TABLE CONTENTS

TOPIC THIRTEEN – INTERACTIONS OF NEMATODES WITH
MICROORGANISMS
Diversity of Endophytic Bacteria Isolated from Pine Trees with Pine Wilt
Disease
Vieira dos Santos, M.C. (1); D. Proença (2), L. Fonseca (1), I.M. de O. Abrantes (1) & P. V.
Morais(2)
(1) IMAR-CIC and Departamento de Zoologia, Faculdade de Ciências e Tecnologia, Universidade de Coimbra,
3004-517 Coimbra, Portugal; (2) IMAR-CIC and Departamento de Bioquímica, Faculdade de Ciências e
Tecnologia, Universidade de Coimbra, Apartado 3126, 3001-401 Coimbra, Portugal.
The characteristic rapid death of maritime pine, Pinus pinaster, after infection by the
pinewood nematode (PWN), Bursaphelenchus xylophilus, suggests the involvement of other
organisms in pine wilt disease (PWD). Microorganisms are common companions of plant
roots, but few reports describe their presence in the aerial parts of plants. Endophytic bacteria
are ubiquitous in nature and colonize a broad spectrum of plant species. They colonize plants
internally without harming them and have been reported to promote their growth and
stimulate plant defence mechanisms. They may be involved in improving plant health but
they have also been seen as one potential cause of the low regeneration capacity of mature
trees. The bacteria carried out by the PWN through pine trees may also contribute to the rapid
wilting of the maritime pine trees. Fifty-one bacteria strains were isolated from infected pine
wood and PWN trails, these were RAPD typed and identified by sequence of the 16S rDNA
gene. The endophytic microbial community isolated included 17 RAPD types.
Betaproteobacteria were isolated from pine trees but the majority of the strains identified
belonged to the Gammaproteobacteria group. Six different bacteria strains were isolated
from the nematode trails. Although they belonged to the Gammaproteobacteria group, they
were distinct from the endophytic bacteria. These nematode-related bacteria were
phylogenetically closely related to bacteria strains previously isolated from wood-boring
organisms.
5 th International Congress of Nematology, 2008 253