Causative Pathogen of Fire Blight of Fruit Trees in Georgia: The paper is funded by the Shota Rustaveli National Science Foundation of Georgia (GSRF), grant number FR-19-22524.

The paper is funded by the Shota Rustaveli National Science Foundation of Georgia (GSRF), grant number FR-19-22524.

Abstract

Fire blight is a devastating disease of fruit trees that first appeared in Georgia in 2016. Above 40 samples – fruit trees twigs, buds, flowers and fruitlets, suspected on the fire blight disease were collected in the Mtskheta-Mtianeti and Shida Kartli Regions, eastern Georgia in Summer of 2020. Based on visual observation and immunological test (Ea AgriStrip), 20 plant samples were selected for further study. PCR analysis was performed to detect pathogen in these samples with primers pair A: 5′-CGG TTT TTA ACG CTG GG-3′ and B: 5′-GGG CAA ATA CTC GGA TT-3 ′ and 2XPCR BIOTAG Mix using PCR BIOSYSTEMS. The pathogen Erwinia amylovora was detected in 6 samples: N10 and N11 apple samples (Ksovrisi); N12 apple sample (Kekhijvari); N14 apple sample (Karaleti); N16- apple sample (Tirdznisi); N27 pear sample (Osiauri). King’s B, NSA and CCT media were used for the isolation of the pathogen from PCR-confirmed diseased samples serial dilutions. For the identification of Erwinia amylovora,  PCR was performed in 25 μl reaction mixture with primers pair G1-F: 5′-CCT GCA TAA ATC ACC GCT GACAGC TCA ATG 3’ and G2-R: 5GCT ACC ACT GAT CGC TCG AATCAA ATC GGC3′. The presence of E. amylovora was confirmed in the following isolates, ## 1012, 1022, 1023, 1131, 1133, 1212, 1412, 1612, 1742, and 2763.  Study of the physiological-biochemical properties of the E. amylovora Georgian isolates revealed a little difference in the sugars utilization and the esculin hydrolysis abilities.