Potato soft rot is one of the major destructive diseases affecting potato plants throughout the world. In a survey of different potato growing seasons in different regions of Jordan, samples of rotten potato tubers were collected and 131 isolates identified biochemically as Pectobacterium carotovorum subsp. carotovorum (Pcc). The PCR primer pair (EXPCCR/EXPCCF) was used to detect these Jordanian isolates. The primer set amplified a single fragment of 550 bp in size from the total genomic DNA, which was extracted independently from 67 Pcc strains. In a nested PCR, the primer set (INPCCR/INPCCF) amplified the expected single fragment of 400 bp from the PCR product of first PCR amplification. The use of these primers was not reliable in detecting all isolates identified biochemically as Pcc. Different rots causal agents were detected by PCR amplification and further sequenced. The sequencing data revealed similarities to different genera; Pseudomonas, Enterobacteriaceae genera such as Enterobacter spp., Serratia spp. and Klebsiella spp., in addition to P. carotovorum subsp. carotovorum. So far this is the first study where Pcc has been identified by using PCR and sequencing approaches in Jordan.
Different studies were done in order to investigate the occurrence of bacterial diseases on different crops grown in Jordan during different growing seasons. Surveys were made and different bacterial diseases have been recorded based on symptoms and pathogenic nature. Morphological characters, biochemical tests and PCR detections were employed in order to detect and identify the causal agents of different inspected plant bacterial diseases. In addition, the distribution of the identified bacterial diseases, throughout the country was recorded. The results of our study revealed the occurrence of different bacterial diseases attacking different crops; grown in many growing regions throughout the country. Some of them were found to have a wide host range such as crown gall and soft rot, while others had a restricted host range as in the case of bacterial speck of tomato which was found to be restricted to tomato and black leg of potato. As a result of this study, the following diseases; angular leaf spot of cucumber, tomato speck, common blight, crown gall, soft rot, black rot, black leg and bacterial cankers resulted in high economic losses in yield. The spread of these diseases in the different areas in Jordan with different environmental conditions may result in the development of new races of the causal agents without developing typical symptoms making their diagnoses under field conditions difficult. Whereas the bacterial diseases needs deep and ideal studies in order to diagnose diseases, the diagnoses of these diseases act as the base for researchers to challenge and withdraw researches into the improvement of novel, more effective and sustainable bacterial disease control strategies.
Various bacterial species are known to be agents causing soft rot of potatoes. The results of this study showed that potato soft rot is widely spread in different potato planting areas in Jordan. A survey was conducted through the years 2013-2015 to detect potato soft rot disease in Jordan, two hundred and four rotted potato samples were collected from different potato growing areas through different potato growing seasons. One hundred and thirty one bacterial isolates were isolated, purified on selective media and identified as Pectobacterium carotovorum subspecies carotovorum (Pcc) by different biochemical and physiological tests. Furthermore, 131 Pcc Jordanian (Jo) isolates were identified by PCR analysis of total DNA extracted from isolates that were biochemically identified as Pcc using universal primer Fd1/Rd1. Cloning and sequencing of representative PCR products, amplifying the 16S rDNA region were done. Phylogenetic analysis of the Pcc Jo-isolates revealed other than 90% similarity with different reference Pcc strains available at the GenBank. Different rot causal agents also were detected by PCR amplification and further sequences. The sequencing data revealed similarities to Pseudomonas fluorescence, Enterobacteriaceae genera such as Enterobacter spp., Serratia spp. and Klebsiella spp., in addition to Pectobacterium carotovorum subsp. carotovorum. This study indicated that using molecular techniques such as amplification of 16S rDNA region is a sensitive and specific method for detecting Pcc as potato soft rot causal agent. So far this is the first study where Pcc has been identified by using PCR and sequencing approaches in Jordan.
Bacterial soft rot disease is one of the most important factors affecting potato production in Jordan. Based on biochemical and physiological analyses, Jordanian isolates of soft rot from potato were identified as Pectobacterium carotovorum subspecies carotovorum (DYE 1969). Phylogenetic analysis using pmrA gene sequence data showed that isolates from different regions were closely related to each other, whereas little genetic diversity was observed between these isolates. A DNA marker was developed from nucleotide sequences of the pmrA gene and a 318 bp fragment was polymerase chain reaction (PCR) amplified specifically from P. carotovorum subspecies carotovorum isolates, which could be used for detection of the disease in potato tubers.
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