Annals of Plant Protection Sciences

In a study, isozyme and DNA polymorphisms were used to characterize some economically important species of cyst nematodes encountered on graminaceous and leguminous hosts in India. Isozyme analysis by polyacrylamide gel electrophoresis (PAGE) revealed distinctive and unique esterase (Est) and malate dehydrogenase (Mdh) profiles in Heterodera avenae, H. eajani, H. sorghi and H. zeae. Two esterase phenotypes were found in H. avenae and, H. zeae and 3 in H. eajani and H. sorghi. Although Mdh pattern was monomorphic, it could differentiate the four species by the Rm values. The DNA polymorphism was easily discriminated all the four species of Heterodera by differences in random amplified polymorphic DNA (RAPD) fragments. Two to seven fragments of size 500–1100 base pairs distinguished all the cyst nematode species by each of the six selected primers with primer 3 yielding the simplest, yet clear species-specific diagnostic bands. Two simple sequence repeat (SSR) primers (CAG)s and (AGG)s could also easily distinguish four test species of Heterodera. Both isozyme and DNA markers proved to be species-specific probes for applications in quick diagnosis.