About chemical composition of the nematode Ditylenchus Dipsaci

In the article are presented data on the quantitative variations of bound amino acids in the tissue protein of the nematode Ditylenchus dipsaci Kuhn, 1857, parasite of Allium sativum crops. It was revealed that the largest share is: glutamic acid + glutamine -21.0% of the total amount, aspartic acid + asparagine - 11.0%, glycine -12.6% and alanine -10.5. In smaller quantities was evidenced: tryptophan (0.8%), histidine (0.8%) and methionine (0.1%). According to the distribution by groups, it was determined that non-essential amino acids have the highest percentage of the total -31.9%, followed by immunoactive amino acids - 25.7% and glycogen - 21.5%.

Screening of sugar beet pre-breeding populations and breeding lines for resistance to Ditylenchus dipsaci penetration and reproduction

Ditylenchus dipsaci is an economically important plant-parasitic nematode affecting European sugar beets. To date, no sugar beet cultivars carrying resistance against D. dipsaci are available to farmers. To find potentially resistant sugar beet lines restricting reproduction and penetration of D. dipsaci, three consecutive in vivo bioassays were carried out. The first experiment determined the penetration rate of D. dipsaci in 79 breeding lines and 14 pre-breeding populations. Based on these results, D. dipsaci penetration and reproduction resistance of eight genotypes was intensively investigated. It could be demonstrated that none of the genotypes showed resistance towards D. dipsaci. However, a high variation of the penetration rate by D. dipsaci was observed among the genotypes. The breeding line ‘DIT_119’ effectively reduced D. dipsaci penetration (34.4 ± 8.8 nematodes/plant at 22 days post-planting) compared to the susceptible control (109.0 ± 16.9) while ensuring a yield comparable to non-inoculated plants. However, the breeding line ‘DIT_119’ did not reduce D. dipsaci reproduction. The paternal line of the cultivar BERETTA KWS, demonstrating a high tolerance to D. dipsaci crown rot symptoms, did not reduce penetration and reproduction. Thus, no correlation can be established between reduced penetration rates, reproduction, and tolerance to D. dipsaci. This study provides an essential basis for the development of resistant sugar beet cultivars to D. dipsaci. The variations observed among genotypes now need to be confirmed with larger-scale screenings.

Virulence and pathogenicity of four Ditylenchus dipsaci populations on sugar beet

The stem nematode, Ditylenchus dipsaci, is a severe pest in European sugar beet production. In France, Germany, and Switzerland, D. dipsaci damage in sugar beet varies among specific geographic areas. In this study, the reproduction potential of four geographically distinct D. dipsaci populations was determined using sterile carrot disc cultures. In addition, virulence and pathogenicity were investigated in-vivo using sugar beet. No difference was found in the reproduction potential on carrot discs, as well as penetration rate in sugar beet seedlings. The reproduction rate in sugar beet tissue was significantly affected by the D. dipsaci population used. The population from Seeland (CH) showed the highest number of nematodes per plant at 60 dpi (21,071.8 ± 5340.0), compared to the three other populations contained 3588.6 ± 3858.3, 5136.9 ± 4950.8, and 3579.7 ± 5174.2, respectively. Furthermore, the reproduction rate of D. dipsaci was negatively correlated with fresh biomass of sugar beets at 60 dpi. Based on these results, the D. dipsaci population “Seeland” is suitable for breeding programs to detect resistance in sugar beet. After selecting candidate genotypes/varieties, these should be further evaluated for their field resistance in their targeted growing regions.