Downward Vascular Translocation of a Green Fluorescent Protein-Tagged Strain of Dickeya sp. (Biovar 3) from Stem and Leaf Inoculation Sites on Potato

Abstract

Translocation of a green fluorescent protein (GFP)-tagged Dickeya sp. from stems or from leaves to underground parts of potato plants was studied in greenhouse experiments. Thirty days after stem inoculation, 90% of plants expressed symptoms at the stem base and 95% of plants showed browning of internal stem tissue. The GFP-tagged Dickeya sp. was detected by dilution plating in extracts of the stem interiors (100%), stem bases (90%), roots (80%), stolons (55%), and progeny tubers (24%). In roots, the GFP-tagged Dickeya sp. was found inside and between parenchyma cells whereas, in stems and stolons, the GFP-tagged Dickeya sp. was found in the xylem vessels and protoxylem cells. In progeny tubers, this strain was detected in the stolon end. Thirty days after leaf inoculation, the GFP-tagged Dickeya sp. was detected in extracts of 75% of the leaves, 88% of the petioles, 63% of the axils, and inside 25% of the stems taken 15 cm above the ground level. UV microscopy confirmed the presence of the GFP-tagged Dickeya sp. inside petioles and in the main leaf veins. No blackleg or aerial stem rot and no translocation of the GFP-tagged Dickeya sp. to underground plant parts was observed. The implications for contamination of progeny tubers are discussed.

Role of co‐infection by Pectobacterium and Verticillium dahliae in the development of early dying and aerial stem rot of Russet Burbank potato

“…Although internal movement of bacteria was detected in both acropetal and basipetal directions, more bacteria were detected in basal stem samples compared to apical stem samples using qPCR, indicating a trend towards basipetal movement of the bacteria in planta . This is consistent with a previous study that also observed an overall basipetal movement of Dickeya chrysanthemi in potato using a strain tagged with a green fluorescent protein (Czajkowski et al ., ). However, preliminary experiments using the same wound‐inoculation method as this study did not yield pectolytic bacteria from surface‐disinfested progeny tubers (data not shown), suggesting that isolates Ec101 and PwO405 did not readily translocate to progeny tubers in a systemic fashion.…”

Colonization Patterns of an mCherry-Tagged Pectobacterium carotovorum subsp. brasiliense Strain in Potato Plants

“…Furthermore, D. solani, a member of the SRE, has also been shown to utilize xylem vessels to systemically colonize potato plant tissues following root, stem, and leaf infection. The bacteria is reported to colonize within and between parenchyma cells in roots, xylem vessels, and protoxylem cells in stems and stolons, as well as the stolon ends of progeny tubers (11).…”

“…This was done using a 200-µl pipette tip, which was stabbed halfway into the stem at an angle of 45°. The inoculated part of the stem was then sealed with parafilm to prevent desiccation and leakage of inoculum down the stem or into the soil (11). Following inoculation, plants were watered every second day from the bottom of the pots (12,30).…”

Genomic and metabolic comparison with Dickeya dadantii 3937 reveals the emerging Dickeya solani potato pathogen to display distinctive metabolic activities and T5SS/T6SS-related toxin repertoire

“…Even if only a few genetic markers were analysed in several D. solani isolates from different countries, their high similarities suggested a clonal origin of D. solani populations affecting the potato plant host [4-6,8]. Remarkably, under greenhouse conditions at a high temperature (28°C), when the two bacterial species D. solani and D. dianthicola are coinoculated, D. solani isolates outcompete those of the other Dickeya species, revealing a high efficiency for colonizing potato roots and stems [9,10]. The genes and functions involved in these traits are still unknown.…”