Identification of Meloidogyne incognita, M-javanica and M-Arenaria using sequence characterised amplified region (SCAR) based PCR assays

Three randomly amplified polymorphic DNA (RAPD) markers, OPA-12(420). OPB-0 6(1200) and OPA-01(700), species specific to the root-knot nematode species Meloidogyne arenaria, M. incognita and M. javanica respectively, were iden tified. After sequencing these RAPD-PCR products. longer primers of 18 to 2 3 nucleotides were designed to complement the terminal DNA sequences of the DNA fragments. This resulted in three pairs of species specific primers th at were used to amplify the sequence characterised amplified regions (SCARs ). The developed sets of SCAR primers were successfully used in straightfor ward, fast and reliable PCR assays to identify M. incognita. M. javanica an d M, arenaria. The length variant SCAR markers can be amplified from DNA fr om egg masses, second stage juveniles and females. This species identificat ion technique is therefore independent of the nematode's life cycle stage. Moreover the SCAR-PCR assay was successfully applied using DNA extracts fro m infested plant material. The method has potential to be optimised for rou tine practical diagnostic tests facilitating the control of these economica lly important pest organisms.