Joint International Conference on Long-term Experiments ...

TISSUE CULTURE METHODS FOR SCREENING RESISTANCE TO
PECTOBACTERIUM CHRYSANTHEMI IN POTATO
Ildikó Hudák 1 , Mária Hevesi 2 , Judit Dobránszki 1 and Katalin Magyar-Tábori 1
1 Research Centre of University of Debrecen, Westsik V. u. 4-6, H-4400 Nyíregyháza,
2 Corvinus University of Budapest, Faculty of Horticultural Science, Villányi út 29-43.,
H-1118 Budapest, Hungary
ABSTRACT
Pectobacterium chrysanthemi (Erwinia chrysanthemi) cause vascular wilts, stunting,
soft rot, spotting of leaves or parenchymal necroses of a wide range of plant species and
cultivars like Allium cepa, Capsicum anuum, Nicotiana tabacum and Solanum
tuberosum. This bacterium affects potatoes in almost every region in the world. At the
moment the chemical protection is not solved (Dobránszki and Hevesi, 2002.). Altought
the sensitivity of produced cultivars are different, resistant cultivars are not available for
management of these diseases. The resistance in potato usually comes from wild
Solanum species. In our Research Centre we have bred potato for more decades. Our
breeding work based on using of the different wild Solanum species bearing resistance
or tolerance against Pectobacterium species (Hudák et al., 2002.). The aim of our
research is working out new in vitro methods for evaluation of the level of resistance or
tolerance against potato soft rot. We infected in vitro planlets. For evaluation of the
data, disease rating was used. By the help of disease rate we quantified the differences
among potato clones. On the basis of our results the in vitro methods may be suitable
for fast test of the breeding materials, clones or cultivars against Pectobacterium-strains.
Keywords: Pectobacterium chrysanthemi, soft rot, disease rate, in vitro methods
INTRODUCTION
Pectobacterium species causes plant diseases that include blights, cankers, die back,
leaf spots, wilts, discoloration of plant tissues and especially soft rots variously
described as stalk rot, crown rot, stem rot or fruit collapse (Brenner et al., 2005.).
Pectobacterium chrysanthemi (Erwinia chrysanthemi) is one of the phytopathogenic
enterobacteria, which causes soft rot disease in various plants. This bacterium affects
potatoes in almost every region in the temperate, semitropical and tropical zone of the
world. Its pathogenecity is due to its ability to secret several extracellular enzymes
including pectate lyases, cellulases and proteases. These extracellular enzymes attack
cell walls and membranes of plants leading to plant tissue maceration (Kelman, 1990.).
Because the field experiments would be dangerous and prolonged therefore an in vitro
method should be elaborated. We carried out with Pectobacterium-strain isolated in our
country. We adopted and compared different in vitro infection methods. We infected in
vitro planlets. We described the symptoms after in vitro infection.
MATERIALS AND METHODS
We used the bacterial strain isolated by Mária Hevesi in Hungary. In vitro cultured
shoots of potato Boró, Réka, Rachel, 136/92 and 34/85 were used as test plants. The
shoots were propagated on hormone-free MS medium. The cultures were illuminated by
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