UC Riverside

Evolutionary relationships based on nucleotide variation within the D3 26S rDNA region were examined among a collection of seven Meloidogyne hapla isolates and seven isolates of M. arenaria, M. incognita, and M. javanica. Using D3A and D3B primers, a 350-bp region was PCR amplified front genomic DNA and double-stranded nucleotide sequence obtained. Phylogenetic analyses using three independent clustering methods all provided support for a division between the automictic M. hapla and the apomictic M. arenaria, M. incognita, and M. javanica. A nucleotide sequence character distinguishing M. hapla from the three apomictic species was a 3-bp insertion within the interior of the D3 region. The three apomictic species shared a common D3 haplotype, suggesting a recent branching. Single M. hapla individuals contained two different haplotypes, differentiated by a Sau3AI restriction site polymorphism. Isolates of M. Javanica appeared to have only one haplotype, while M. incognita and M. arenaria maintained more than one haplotype in air isolate.