ITS polymorphism and taxonomy/phylogeny

Byron Adams bjadams at biocomp.unl.edu
Wed Dec 3 19:50:17 EST 1997

>We are working on phytopathogenic enterobacteriaceae: the
>pectinolytic erwinias and presently particularly on the pathovars
>of Erwinia chrysanthemi.
>We observe a size polymorphism, when we amplify by PCR the ITS
>located between the 16 and 23S subunits of the rRNA.
>Does anybody know references about such a polymorphism between
>species but also more particularly between strains of a species?
>Has such a polymorphism been correlated to infra-species divisions?
>Thanking you in advance for your help.
>		Yves Bertheau
>		Pathologie vegetale
>		INRA, Paris, FRANCE

Hello Yves -

	My work with ITS sequences is limited to nematodes, but for what
it's worth, we have looked at the ITS regions (between the 18S and 26S
subunits) of many nematode taxa and sometimes find size polymorphisms
between species, and occasionally between "presumed closely related" (read:
morphologically similar) species, but have yet to see it within species.
We have, however, uncovered sequence polymorphisms within individuals.  I
have observed "infra-species" (in this case among populations) differences
at the nucleic acid level, but have not observed "infra-specific" ITS size
variation.  The use of the ITS as a taxonomic marker for nematodes is the
topic of a paper due out soon in the December issue of the Journal of

Powers, T. O., T. C. Todd, A. M. Burnell, P. C. B. Murray, C. C. Fleming,
A. L. Szalanski, B. J. Adams, and T. S. Harris.  1997.  The rDNA internal
transribed spacer region as a taxonomic marker for nematodes.  Journal of
Nematology 29(4)


Byron J. Adams
Department of Plant Pathology
406 Plant Sciences Hall
P.O. Box 830722
Lincoln, NE 68583-0722
lab (402) 472 5598
fax (402) 472-2853

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