TABLE CONTENTS

PCN: Dead or Alive, That is the Question
Den Nijs, L.J.M.F.
(1) National Reference Laboratory, Plant Protection Service, 15 Geertjesweg, P.O.Box 9102, 6700 HC
Wageningen, The Netherlands
PCN, or potato cyst nematodes (Globodera rostochiensis and G. pallida), are quarantine
organisms in the EU and due to this fact it is compulsory to sample the soil and find free of
PCN before growing propagation material. When cysts are found the contents of these cysts
are checked, as only live cysts form the basis for officially recording a field to be infested
with PCN. Hence the determination of juveniles being dead or alive is crucial. In most
countries the viability of cyst contents is determined visually by the microscope. In the
Netherlands a table describing visual characteristics is used in a attempt to standardize the
determination between laboratories. Proficiently tests however show that deciding whether
eggs and juveniles are dead or alive still causes much variability. To minimize the variability
between laboratories the table was extended with pictures and descriptions of characteristics
were adapted, based on comparative research and personal experience. The results of the
research and the proficiency test performed with the new extended table will be discussed. A
proposition is made to put forward the new table as an addition to the EPPO protocol of PCN.
Pathotypes of Globodera spp. as Detected by Superoxide Dismutase
Isoelectrofocusing Patterns
Molinari, S., (1), Greco, N. (1), Crozzoli, R., (2) & M. Zouhar (3)
(1) Institute of Plant Protection, National Research Council of Italy (C.N.R.), Via G. Amendola 122/D – 70126
Bari, Italy; (2) Universidad Central de Venezuela, Facultad de Agronomía, Post Grado en Zoología Agrícola,
Maracay, Venezuela; (3) Department of Plant Protection, Czech University of Life Sciences, Prague 6 Suchdol
165 21, Czech Republic.
Twelve populations of Globodera rostochiensis and 3 populations of G. pallida were
collected from different States of Venezuela, and different Chilean and Italian regions.
Standards of Ro1, Ro2, Ro3, Ro4, Ro5 pathotypes of G. rostochiensis, and of Pa2, Pa3
pathotypes of G. pallida were provided by the Czech University of Life Sciences in Prague.
About one hundred cysts of each population were used to extract proteins. Proteins were
separated according to their charge by isoelectrofocusing (IEF) on mini-gels inserted into the
automated Phast-System ® equipment. Gels were stained for superoxide dismutase (SOD)
activity. A high SOD polymorphism was found among the tested samples with the presence
of up to 12 enzyme activity main bands at different isoelectric point (pI range 8.7-4.4). By
means of a matrix built up on the presence/absence of these 12 bands, considered as
variables, a cluster analysis was carried out and a UPGMA dendogram was obtained. Groups
including populations of the 2 different species were well discerned by this analysis, as
predicted. Interestingly, the group including Ro1 standard was markedly distant from those
including all the other G. rostochiensis populations and standards. Ro2, Ro4, Ro5 standards
grouped together in a cluster different from that including Ro3. However, Ro2 belongs to a
subgroup which can still be differentiated from that to which Ro4 and Ro5 belong. The
provided standards of these latter pathotypes actually show almost identical IEF patterns.
Standards of Pa2 and Pa3 pathotypes were easily differentiated by this analysis. Also if this
method may be improved by using IEF patterns from other enzymes, this study indicates that
isozyme IEF phenotypes may be utilized to identify pathotypes or virulence groups of these
cyst nematodes in a manner easier, faster and more economic than that using the differential
Solanum clones.
5 th International Congress of Nematology, 2008 330