GENERATION OF HYDROGEN PEROXIDE AND SUPEROXIDE RADICALS IN PEARS FOLLOWING ATTACK OF ERWINIA AMYLOVORA

Responses of host cells against the attack of Erwinia amylovora have not been studied well.
In this research, resistance levels of pear rootstocks, OH×F40, OH×F87, OH×F69, OH×F333 and two control pear cultivars, ‘Bartlett’ (susceptible) and ‘Harrow Sweet’ (resistant), were studied by pathogen inoculation and evaluation of necrosis progress rate on in vitro shootlets.
Also, generation of hydrogen peroxide (H₂O₂) and superoxide (O₂^–) radicals were traced in the course of disease progress.
Pear shootlets were inoculated with E. amylovora strain Ea273 and disease progress was followed for 144 h after inoculation.
H₂O₂ and O₂^– generation were traced using diaminobenzidine (DAB) and nitro blue tetrazolium (NBT), respectively.
Results indicate a classification of resistance from OH×F69 > OH×F87 > Harrow Sweet > OH×F333 > Bartlett > OH×F40. H₂O₂ generation demonstrated an inverse relation to necrosis appearance: more tolerant cultivars and rootstocks had faster H₂O₂ generation rates and slower necrosis development.
On the other hand, the pattern of O₂^– generation was not so well defined.
Apparently, H₂O₂ plays an inhibitory role against pathogen invasion, while O₂^– is destructive for host tissue.

XIII International Workshop on Fire Blight

S.R. Azarabadi, M. Torabi, H. Abdollahi, M. Hassani

Pyrus communis L., fire blight, resistance, H₂O₂, O₂^–, reactive oxygen species

https://doi.org/10.17660/ActaHortic.2014.1056.34