#Bacterial blight of endive serial#

#Bacterial blight of endive serial#

The assay was first evaluated with greenhouse irrigation water spiked with serial dilutions of P. Sample preparation and DNA isolation were optimized to allow detection in 1 L water samples. Detection threshold with excellent reproducibility was 500 fg of DNA or about 70 genome copies. cichorii DNA concentrations was linear over 6‐logs. The relationship between detection signals and P. cichorii strains, including the type strain, and 89 strains from 83 other Pseudomonas species. Specificity of the assay was tested with 39 P. A sensitive real‐time PCR assay was developed, based on a 90‐bp amplicon from the pathogenicity gene cluster hrcRST and a Taqman Minor Groove Binding probe. Concentrations of 100 CFU mL−1 are enough to induce the typical midrib rot symptoms. It is for this reason that it is rife mainly during prolonged rainy periods, during which the water deposited on the leaves is favorable to contamination and its dissemination.Midrib rot is an emerging disease in greenhouse production of lettuce caused by Pseudomonas cichorii, and probably introduced through contaminated irrigation water. She particularly likes environments humid. Pseudomonas cichorii thrives at temperatures between 5 and 35 ° C, its optimum being around 20-25 ° C. Conditions favorable to its development Contaminated plants in nurseries also ensure its dissemination. It can be acquired and transmitted by the leafminer Liriomyza trifolii on chrysanthemum. This is particularly the case on some host plants attacked by this bacterium. It certainly takes place through splashing water, runoff and normally through seeds. The bacteria, behaving like a vascular microorganism, would be responsible for browning the main veins. In heavily infested soils, contamination via the roots or the taproot could occur. The browning of the tissue progresses from the epidermis to the mesophyll. The first spots appear quickly after contamination (about 30 hours). As the harvest approaches, the level of the bacterial population increases and the inoculum pressure intensifies. The outer leaves constitute an important source of inoculum allowing the contamination of the leaves of the heart subsequently. Population density fluctuates during the salad cycle depending on climatic conditions and perhaps salad types. In fact, this bacterium is present on the surface of the leaves throughout the growing cycle of salads. Direct contaminations through the cuticle are rare and occur when the leaves are covered and saturated with water. Many bacteria can be noted in the guard cells and in the intercellular spaces of the epidermis. It mainly penetrates the salad leaves through natural openings, such as the stomata, or wounds (growth bursts, wounds due to the wind, insect damage or related to cultivation operations, etc.). Pseudomonas cichorii does not seem to have considerable parasitic potential on lettuce. Certain tools and harvest boxes are also sources of contamination.Ĭontamination can take place at the end of the rosette stage, thanks to rains or irrigation.

It can be stored on seeds for several months and would survive in certain contaminated water reserves. ) and many weeds: Sonchus oleracea, Veronica sp., Solanum nigrum, Portulaca oleracea, Poa annua, Setaria sp., Senecio vulgaris, Capsella bursa-pasteuris. It is found in the pathogenic state on several vegetables, such as cabbage, endive, celery, tomato, eggplant, several legumes, tobacco, flowers (gerbera, chrysanthemum, pelargonium. It colonizes the rhizosphere of a good number of hosts, cultivated or not. This bacterium (Figure 1) was isolated directly from soil in Japan. Pseudomonas cichorii is very easily maintained in soil and on plant debris.