why some plant cultivars are susceptible and some are resistant to plant parasitic nematodes? which mechanisms can make plant resistance and what is its geneticsl base?
Since chitin is the essential component of nematode eggshell and pharynx, one may infer that nematode-resistant plant cultivars show chitinase genes in their genome.
Reading this scientific publication may help you understand this important resistance mechanism.
Here is the web link.
Activity and Differential Induction of Chitinase Isozymes in Soybean Cultivars Resistant or Susceptible to Root-knot Nematodes - PMC (nih.gov)
Here are the data pertaining to this publication.
J Nematol. 1997 Dec; 29(4): 523–530.
Activity and Differential Induction of Chitinase Isozymes in Soybean Cultivars Resistant or Susceptible to Root-knot Nematodes
There exist other nematode resistance genes in plants than chitinase genes.
A comprehensive genomic analysis of nematode resistance in plants is described in this scientific publication.
Here is the web link.
Frontiers | Plant Genetic Background Increasing the Efficiency and Durability of Major Resistance Genes to Root-knot Nematodes Can Be Resolved into a Few Resistance QTLs (frontiersin.org)
Here are the data for this publication.
Front. Plant Sci., 10 May 2016 Sec. Plant Breeding Volume 7 - 2016 | https://doi.org/10.3389/fpls.2016.00632
Plant Genetic Background Increasing the Efficiency and Durability of Major Resistance Genes to Root-knot Nematodes Can Be Resolved into a Few Resistance QTLs