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La Tour-du-Pin, France

Chen K.,Institute Of Biologie Moleculaire Des Plantes Du C N R S | Dorlhac De Borne F.,Imperial Tobacco Bergerac | Szegedi E.,Research Institute for Viticulture and Enology | Otten L.,Institute Of Biologie Moleculaire Des Plantes Du C N R S
Plant Journal | Year: 2014

Nicotiana species carry cellular T-DNA sequences (cT-DNAs), acquired by Agrobacterium-mediated transformation. We characterized the cT-DNA sequences of the ancestral Nicotiana tabacum species Nicotiana tomentosiformis by deep sequencing. N. tomentosiformis contains four cT-DNA inserts derived from different Agrobacterium strains. Each has an incomplete inverted-repeat structure. TA is similar to part of the Agrobacterium rhizogenes 1724 mikimopine-type T-DNA, but has unusual orf14 and mis genes. TB carries a 1724 mikimopine-type orf14-mis fragment and a mannopine-agropine synthesis region (mas2-mas1-ags). The mas2′ gene codes for an active enzyme. TC is similar to the left part of the A. rhizogenes A4 T-DNA, but also carries octopine synthase-like (ocl) and c-like genes normally found in A. tumefaciens. TD shows a complex rearrangement of T-DNA fragments similar to the right end of the A4 TL-DNA, and including an orf14-like gene and a gene with unknown function, orf511. The TA, TB, TC and TD insertion sites were identified by alignment with N. tabacum and Nicotiana sylvestris sequences. The divergence values for the TA, TB, TC and TD repeats provide an estimate for their relative introduction times. A large deletion has occurred in the central part of the N. tabacum cv. Basma/Xanthi TA region, and another deletion removed the complete TC region in N. tabacum. Nicotiana otophora lacks TA, TB and TD, but contains TC and another cT-DNA, TE. This analysis, together with that of Nicotiana glauca and other Nicotiana species, indicates multiple sequential insertions of cT-DNAs during the evolution of the genus Nicotiana. © 2014 John Wiley & Sons Ltd. Source


Julio E.,Imperial Tobacco Bergerac | Cotucheau J.,Imperial Tobacco Bergerac | Decorps C.,Imperial Tobacco Bergerac | Volpatti R.,Imperial Tobacco Bergerac | And 3 more authors.
Plant Molecular Biology Reporter | Year: 2015

Potato virus Y (PVY), the type member of the genus Potyvirus, is transmitted by aphids and can cause severe damage in several solanaceous family crops. In Nicotiana tabacum, a large genome deletion conferring resistance to PVY, the va gene, is commonly used. This resistance is unfortunately associated with lower tobacco quality parameters, potentially due to the presence of several other important genes in the deleted region. In the present study, we have used next-generation sequencing to analyze the transcriptome of a dozen of tobacco F7 recombinant inbred lines (RILs) segregating for PVY resistance. After comparison with a reference transcriptome, genes differentially expressed between resistant and susceptible plants were identified. About 30 candidate sequences were selected, including a sequence annotated as encoding an eukaryotic translation initiation factor 4E (eIF4E), which was strongly expressed in susceptible plants but not in resistant ones. Other differentially expressed candidates are mostly related to photosynthesis. A complete correlation between susceptibility and expression of this eIF4E sequence was confirmed by amplification in 91 F8 RILs and in a segregating F2 population. The gene was mapped on chromosome 21 of the tobacco genetic map and corresponds to an eIF4E isoform derived from the N. sylvestris parent of tobacco. Final confirmation of the identification of the va gene came from the analysis of two tobacco lines with missense mutations in the eIF4E gene and which correspondingly showed resistance to PVY infection. Screening of a large collection of tobacco accessions revealed a strong correlation between the status of this eIF4 gene and PVY resistance, but the identification of a few resistant accessions with an apparently intact gene suggests the possible existence of alternative resistance sources. The identification of the va gene and of molecular markers linked to it or to the large deletion associated with it opens the way to breeding efforts aimed at breaking the linkage drag associated with this valuable resistance gene. © 2014, Springer Science+Business Media New York. Source


Hermand V.,French National Institute for Agricultural Research | Julio E.,Imperial Tobacco Bergerac | Dorlhac De Borne F.,Imperial Tobacco Bergerac | Punshon T.,Dartmouth College | And 4 more authors.
Metallomics | Year: 2014

Cadmium (Cd) is a non-essential heavy metal, which is classified as a "known human carcinogen" by the International Agency for Research on Cancer (IARC). Understanding the mechanisms controlling Cd distribution in planta is essential to develop phytoremediation approaches as well as for food safety. Unlike most other plants, tobacco (Nicotiana tabacum) plants translocate most of the Cd taken up from the soil, out of the roots and into the shoots, leading to high Cd accumulation in tobacco shoots. Two orthologs of the Arabidopsis thaliana HMA2 and HMA4 Zn and Cd ATPases that are responsible for zinc (Zn) and Cd translocation from roots to shoots were identified in tobacco and sequenced. These genes, named NtHMAα and NtHMAβ, were more highly expressed in roots than in shoots. NtHMAα was expressed in the vascular tissues of both roots and leaves as well as in anthers. No visual difference was observed between wild-type plants and plants in which the NtHMAα and NtHMAβ genes were either mutated or silenced. These mutants showed reduced Zn and Cd accumulation in shoots as well as increased Cd tolerance. When both NtHMA genes were silenced, plant development was altered and pollen germination was severely impaired due to Zn deficiency. Interestingly, seeds from these lines also showed decreased Zn concentration but increased iron (Fe) concentration. This journal is © the Partner Organisations 2014. Source

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