Worm Breeder's Gazette 9(3): 66
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
Plant parasitic Meloidogyne races can be distinguished by differences in banding patterns of repetitive DNA sequences observed from ethidium bromide stained gels of genomic restriction digests ( Curran, J. et. al., J. Nematology 18: 83, 1986). Some of the repeat sequences homologous to C. 8s, 5.8s, and 26s) and 5S DNA. Surprisingly, a C. robe hybridized to the rDNA bands in M. arenaria (race B) and M. hapla (race B). In M. arenaria, two size classes of repeats, 5kb and 9kb, have been cloned into pUC 13. The two repeats have similar restriction sites at the ends which could suggest common origin. Moreover, we have observed a faint ladder of bands below restriction fragments from the center of the 9kb repeat. This could represent deletions caused by recombinational events in repetitive DNA, and might mimic the processes by which the two classes evolved. Regions homologous to C. S, 265 and 5S DNA have been localized (see map). An 800bp region in the 5kb repeat contains a sequence >85% homologous to the C. DNA, but has no apparent pol III terminator, and is inactive in a C. ption extract. We are currently looking further at the expression of the rDNA and 5S DNA, and its organization in the related M. hapla. For the latter, six different recombinant EMBL phage carrying both 55 DNA and rDNA are being analyzed.