Page 45 - חוברת תזות הנדסה ירוקה 2023

Acidovorax pathogens: Identification and characterization of genes associated with the pathogenic pathway in cucurbits
Maram Osman1; othmanmaram1@gmail.com
Dr. Yoram Shotland1, Prof. Saul Burdman2
1Sami Shamoon College of Engineering, Beer-Sheva, Israel.
2 Department of Plant Pathology and Microbiology, Robert H. Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem.
The Acidovorax genus is a gram-negative, facultative bacteria belonging to the Betaproteobacteria class. It comprises various species with diverse lifestyles and is well- adapted to different environments. Some species developed an intimate relationship with eukaryotes, including plants. Among the latter, Acidovorax citrulli, a seedborne bacterium, attacks cucurbits at all stages of growth and causes bacterial fruit blotch )BFB( disease. BFB represents a considerable threat to the global cucurbits industry, especially melons and watermelons. Based on genetic and biochemical proprieties, strains of A. citrulli can be divided into two distinct groups, I and II. Group I strains mainly attack melons and non-watermelon cucurbits and are moderately to highly aggressive with many cucurbit hosts. However, Group II strains mainly attack watermelons and are highly aggressive with watermelons and weakly to moderately aggressive with other cucurbit hosts.
This research is a continuation of a junior thesis in which EDGAR software was used to evaluate the core genome of the Acidovorax genus and to identify putative pathogenicity genes of the Acidovorax spp. This work resulted in four databases containing 670 genes, supposedly exclusive to the genus’s pathogenic strains. However, validating EDGAR’s results using the Blast algorithm eliminated about 180 genes from the list. Next, we used a homology-based approach to rank the remaining genes according to their propensity for becoming central genes in the pathogenic pathway of Acidovorax spp. pathogens. Our hypothesis is that prevalent genes among Acidovorax and evolutionary-distant pathogens are most likely to play an essential role in the pathogenic pathway of the Acidovorax pathogens. Therefore, homologous genes were sought in numerous pathogens, including Acidovorax spp. and evolutionary-distant pathogens. Highly ranked genes were found to contribute to the virulence of different previously studied pathogens and their adaptation to changing environmental conditions encountered during infection. Among those are insertional sequences )ISs(, the major facilitator superfamily )MFS( transporters, anti-sigma regulatory factors, ankyrin repeat domain-containing proteins, 2,5-didehydrogluconate reductase, dkgB, and a ubiquitin family protein. Ubiquitin regulates various processes in eukaryotes and is known to attach proteins targeted for proteasomal degradation. This gene was one of the two chosen for in-vivo analysis. Moreover, signal peptide prediction
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