Elliptic grids, rational functions, and the Pad\'e interpolation

International audienceProcedures are now available for the exploitation of protoplast technology for the genetic manipu- lation of lettuce and for studies of lettuce/virus interactions. These techniques have made it possible to overcome interspecific barriers by protoplast fusion. Following the procedures we developed, we were able to obtain hybrids between Lactuca sativa and two wild Lactuca species (L. tatarica and L. perennis). Moreover, protoplast technology can overcome some of the limitations in the application of mutation techniques in crops. In this paper, we demonstrated the feasibility and the power of our in vitro techni- ques, in combination with induced mutations, for creating new variability in lettuce. Furthermore, we adapted protocols that can provide the opportunity to start studies on mechanisms associated with the different LMV-resistance genes at the cellular level. It is presently possible to obtain protoplasts from different Lactuca species containing different resistance genes. A protocol for specific staining by immu- nofluorescence of infected lettuce protoplasts is described and preliminary electroporation experiments in some Lactuca protoplasts were performed

Interest of protoplasts for lettuce breeding

International audienceProcedures are now available for the exploitation of protoplast technology for the genetic manipu- lation of lettuce and for studies of lettuce/virus interactions. These techniques have made it possible to overcome interspecific barriers by protoplast fusion. Following the procedures we developed, we were able to obtain hybrids between Lactuca sativa and two wild Lactuca species (L. tatarica and L. perennis). Moreover, protoplast technology can overcome some of the limitations in the application of mutation techniques in crops. In this paper, we demonstrated the feasibility and the power of our in vitro techni- ques, in combination with induced mutations, for creating new variability in lettuce. Furthermore, we adapted protocols that can provide the opportunity to start studies on mechanisms associated with the different LMV-resistance genes at the cellular level. It is presently possible to obtain protoplasts from different Lactuca species containing different resistance genes. A protocol for specific staining by immu- nofluorescence of infected lettuce protoplasts is described and preliminary electroporation experiments in some Lactuca protoplasts were performed

Comparaison des propriétés biologiques et de la variabilité moléculaire du virus de la mosaïque de la laitue (LMV)

National audienc

Mapping of the virulence determinants in lettuce mosaic virus spontaneous variants

International audienc

Cartographie des déterminants de l'agressivité et de la virulence du virus de la mosaïque de la laitue

International audienc

Use of infectious cDNA to study the pathogenicity of lettuce mosaic potyvirus (LMV)

International audienc

Coat protein gene-mediated protection in Lactuca sativa against lettuce mosaic potyvirus strains

International audienceLettuce mosaic potyvirus (LMV) can be very destructive on lettuce crops worldwide. The LMV strain 0 (LMV-0) coat protein (CP) gene was engineered for expression in plants. It was introduced into three susceptible cultivars of Lactuca sativa using an improved procedure for transformation and regeneration of lettuce, by co-cultivation of leaf explants with Agrobacterium tumefaciens. Several transformants accumulated detectable levels of LMV CP. The R1 progeny of twelve RO transformants (four plants per cultivar) with T-DNA integration at one single locus, was studied for protection against LMV. The progeny from five RO transformants showed resistance to LMV-0, with the effectiveness of resistance depending on the development stage of the plants at the time of inoculation. The R1 and R2 progeny from one of these RO transformants, Cocarde-9a, were more extensively analysed. The homozygous but not the hemizygous R1 plants displayed protection to LMV-0. The R2 progeny from one homozygous R1 plant were shown to be resistant to infection by LMV-0 and other LMV strains. As previously observed in other cases of potyvirus sequence-mediated protection, a phenomenon of recovery was observed in some plants, as well as complete resistance. However, this recovery phenotype was not always maintained, as opposed to the previous described cases, leading to a late progression of viral infection

Nucleotide sequence of the 3'terminal region of the genome of four Lettuce mosaic virus isolates from Greece and Yemen

International audience Lettuce mosaic virus (LMV) is an economically important Potyvirus causing a severe disease of commercial lettuce crops. Based on molecular data, three phylogenetic groups of isolates have previously been discriminated, reflecting their geographical origin (Western Europe-California, Greece, or Yemen). Sequence information for the entire coat protein domain was only available for one of the Western Europe-California phylogenetic group. We have now sequenced the 3′ terminal region of the genome LMV-Gr4, -Gr5 and -GrB, isolates which belong to the Greek phylogenetic group and of LMV-Yar, the sole known representative of the third LMV phylogenetic group. The region sequenced encodes the last 62 amino-acids of the polymerase and the entire coat protein of the four isolates, plus the 3′ non-translated region of LMV-Gr5 and -Yar. The Greek and Yemenite isolates studied are all very aggressive on lettuce, are able to overcome the resistance genes mo1 1 and mo1 2 and belong to the two phylogenetic groups which have so far been only partially characterised. As for other Potyviruses, the core and the C-terminal regions of the coat protein are highly conserved among all isolates whereas the N-terminus is more variable. No amino acid change in the coat protein or carboxy-terminal part of the polymerase could be related to the resistance-breaking properties of the isolates analysed. The sequences obtained provide the basis for the rapid typing of LMV isolates using the restriction pattern of segments of cDNA amplified by PCR

Résistance vis-à-vis des souches de LMV, dans des laitues transgéniques exprimant la protéine capsidiale du LMV

National audienc

Caracterizaçao preliminar de isolados de sequivirus inectando alface na America do Sul e Europa

International audienc