A ProMED-mail post
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ProMED-mail is a program of the
International Society for Infectious Diseases
http://www.isid.org

Date: Mon 11 Dec 2023
Source: HortiDaily [summ. Mod.DHA, edited]
https://www.hortidaily.com/article/9583715/crazy-roots-outbreak-tackled-at-belgian-tomato- grower/


A Belgian tomato grower was confronted with an outbreak of 'Crazy Roots' [hairy root disease]. The infection reached its peak in 5 months, with 75% of the plants found to be infected. The disease is caused by _Rhizobium_ [previously _Agrobacterium_ - Mod.DHA] _rhizogenes_ which has a wide host range, for example tomato, aubergine and cucumber.

The bacterium is able to transfer part of its DNA into the plant cell, leading to the production of opines that can be used as a food source by the bacterium. Plant cells also become more sensitive to auxins [root inducing plant hormones - Mod.DHA], resulting in excessive root formation. This leads to more vegetative plant growth, thickened stems, problems with fruit production and a higher risk of secondary infections.

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Communicated by:
ProMED

[Strains of _Rhizobium rhizogenes_, as well as of related _Agobacterium_ and _Rhizobium_ species without the ability to induce excessive rooting or tumour formation are being used as genetic vectors in transformation systems for improvement of various crop species, including tomato (see links below). Since a potential source of the infection above has not been mentioned, it could be important to investigate whether there may be a connection with any strains used on the crop previously, either wild type source strains or reverted mutations.

Pictures
Hairy (or crazy) root symptoms (different hosts):
https://lbst.dk/fileadmin/user_upload/NaturErhverv/Billeder/Skadegorer/Bakterier/B001.jpg,
https://media.springernature.com/m312/springer-static/image/art:10.1007%2Fs11627-007-9096-8/MediaObjects/11627_2007_9096_Fig4_HTML.gif and
http://3.bp.blogspot.com/-7Hp0fgUZCGM/Uu8N9g_sWNI/AAAAAAAAaUI/gEALnS_9TP4/s1600/Tumor+formado+por+A.+rhizogenes+en+remolacha.jpg (culture)

Links
Information on _R. rhizogenes_:
https://gd.eppo.int/taxon/AGRBRH (with pictures),
https://image5.slideserve.com/9335186/agrobacterium-rhizogenes-inducer-of-roots-l.jpg,
https://www.slideserve.com/shelby/understanding-expression-of-agrobacterium-rhizogenes-proteins-galls-required-for-gene-transfer-to-plants,
https://www.plantcelltechnology.com/bloghairy-root-culture-definition-process-and-applications/ and
https://lbst.dk/tvaergaaende/plantesundhed/plantesundhed-for-professionelle/leksikon-over-planteskadegoerere/bakterier/agrobacterium-rhizogenes (in Danish)
Bacterial taxonomy via:
http://www.uniprot.org/taxonomy/
- Mod.DHA

ProMED map:
Belgium: https://promedmail.org/promed-post?place=8713688,99]

Website: http://www.isid.org

Published: December 13, 2023