Comparative Root Morpho-Anatomical Studies On Meloidogyne Graminicola Resistant And Susceptible Rice Genotypes

Abstract

The work characterizes root morpho-anatomical changes in rice due to infestation of rice root-knot nematode, Meloidogyne graminicola. The susceptible rice genotype, Satabdi (IET-4786) and resistant rice genotypes Marichsal and Lakshmansal were inoculated with three different geographic isolates of M. graminicola viz., Mg1 (Ashui, West Medinipur), Mg2 (Sumitrapur, West Medinipur) and Mg3 (Gayeshpur, Nadia). The results of demonstrated that, transverse section of morpho-anatomical structure of Mg1 isolate inoculated root at 25 DAI to susceptible and resistant rice genotypes viz., Satabdi and Marichsal showed presence of adult females and egg-mass in the cortex which symbolized a successful host parasitic relationship. Organization of cellular architecture of adventitious root of rice genotypes Satabdi and Marichsal when inoculated with Mg2 isolate then nematode infestation led to drastic changes as evidenced by the disorganization of cortical cells along with dissolution of epidermal, exodermal and sclerenchymatous cells at 10 DAI. The rice genotype, Lakshmansal did not reveal any changes in the root morpho-anatomy when inoculated with Mg2 isolate at 10 DAI. The cross section of the roots of Satabdi and Marichsal revealed complete obliteration of root anatomical structures along with formation of multinucleate giant cells, cavities in the stele owing to nematode injury along with females and egg-masses at 10 and 25 DAI of Mg3 isolate. The rice genotype Lakshmansal, was characterized as resistant against all three isolates of Mg as confirmed by histological study of roots. Cortical thickness of uninfected rice roots was comparatively lesser than infected ones, while maximum stele diameter was recorded with Marichsal when inoculated with Mg1 isolate i.e. 523.01 µm at 25 DAI. Outer portion of the root was also less than infected ones. Giant cell diameter of Satabdi and Marichsal ranged from 43.45-107.46 µm and 30.68-102.67 µm, respectively, indicating successful establishment of host-nematode interaction.