhawan, 2000; Vaithesswaran and Mohamed Ibrahim, 2003). Sugar

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