TABLE CONTENTS

Anatomical and Histological Alterations Induced by a Species of Plantparasitic
Nematode of the Genus Hemicycliophora in Celery (Apium
graveolens) Roots from Argentina
Challier, E. (1), M. del C. Tordable (1), S.A. Suárez (1) & M.E. Doucet (2)
(1) Departamento de Ciencias Naturales, Universidad Nacional de Río Cuarto, Río Cuarto 5800, Argentina. (2)
Centro de Zoología Aplicada, Universidad Nacional de Córdoba, Córdoba 5000, Argentina.
In order to characterize the anatomic and histological alterations in roots of celery (Apium
graveolens) produced by the presence of a species of the genera Hemicycliophora, we
evaluated the host-nematode relationship through exomorphological, anatomical and
histological analyses. Plants grew in soil obtained from Pucará, Aconquija, Department of
Andalgalá, province of Catamarca. Samples of both infected and healthy roots were
processed for optical microscopy. The infected roots showed galls of different characteristics:
small, simple galls with cylindrical shape, and larger, complex galls, with various shapes. On
the surface of both types of galls, nematode specimens could be observed. It could also be
observed that the small galls showed cellular hyperplasia affecting the pericycle which
produced prominences of meristematic tissue. These prominences formed primordia of lateral
roots. The vascular tissues were disorganized and displaced. In the complex galls the
histological changes were similar to those observed for the simple galls. However, the
complex galls were formed by numerous differentiated lateral roots, some of which were also
modified, producing simple galls. The central body of complex galls was constituted by adult
tissues. The changes induced by the nematode were associated to the presence of galls with
an important proliferation of lateral roots. Their histological characteristics suggest that the
simple galls represented a stage previous to their development into complex galls and the
alterations of their vascular tissues probably affected their functionality.
Host-finding in Potato Cyst Nematodes
Farnier, K., N. Punyasiri, M. Bengtsson, P. Witzgall & S. Manduric
SLU - Swedish University of Agricultural Sciences. Department of Plant Protection Biology, Box 102, 230 53
Sweden
Potato cyst nematodes, Globodera rostochiensis and G. pallida are stimulated to hatch from
cysts within the second and fifth week after potatoes start to produce roots. Lipid reserves of
potato cyst nematodes allow them to survive during ca. ten days in their search of a suitable
host plant. We hypothesize that potato roots release chemicals that guide newly hatched
nematodes to roots. The aim of this study is to identify the chemical cues and behavioural
mechanisms that allow potato cyst nematodes to recognize and localize their host.
Attraction of nematodes to potato roots and root exudates is investigated in an agar-plate and
a glass-tube bioassay. Nematode behaviour during different phases of the host-seeking
process is described. Root exudates are obtained from potatoes grown in sand, in hydroponic
and aeroponic systems. The hatching and attraction response of nematodes to roots, root
exudates and fractions of root exudates from a susceptible potato variety are studied using
these bioassays. In addition, first results of the chemical analysis of active exudates by GC-
MS, HPLC-DAD, HPLC-MS are presented.
5 th International Congress of Nematology, 2008 203