« We received aphids infected with the different beet yellows viruses: BYV (severe jaundice), BMYV (moderate jaundice) and BChV (chlorosis) », Rejoices Jean-Noël Thauvin. ” They come directly from Strube, Germany “. The young engineer, hired by Deleplanque since February 2021, works in Estrées-Saint-Denis with two other technicians from the group. Installed in the premises of the breeder Asur Plant Breeding, it tests the resistance of varieties to jaundice viruses.
They bring viruliferous aphids… In the fields
« We start by multiplying infected aphids on beets, in confined spaces in greenhouses. », He reveals. And it is not an easy task, since from about thirty aphids infected by virus, it will have to obtain enough aphids to inoculate the 1500 micro-plots of tests. ” We have two months to multiply the aphids », Continues Jean-Noël Thauvin. Jaundice does not spread to offspring of aphids infected with severe jaundice virus. Aphids acquire it from infected plants, which is not the case with moderate jaundice viruses where infected aphids can transmit the virus to their offspring.
In a second step, the researchers infest the beets to be tested in the field by depositing aphids carrying the various viruses. The first inoculation took place in mid-May, with aphids infected with a combination of viruses, from moderate to severe.
The team is testing several hundred fairly diverse genotypes, either in the open field or in a tunnel (very exotic varieties, beta maritima, red beets, etc.) in Estrées-Saint-Denis. A yield test on 40 genotypes carried out in the Somme completes this system. The choice of the collection of genotypes made by the Strube team in Germany reflects as much as possible the diversity present within the genus Beta, and should make it possible to identify resistance genes.
« For elite genotypes, the yield is measured and the ability to resist or tolerate different viruses is observed. For other varieties, a PCR (polymerase chain reaction) quantitative determines the rate of contamination every week », Specifies the expert in genetics. Visual notations and monitoring of plots with a drone will also make it possible to monitor the impact of the disease on the different genotypes.
Partnership with Saaten-Union
This experiment is part of the Modefy program, a beet yellows control program initiated by the Deleplanque group. It brings together ITB, Inrae de Colmar and the Deleplanque group, for an approach that is not only genetic, but also agronomic and agroecological. The Asur Plant Breeding site in Estrées-Saint-Denis has established itself in the heart of a sugar beet region. In addition, Deleplanque has links with the Saaten-Union group which houses Asur Plant Breeding (it has a minority stake) and shares breeding programs, such as for rye, with a subsidiary of Saaten-Union. Finally, the researchers have at their disposal tunnels and greenhouses near the test fields.
As for the financing of the Modefy project, it is provided by the Deleplanque Group and by the Île-de-France and Grand Est regions.
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