TABLE CONTENTS

SESSION THIRTY-ONE – MOLECULAR AND APPLIED SYSTEMATICS
AND TAXONOMY
CONVENORS: ALEX HOLOVACHOV & MANUEL MUNDO-OCAMPO
Molecular Systematics of the Order Tylenchida: From Ribosomal RNA
Genes to Genome Analysis
Subbotin, S.A. (1,2), B. Adams (3), W. Bert (4), P. Castillo (5), V.N. Chizhov (6),
R.N. Inserra (7), T. Powers (8), D. Sturhan (9), E. Van Den Berg (10), N. Vovlas (11),
W. Ye (12), G. Yeates (13) & J.G. Baldwin (2)
(1) California Department of Food and Agriculture, USA; (2) University of California, Riverside, USA; (3)
Brigham Young University, USA; (4) Ghent University, Belgium; (5) Institute of Sustainable Agriculture,
Spain; (6) Center of Parasitology, Russia; (7) Florida Department of Agriculture and Consumer Services, USA;
(8) University of Nebraska; (9) Arnethstr. 13D, 48159 Münster, Germany; (10) Plant Protection Research
Institute, South Africa; (11) Istituto per la Protezione delle Piante, Italy; (12) North Carolina Department of
Agriculture and Consumer Services, USA; (13) Landcare Research, New Zealand.
The order Tylenchida (sensu Siddiqi, 2000) includes the largest and most economically
important nematode parasites of plants, insects and mites, as well as mycophagous species.
The wide range of taxonomic problems, from the level of species to suborder, using classical
morphological analysis, is well known. Many of these problems have been addressed and
solved by molecular analysis and new insight in to phenotypic evolution. These molecular
approaches, taking into account ribosomal genes (D2-D3 of 28S rRNA, 18S rRNA and ITSrRNA),
are reviewed. The importance of the congruence of extant morphologically and
biologically-based tylenchid classifications with molecular phylogenies, and tests of
monophyly of some superfamilies, families and genera is emphasized. Hypotheses
concerning the ancestral form of tylenchids and origins of specialized sedentary parasitism
also have been tested with these molecular approaches. Several examples of estimating
species boundaries for plant parasitic nematodes using molecular methods are given. It
appears that multiple gene sequence and phylogenetic analysis could provide a rigorous
system to critically examine species boundaries originally proposed on traditional
morphological/taxonomic approaches. The forthcoming results of the genomic projects for
tylenchids will have a profound impact on inquiries at all taxonomic levels, providing better
tools for estimating phylogeny and population structure and ultimately for allowing the
identification of genes and mechanisms which regulate the evolution of plant parasitism.
5 th International Congress of Nematology, 2008 113