Tomate (Solanum lycopersicum) production and bacterial canker management during COVID-19

<p>The tomato (<em>Solanum lycopersicum</em>) is part of the food basket of Mexicans and is the most consumed vegetable worldwide. Mexico is one of the main producer and exporter countries, the main market to export is the United States of America. The pandemic caused by the severe acute respiratory syndrome coronavirus (SARS-CoV-2) seriously affected the economy and consequently the production and distribution of basic foods, including tomatoes. This work summarizes the experiences derived from the production, detection and phytosanitary management of <em>Clavibacter</em> <em>michiganensis</em> subsp. <em>michiganensis</em> during the July–December 2020 season in a tomato crop under macro tunnel located in Copándaro, Michoacán, Mexico. Agriculture, as an essential economic activity in the production of basic foods, must remain active as it is an unconfined productive process, with a low risk of contagion, and it’s a necessary activity for the economic support of agricultural workers.</p>

Isolation of the Novel Phage PHB09 and Its Potential Use against the Plant Pathogen Pseudomonas syringae pv. actinidiae

Bacteriophages are viruses that specifically infect target bacteria. Recently, bacteriophages have been considered potential biological control agents for bacterial pathogens due to their host specificity. Pseudomonas syringae pv. actinidiae (Psa) is a reemerging pathogen that causes bacterial canker of kiwifruit (Actinidia sp.). The economic impact of this pest and the development of resistance to antibiotics and copper sprays in Psa and other pathovars have led to investigation of alternative management strategies. Phage therapy may be a useful alternative to conventional treatments for controlling Psa infections. Although the efficacy of bacteriophage φ6 was evaluated for the control of Psa, the characteristics of other DNA bacteriophages infecting Psa remain unclear. In this study, the PHB09 lytic bacteriophage specific to Psa was isolated from kiwifruit orchard soil. Extensive host range testing using Psa isolated from kiwifruit orchards and other Pseudomonas strains showed PHB09 has a narrow host range. It remained stable over a wide range of temperatures (4–50 °C) and pH values (pH 3–11) and maintained stability for 50 min under ultraviolet irradiation. Complete genome sequence analysis indicated PHB09 might belong to a new myovirus genus in Caudoviricetes. Its genome contains a total of 94,844 bp and 186 predicted genes associated with phage structure, packaging, host lysis, DNA manipulation, transcription, and additional functions. The isolation and identification of PHB09 enrich the research on Pseudomonas phages and provide a promising biocontrol agent against kiwifruit bacterial canker.

Бактериофаги Pseudomonas syringae pv. syringae перспективные в подавлении развития бактериального рака плодовых

Five Pseudomonas syringae pv. syringae bacteriophages were isolated from the quince, apple and pear. After a detailed study, the isolated bacteriophages could be used for biocontrol of the bacterial canker patho-gen. One of the isolated phages was active against the causative agents of bacterial canker and fire blight.

Identification of strA-strB Genes in Streptomycin-Resistant Pseudomonas syringae pv. actinidiae Biovar 2 Strains Isolated in Korea

Bacterial canker is a devastating disease of kiwifruit caused by the bacterium <i>Pseudomonas syringe</i> pv. <i>actinidiae</i>. Canker disease of kiwifruit in Korea has been controlled using streptomycin for more than two decades. Four streptomycin-resistant strains, belonging to biovar 2, which are found only in Korea, were collected between 2013 and 2014 from different orchards located in Jeju, Korea. The genetic background for streptomycin resistance among <i>P. syringe</i> pv. <i>actinidiae</i> strains were determined by examining the presence of <i>strA</i>-<i>strB</i> or <i>aadA</i>, which are genes frequently found in streptomycin-resistant bacteria, and a point mutation at codon 43 in the <i>rpsL</i> gene. All four streptomycin-resistant strains of <i>P. syringe</i> pv. <i>actinidiae</i> investigated in this study contained <i>strA</i>-<i>strB</i> as a resistant determinant. The presence of the <i>aadA</i> gene and a mutation in codon 43 of the <i>rpsL</i> gene was not identified.

Antibacterial activity of Calendula officinalis and Echinacea purpurea extracts against the causal agent of tomatoes’ bacterial canker: Clavibacter michiganensis subsp. michiganensis

We aimed to investigate the effects of Calendula officinalis and Echinacea purpurea extracts in terms of growth parameters, antibacterial activity and phenolic profile in tomato infected by Clavibacter michiganensis subsp. michiganensis (CmmT7). A significant difference was observed in E. purpura extract, indicating the highest effects on plant height (27.25 cm), fresh plant weight (28.45 cm), root length (24.42 cm), and root weight (6.74 g) (p<0.05). Moreover, Calendula officinalis and Echinacea purpurea extracts showed significant inhibitory activity against CmmT7 (p<0.05). Among phenolic compounds, the only chlorogenic acid amounts were varied in the tomato seedlings leaves with C. officinalis extract (K3) + CmmT7, E. purpurea extract (E3) + CmmT7 and CmmT7 (p<0.01). Moreover, chlorogenic acid amount was approximately 9 times higher than in CmmT7-treated leaves when compared to control. The results showed that application of the extracts of these plants had a significant influence on bacterial canker and growth parameters.