A muscadine locus confers resistance to predominant species of grapevine root-knot nematodes (Meloidogyne spp.) including virulent populations

Root-knot nematodes (RKNs) Meloidogyne spp. are extremely polyphagous pests and four species severely affect grapevines throughout the world: M. arenaria, M. incognita, M. javanica and M. ethiopica. Californian populations of M. arenaria and M. incognita are reported to be virulent to widely used rootstocks and to the rootstock ‘Harmony’ in particular. Breeding RKNs-resistant grape rootstocks is a promising alternative to highly toxic nematicides. Muscadine (Vitis rotundifolia syn. Muscadinia rotundifolia) is a resistance (R) source with undercharacterised genetics. To this end, we used a segregating progeny between the RKN-resistant Vitis x Muscadinia accession ‘VRH8771’ from the muscadine source ‘NC184-4’ and the RKN-susceptible V. vinifera cv. Cabernet-Sauvignon. We first phenotyped its resistance to isolates of the i) M. arenaria, ii) M. incognita and iii) M. javanica species, and then to iv) two mixed Harmony-virulent Californian populations of M. arenaria and M. incognita. Finally, we created an isolate of M. arenaria and M. incognita from these Harmony populations and phenotyped the progeny to each of them [v) and vi)], and to vii) an isolate of M. ethiopica. The resistance phenotype of all the progeny’s individuals was independent of the RKN isolates or populations used. Resistance was mapped in a region of chromosome 18 in VRH8771, supporting the hypothesis that it is conferred by a single gene with an unprecedented wide spectrum in grapevine, including Harmony-virulent isolates. This dominant gene, referred to as MsppR1, is linked to the telomeric QTL XiR4 for X. index resistance from the same source. Additionally, plant mortality data showed that MsppR1-resistant material expressed a high-level resistance to the Harmony-virulent isolates. Our results are a first step towards the development of marker-assisted breeding using SSR and SNP markers for resistance to RKNs in accession VRH8771. © 2023, International Viticulture and Enology Society. All rights reserved

Unusual Transmission of Plasmodium falciparum, Bordeaux, France, 2009

Plasmodium falciparum malaria is usually transmitted by mosquitoes. We report 2 cases in France transmitted by other modes: occupational blood exposure and blood transfusion. Even where malaria is not endemic, it should be considered as a cause of unexplained acute fever

Xiphinema index-resistant grapevine materials derived from muscadine are also resistant to a population of X. diversicaudatum

Grapevine is severely affected by two major nepoviruses that cause grapevine degeneration: the grapevine fanleaf virus (GFLV) and the arabis mosaic virus (ArMV), specifically transmitted by the dagger nematodes Xiphinema index and X. diversicaudatum, respectively. While natural resistance to X. index has been shown to be a promising alternative for controlling X. index and GFLV transmission, the resistance interaction between X. diversicaudatum and grapevine has not yet been documented. In the present study, we evaluated the host suitability to X. diversicaudatum in materials previously characterised for their resistance to X. index. Two X. index-resistant accessions VRH8771 (F1 hybrid) and Nemadex Alain Bouquet (BC1 hybrid) derived from muscadine, together with the X. index-susceptible reference accession V. vinifera cv. Cabernet-Sauvignon and the X. index-resistant reference accession V. riparia ‘10128’, were challenged with a X. diversicaudatum population obtained from woody host plants and a reference isolate of X. index. The reproduction factors of X. diversicaudatum and its numbers per gram of roots paralleled those of X. index, showing a resistance interaction to the population of the former species and suggesting that resistance determinants to both nematode vectors might be the same or linked. Nevertheless, these two criteria illustrated a poorer host suitability of grapevine materials to this X. diversicaudatum population than to X. index

BMC Plant Biol

Combining innovation in vineyard management andgenetic diversity for a sustainable European viticultur

Long term effects of nitrogen and water supply on confered vigour and yield by SO4 and Riparia gloire de Montpellier rootstocks

Aims: the present study was designed to test the hypothesis according to which rootstock effects on scion growth and yield are related to fundamental physiological traits which are expressed consistently and independently of environmental conditions. Methods and results: Pruning weights and yield components from two independent rootstock experiments are reported. In the first experiment, the effect of two levels (30 and 70 kgN/ha/year) was studied during 15 years on Cabernet-Sauvignon vines grafted onto SO4 and Riparia Gloire de Montpellier (RGM). In the second one, Cabernet-Sauvignon and Merlot vines grafted on SO4 and RGM were submitted to two levels of soil fertility shortly after plantation: control and high (100 kgN/ha/year + irrigation) and data from the plantation to year 6 were recorded. In both experiments, vine vigour and yield were significantly affected by rootstocks and fertilisation/irrigation treatments. No interaction was recorded. The devigorating effect of RGM in comparison to SO4 was observed in both experiments, regardless of other parameters. Cabernet-Sauvignon was more affected by rootstock than Merlot. Conclusion: Rootstock effects on vine vegetative and reproductive development were consistently expressed, indicating that scion-rootstock interactions are governed not only by adaptative, but also by specific physiological traits. Significance and impact of study: This work provides information on scion-rootstock interactions which may be useful in rootstock breeding programs and may help to better choose the rootstock according to the scion and the environment

Greffadapt: a relevant experimental vineyard to speed up grapevine rootstock selection

National audienc

Greffadapt : a relevant experimental vineyard to speed up the selection of grapevine rootstock

Oral presentation. 21st GiESCO International Meeting "A multidisciplinary vision towards sustainable viticulture", 2019 Jun. 23-28, Thessaloniki, Greec