Agriculture Reference
In-Depth Information
Chapter 12
Role of Nematode-Trapping Fungi for Crop 
Improvement under Adverse Conditions
Rakesh Kumar Singh, Dipesh Kumar Trivedi and Amit Srivastava
1   Introduction
Nematodes are small round worms mostly found in all the natural habitats (soil,
aquatic and marine). A large number of nematodes are saprophytic free living and
feed on decaying plant and animal matter and sustain themselves by consuming
bacteria or other microscopic organisms. Some other nematodes are phytonema-
todes which are plant parasitic, attacking mainly the roots of the plants. More than
20 phytonematode species acting as obligate parasites of higher plants, have been
recorded and majority of them belong to the order Tylenchida . Phytonematodes that
cause biotic stresses are migratory ectoparasites, migratory endoparasites, semi-
endoparasites and sedentary endoparasites. These sedentary endoparasitic nema-
todes are characterized by their ability to produce specialized organs as feeding
cells within plant tissues, which mainly suppresses photosynthesis and process of
respiration in plant tissues (Schans 1991 ). These parasitic nematodes possess cer-
tain structural characteristics which ensure their existence in plant tissues. These
include the stylet adopted for penetration of plant cell walls and esophageal glands
and phasmids which discharge some enzymatic secretions into the root tissues that
help in the establishment of pathogenesis of nematode-induced plant diseases. Phy-
tonematodes create stress factors, to which plants respond in more or less the same
way as abiotic stress. The biotic stress induced by parasitic nematodes have several
characteristics distinguishing it from stress reactions caused by other pathogens.
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