RESEARCH

Identification of the Causal Agent of Bacterial Leaf Spot on Watermelon in China

    Affiliations
    Authors and Affiliations
    • Pei Qiao1
    • Mei Zhao2
    • Dehua Liu3
    • Wei Guan1
    • Qingrong Bai3
    • Yuwen Yang1
    • Tingchang Zhao1
    1. 1State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
    2. 2Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing, China
    3. 3College of Plant Protection, Jilin Agricultural University, Changchun, China

    Published Online:https://doi.org/10.1094/PDIS-08-22-1878-RE

    Watermelon diseases caused by pathogenic bacteria were endemic in Liaoning and Jilin Provinces from 2019 to 2020 in China, resulting in serious economic losses to the watermelon industry. This study characterized 56 strains isolated from symptomatic watermelon leaves collected from Liaoning and Jilin Provinces. Through morphological observation, 16S rRNA and gyrB sequence analysis, and BIOLOG profiles, the pathogen was identified as Pseudomonas syringae. In China, the watermelon disease caused by P. syringae was reported for the first time. The multilocus sequence analysis showed that the isolated strains belonged to three different clades within P. syringae phylogroup 2. Interestingly, most of them (79%) belonged to clade 2a, 14% were clade 2b, and 7% were clade 2d. This indicates that bacterial leaf spot outbreaks of watermelon in China were caused by multiple sources and mainly by P. syringae clade 2a.

    Literature Cited

    • Aksoy, H. M. 2006. Occurrence of Pseudomonas syringae pv. lachrymans [(Smith and Bryan) Young, Dye and Wilkie] at Bafra Province greenhouses. Plant Pathol. J. 5:80‐82. https://doi.org/10.3923/ppj.2006.80.82 CrossrefGoogle Scholar
    • Bai, Q. R., Gu, Y., Chen, Y., Sun, Y. M., Wu, J. H., and Zhao, T. C. 2019. Pathogen identification and screening of the effective bactericides of muskmelon (Cucumis melo) bacterial leaf blight. Agrochemicals 58:209‐213 (in Chinese). Google Scholar
    • Bull, C. T., and Koike, S. T. 2015. Practical benefits of knowing the enemy: Modern molecular tools for diagnosing the etiology of bacterial diseases and understanding the taxonomy and diversity of plant pathogenic bacteria. Annu. Rev. Phytopathol. 53:157‐180. https://doi.org/10.1146/annurev-phyto-080614-120122 Crossref, ISIGoogle Scholar
    • Chen, H. T. 2019. Development Status, Problems and Advise of Chinese Watermelon and Melon Cultivation Pattern in China. Shenyang Agricultural University, Shenyang, China (in Chinese). Google Scholar
    • Dutta, B., Gitaitis, R. D., Driver, J. E., and Smith, M. S. 2016. First report of bacterial leaf spot on watermelon caused by Pseudomonas syringae pv. syringae in Georgia. Plant Dis. 100:518. https://doi.org/10.1094/PDIS-06-15-0658-PDN Link, ISIGoogle Scholar
    • Fang, Z. D. 1998. Plant Disease Research Method. China Agriculture Press, Beijing, China (in Chinese). Google Scholar
    • Gregersen, T. 1978. Rapid method for distinction of gram-negative from gram-positive bacteria. Eur. J. Appl. Microbiol. Biotechnol. 5:123‐127. https://doi.org/10.1007/BF00498806 CrossrefGoogle Scholar
    • Hua, J. Q., and Cai, J. 2005. Nutritional and medicinal value of watermelon. Food and Drug 7:67‐69 (in Chinese). Google Scholar
    • Hwang, M. S. H., Morgan, R. L., Sarkar, S. F., Wang, P. W., and Guttman, D. S. 2005. Phylogenetic characterization of virulence and resistance phenotypes of Pseudomonas syringae. Appl. Environ. Microbiol. 71:5182‐5191. https://doi.org/10.1128/AEM.71.9.5182-5191.2005 Crossref, ISIGoogle Scholar
    • King, E. O., Ward, M. K., and Raney, D. E. 1954. Two simple media for the demonstration of pyocyanin and fluorescin. J. Lab. Clin. Med. 44:301‐307. ISIGoogle Scholar
    • Kumar, S., Stecher, G., and Tamura, K. 2016. MEGA7: Molecular evolutionary genetics analysis version 7.0 for bigger datasets. Mol. Biol. Evol. 33:1870‐1874. https://doi.org/10.1093/molbev/msw054 Crossref, ISIGoogle Scholar
    • Lane, D. J. 1991. 16S/23S rRNA sequencing. Page 115‐175 in: Nucleic Acid Techniques in Bacterial Systematics. E. Stackebrandt, and M. Goodfellow, eds. John Wiley and Sons, New York, NY. Google Scholar
    • Lelliott, R. A., Billing, E., and Hayward, A. C. 1966. A determinative scheme for the fluorescent plant pathogenic pseudomonads. J. Appl. Bacteriol. 29:470‐489. CrossrefGoogle Scholar
    • Li, X. S., and Wang, S. M. 2014. Introduction and spread of pumpkin and its influence in China. Journal of Chinese Historical Geography 29:81‐92 (in Chinese). Google Scholar
    • Li, Y. L., Jia, Y. C., Pu, C. J., Xue, L., and Chen, X. R. 2006. Host plants of bacterial spot of cucurbits leaves infected by Pseudomonas syringae. J. Gansu Agric. Univ. 41:63‐66 (in Chinese). Google Scholar
    • Mitrev, S., and Arsov, E. 2020. First report of bacterial fruit blotch on watermelon caused by Acidovorax citrulli in the republic of North Macedonia. Plant Dis. 104:2721. https://doi.org/10.1094/PDIS-01-20-0204-PDN Link, ISIGoogle Scholar
    • Monteil, C. L., Yahara, K., Studholme, D. J., Mageiros, L., Méric, G., Swingle, B., Morris, C. E., Vinatzer, B. A., and Sheppard, S. K. 2016. Population-genomic insights into emergence, crop adaptation and dissemination of Pseudomonas syringae pathogens. Microb. Genom. 2:e000089. https://doi.org/10.1099/mgen.0.000089 Crossref, ISIGoogle Scholar
    • Mullin, I., and Schenck, N. C. 1963. Bacterial leaf spot on watermelon. Plant Dis. 47:848. Google Scholar
    • Newberry, E. A., Jardini, T. M., Rubio, I., Roberts, P. D., Babu, B., Koike, S. T., Bouzar, H., Goss, E. M., Jones, J. B., Bull, C. T., and Paret, M. L. 2016. Angular leaf spot of cucurbits is associated with genetically diverse Pseudomonas syringae strains. Plant Dis. 100:1397‐1404. https://doi.org/10.1094/PDIS-11-15-1332-RE Link, ISIGoogle Scholar
    • Newberry, E. A., Babu, B., Roberts, P. D., Dufault, N. S., Goss, E. M., Jones, J. B., and Paret, M. L. 2018. Molecular epidemiology of Pseudomonas syringae pv. syringae causing bacterial leaf spot of watermelon and squash in Florida. Plant Dis. 102:511‐518. https://doi.org/10.1094/PDIS-07-17-1002-RE Link, ISIGoogle Scholar
    • Newberry, E. A., Ebrahim, M., Timilsina, S., Zlatković, N., Obradović, A., Bull, C. T., Goss, E. M., Huguet-Tapia, J. C., Paret, M. L., Jones, J. B., and Potnis, N. 2019. Inference of convergent gene acquisition among Pseudomonas syringae strains isolated from watermelon, cantaloupe, and squash. Front. Microbiol. 10:270. https://doi.org/10.3389/fmicb.2019.00270 Crossref, ISIGoogle Scholar
    • Schaad, N. W., Sowell, G., Goth, R. W., Colwell, R. R., and Webb, R. E. 1978. Pseudomonas pseudoalcaligenes subsp. citrulli subsp. nov. Int. J. Syst. Bacteriol. 28:117‐125. https://doi.org/10.1099/00207713-28-1-117 CrossrefGoogle Scholar
    • Słomnicka, R., Olczak-Woltman, H., Bartoszewski, G., and Niemirowicz-Szczytt, K. 2015. Genetic and pathogenic diversity of Pseudomonas syringae strains isolated from cucurbits. Eur. J. Plant Pathol. 141:1‐14. https://doi.org/10.1007/s10658-014-0524-4 Crossref, ISIGoogle Scholar
    • Sun, F. Z., and He, L. Y. 1988. Identification of pathogen and host range of cucumber angular leaf spot. Acta Phytopathol. Sin. 18:23‐28 (in Chinese). Google Scholar
    • Tamura, K., and Nei, M. 1993. Estimation of the number of nucleotide substitutions in the control region of mitochondrial DNA in humans and chimpanzees. Mol. Biol. Evol. 10:512‐526. https://doi.org/10.1093/oxfordjournals.molbev.a040023 ISIGoogle Scholar
    • Tian, Y. L., Zhao, Y. Q., Chen, X. Z., Dai, Y. F., Zhao, W. J., Hu, B. S., and Walcott, R. R. 2017. Evidence for a novel phylotype of Pseudomonas syringae causing bacterial leaf blight of cantaloupe in China. Plant Dis. 101:1746‐1752. https://doi.org/10.1094/PDIS-01-17-0110-RE Link, ISIGoogle Scholar
    • Webb, R. E., and Goth, R. W. 1965. A seedborne bacterium isolated from watermelon. Plant Dis. Rep. 49:818‐821. Google Scholar
    • Wen, C. C., Sun, Y. Z., and Wu, J. X. 2016. China’s watermelon and muskmelon industry during the 13th five-year plan period. Agric. Outlook 12:48‐52 (in Chinese). Google Scholar