Hasan Murat Aksoy

Fasulye üretim alanlarında hastalığa neden olan Xanthomonas axonopodis pv. phaseoli ve Pseudomonas savastonoi pv. phaseolicola’nın izolasyonu ve tanılanması

2013-2014 yillarinda, Samsun ili fasulye uretim alanlarinda adi yanikliga neden olan Xanthomonas axonopodis pv. phaseoli ( Xap ) ve hale yanikligina neden olan Pseudomonas savastonoi pv. phaseolicola ( Psp )’nin belirlenmesi icin surveyler yapilmistir. Elde edilen tek ve saf kolonilerle yapilan biyokimyasal, patojenisite, molekuler ve 16S rDNA sekanslama calismalari sonucunda 8 Xap ve 5 Psp izolati tanilanmistir. Xap ve Psp izolatlari filogenetik agac analizinde tip kulturleri ile birlikte yer almistir. Goynuk 98 fasulye cesidi in vitro patojenisite denemelerinde en hassas cesit olarak belirlenmistir ve virulens denemesi icin kullanilmistir. Yapilan bu calismada, Turkiye taze fasulye uretiminin % 20’sinin gerceklestigi Samsun ilinde her iki hastalik etmenin varligi molekuler calismalarla ilk kez ortaya konmustur.

Expression of the dspA/E gene of Erwinia amylovora in non-host plant Arabidopsis thaliana

ABSTRACT In the Erwinia amylovora genome, the hrp gene cluster containing the dspA/E/EB/F operon plays a crucial role in mediating the pathogenicity and the hypersensitive response (HR) in the host plant. The role of the dspA/E gene derived from E. amylovora was investigated by monitoring the expression of the β-glucuronidase (GUS) reporter system in transgenic Arabidopsis thaliana cv. Pri-Gus seedlings. A mutant ΔdspA/E strain of E. amylovora was generated to contain a deletion of the dspA/E gene for the purpose of this study. Two-week-old seedlings of GUS transgenic Arabidopsis were vacuum-infiltrated with the wild-type and the mutant (ΔdspA/E) E. amylovora strains. The Arabidopsis seedlings were fixed and stained for GUS activity after 3–5 days following infiltration. The appearance of dense spots with blue staining on the Arabidopsis leaves indicated the typical characteristic of GUS activity. This observation indicated that the wild-type E. amylovora strain had induced a successful and efficient infection on the A. thaliana Pri-Gus leaves. In contrast, there was no visible GUS expression on leaf tissues which were inoculated with the ΔdspA/E mutant E. amylovora strain. These results indicate that the dspA/E gene is required by the bacterial cells to induce HR in non-host plants.

FIRST REPORT OF PECTOBACTERIUM CAROTOVORUM SUBSP. BRASILIENSE CAUSING BLACKLEG AND SOFT ROT OF POTATO IN TURKEY

In the summer of 2015, potato plants exhibiting blackleg symptoms were surveyed in 10 commercial fields in Amasya province in the Black Sea Region of Turkey. Average disease incidence was approximately 11% in the surveyed area, but could reach up to 40%. Stem tissue of diseased plants was homogenised and extract was plated on Nutrient Agar (Himedia, India). After 24 h incubation at 28°C single colonies were purified on Luria Agar (Himedia, India) or Crystal Violet Pectate (CVP) medium (Hyman et al., 2001). A total of nine strains that were cavity forming on CVP, gram-negative, catalase positive and facultative anaerobic with pectinolytic ability, produced a 434 bp product with pel gene specific primers Y1/Y2 (Darrasse et al., 1994) designed for Pectobacterium spp. One of these strains (A4G1) produced a 322 bp fragment typical for Pectobacterium carotovorum subsp. brasiliense using the subspecies specific primers (Br1f/Lr1) in the PCR assay (Duarte et al., 2004). Blastn analysis with a 1402 bp partial 16S rDNA gene sequence of strain A4G1 (GenBank Accession No. KX548227) showed 99% similarity to the 16S rDNA of P. carotovorum subsp. brasiliense strain 1001 (JF926759) at the nucleotide level. Phylogenetic tree analysis based on the Maximum Likelihood method, using 16S rDNA sequences avaliable in GenBank, clustered the two strains together. Surface sterilized whole potato tubers (cv. Marabel) were stabbed with a sterile pipette tip and inoculated with a 20 μl suspension of 108 cfu ml-1 of an overnight culture grown at 28 C. Inoculation wounds were covered with mineral oil to maintain partly anaerobic conditions in a dew chamber at 26°C. Strain A4G1 caused soft rot of tubers after 48 h incubation. Reisolated colonies caused pitting on CVP and exhibited the same morphology as original cultures on the NA plates. To our knowledge, this is the first report on the presence of P. carotovorum subsp. brasiliense in Turkey.