Relationship of Different Species of Heterodera with Taxonomic Grouping of Host Plants

Studies on the affiliation of 62 species of Heterodera to taxonomic groups of host plants revealed that thirty heteroderids parasitized only monocotyledons and out of these 17 were monophagous. Thirteen species showed monophagy in dicotyledons. Heteroderid groups (clades) revealed that Avenae and Sacchari groups intimately affiliated with monocots and perhaps co-evolved with them. Sacchari group do not feed on dicots. Schachtii group co-evolved with dicots. Humuli group was associated with plants of wide taxonomic range. Cyperi group parasitized plants largely from monocots and species from Goettingiana group feed on plants of both dicots and monocots. The species affiliation with monocots was not restricted at family level but continued up to subfamily and tribe levels. Strong relationships in dicots was noticed with Fabaceae, Brassicaceae and Chenopodiaceae. Races of some species of Heterodera showed close association with certain genera.