Histopathogenesis of Galls Induced by Meloidogyne naasi in Wheat Roots


  • I. A. Siddiqui
  • D. P. Taylor


Histopathogenesis of galls induced by Meloidogyne naasi in wheat roots was studied. Large numbers of larvae penetrated wheat root tips within 24 hr; larvae migrated both inter- and intracellularly, causing cortical hypertrophy. Giant cells were formed in the stele around the head of each nematode within 4 to 5 days. Initial pathological alterations in giant cell formation consisted of hypertrophy of protophloem and protoxylem cells, their nuclei and nucleoli. Giant ceils contained 2 to 8 agglomerated multinucleolate nuclei. Synchronous mitotic divisions were first observed 9 days after inoculation. After 21 days, giant cells became highly vacuolate. Observations 40 days after inoculation revealed a complete degeneration of cell contents in many giant cells but their thick walls remained intact. Abnormal xylem completely surrounded the degenerated or partially degenerated giant cells. Key Words: Meloidogyne naasi, Barley root-knot nematode, Histology, Cytology, Pathogenesis, Host-parasite relationships, Galls, Wheat.