TABLE CONTENTS

Antagonistic Activity of an Isolate of Pochonia chlamydosporia var.
chlamydosporia on Root-knot Nematode in vitro
Ebadi, M. (1), S. Fatemy (2) & H. Riahi (1)
(1) Biology Department, University of Shahid Beheshti, P. O. Box 19839, Tehran, Iran; (2) Nematology
Department, Plant Protection Research Institute, P. O. Box 1454-19395, Tehran, Iran.
In this study, antagonistic activity of an isolate of Pochonia chlamydosporia
var.chlamydosporia was examined on Meloidiogyne javanica. Fungus was cultured on PDA
and rate of colony growth per day were measured at different temperatures after 10 days at
dark. Center of Petri-dishes containing 0.8 % water agar and antibiotics were inoculated with
plugs of infected CMA with fungus, sterilized egg masses of nematodes were placed near the
center and plates including control without fungus were arranged randomly in an incubator at
18 ○ C at dark for 3 weeks. Culture filtrate was obtained by growing fungus on 1.5% malt
extract broth for 2 weeks at 22 ○ C, contents including uninfected medium were filtered; 1 ml
of extracts were placed in a well of tissue culture plate, 50 J2 were added to each well and
plates with 9 replicates kept at 13 ○ C. Maximum growth rate occurred between 25-28 ○ C; only
5% of the juveniles were immobilized in full culture filtrate after 48 h; and approximately
more than 80% of the eggs were colonized by the fungus on water agar.
Gene Expression Profiles in Pochonia chlamydosporia in Conditions of
Saprotrophic-to-parasitic Transition
Finetti-Sialer, M. (1), P. Hirsch (2), B. Kerry (2) & I. Clark (2)
(1) CNR, Istituto di Genetica Vegetale, Via G. Amendola 165/A, 70126, Bari, Italy (2) Nematode Interaction
Unit, IACR-Rothamsted, Harpenden, Herts AL5 2JQ, UK.
Biotypes of Pochonia chlamydosporia play an important role as biological control agents of
root-knot and cyst nematodes in the plant rhizosphere. A better understanding of the
biochemical mechanisms involved in P. chlamydosporia saprotroph-to-parasitic transition
may enhance the practical exploitation of this fungus. To reveal the genetic and metabolic
diversity of the fungus, we analysed differential gene expression under contrasting nutrient
conditions. An RNA fingerprinting technique was used to generate cDNA-amplified
fragment length polymorphisms (cDNA-AFLP) enabling identification of different gene
expression profiles. Conidia of two P. chlamydosporia isolates, VC10 and VC280,
preferentially parasitising Meloidogyne incognita (root-knot) and Globodera pallida (cyst
nematode), respectively, were inoculated in rich medium. Germinated conidia were harvested
after 5 days, washed and transferred to fresh rich and/or weak media. After 24 hours, cultures
were challenged with nematode eggs or a water control. Total RNA was extracted over a predefined
time course and used as template for cDNA-AFLP analysis. Using 12 primers
combinations, the 2-b primer selective extensions yielded around 50 labelled fragments per
track from the P. chlamydosporia-cyst nematode interaction, indicating both differentially
and constitutively expressed genes. Representative bands were excised from the gel, cloned
and sequenced. Most fragments ranged in size from 65 to 425 bp. The transcript derived
fragment sequences (TDFs) were analysed for similarities in the Genbank database. Of the 30
differentially expressed P. chlamydosporia TDFs analysed in this study, 6 corresponded to
sequences with known function, 15 matched to sequences coding for conserved hypothetical
or unknown function proteins and 9 presented no similarities in the databases searched. In all
instances the sequence similarities were of fungal origin. Based upon their similarities the
5 th International Congress of Nematology, 2008 293