Differential Dynamics of Transposable Elements during Long-Term Diploidization of Nicotiana Section Repandae (Solanaceae) Allopolyploid Genomes

PubMed ID: 23185607This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

Phoma stem canker disease on oilseed rape (Brassica napus) in China is caused by Leptosphaeria biglobosa ‘brassicae’

This document is the Accepted Manuscript version of the following article: Ze Liu, Akinwunmi O. Latunde-Dada, Avice M. Hall, Bruce D. L. Fitt, ‘Phoma stem canker disease on oilseed rape (Brassica napus) in China is caused by Leptosphaeria biglobosa ‘brassicae’’, European Journal of Plant Pathology, Vol. 140(4): 841-857, December 2014. The final publication is available at Springer via: http://dx.doi.org/10.1007/s10658-014-0513-7 © Koninklijke Nederlandse Planteziektenkundige Vereniging 2014Phoma stem canker of oilseed rape (Brassica napus) is a globally important disease that is caused by the sibling ascomycete species Leptosphaeria maculans and L. biglobosa. Sixty fungal isolates obtained from oilseed rape stems with phoma stem canker disease symptoms collected from four provinces in China in 1999, 2005 and 2006 were all identified as Leptosphaeria biglobosa, not L. maculans, by PCR diagnostics based on species-specific primers. There were no differences in cultural characteristics (e.g. pigmentation and in vitro growth) between these L. biglobosa isolates from China and those of 37 proven L. biglobosa isolates from Europe or Canada. In studies using amplified fragment length polymorphism (AFLP) markers, Chinese L. biglobosa populations were genetically more similar to European L. biglobosa populations than to the more diverse Canadian L. biglobosa populations. Sequencing of gene fragments of β-tubulin, actin and the internal transcribed spacer (ITS) region of rDNA from L. biglobosa isolates from China, Europe, Australia and Canada showed a closer taxonomic similarity of Chinese L. biglobosa to the European L. biglobosa ‘brassicae’ than to Canadian L. biglobosa ‘canadensis’ or to the Australian L. biglobosa ‘occiaustralensis’ or ‘australensis’ subclades. These results suggest that the Chinese L. biglobosa population in this study is in the same subclade as European L. biglobosa ‘brassicae’ populationsPeer reviewe

Retrotransposon vectors for gene delivery in plants

<p>Abstract</p> <p>Background</p> <p>Retrotransposons are abundant components of plant genomes, and although some plant retrotransposons have been used as insertional mutagens, these mobile genetic elements have not been widely exploited for plant genome manipulation. In vertebrates and yeast, retrotransposons and retroviruses are routinely altered to carry additional genes that are copied into complementary (c)DNA through reverse transcription. Integration of cDNA results in gene delivery; recombination of cDNA with homologous chromosomal sequences can create targeted gene modifications. Plant retrotransposon-based vectors, therefore, may provide new opportunities for plant genome engineering.</p> <p>Results</p> <p>A retrotransposon vector system was developed for gene delivery in plants based on the Tnt1 element from <it>Nicotiana tabacum</it>. Mini-Tnt1 transfer vectors were constructed that lack coding sequences yet retain the 5' and 3' long terminal repeats (LTRs) and adjacent <it>cis </it>sequences required for reverse transcription. The internal coding region of Tnt1 was replaced with a neomycin phosphotransferase gene to monitor replication by reverse transcription. Two different mini-Tnt1 s were developed: one with the native 5' LTR and the other with a chimeric 5' LTR that had the first 233 bp replaced by the CaMV 35 S promoter. After transfer into tobacco protoplasts, both vectors undergo retrotransposition using GAG and POL proteins provided in <it>trans </it>by endogenous Tnt1 elements. The transposition frequencies of mini-Tnt1 vectors are comparable with native Tnt1 elements, and like the native elements, insertion sites are within or near coding sequences. In this paper, we provide evidence that template switching occurs during mini-Tnt1 reverse transcription, indicating that multiple copies of Tnt1 mRNA are packaged into virus-like particles.</p> <p>Conclusions</p> <p>Our data demonstrate that mini-Tnt1 vectors can replicate efficiently in tobacco cells using GAG and POL proteins provided in <it>trans </it>by native Tnt1 elements. This suggests that helper Tnt1 constructs can be developed to enable a Tnt1-based two-component vector system that could be used in other plant species. Such a vector system may prove useful for gene delivery or the production of cDNA that can serve as a donor molecule for gene modification through homologous recombination.</p

Etude génétique de deux interactions race-cultivar chez le pathosystème Leptosphaeria maculans (Brassica napus)

* INRA, centre de Versailles, unité de pathologie végétale 78026 Versailles Diffusion du document : INRA, centre de Versailles, unité de pathologie végétale 78026 Versailles Diplôme : Dr. d'Universiténon disponibleLeptosphaeria maculans est un ascomycete filamenteux responsable de la necrose du collet des cruciferes, maladie dommageable sur colza (brassica napus l. ). Depuis peu, des interactions specifiques sont decrites sur les cultivars de colza westar, quinta et glacier, discriminant les souches de l. Maculans en 3 pathogenicity groups (pg). Cette etude s'est proposee, en un premier temps, de caracteriser le determinisme genetique de deux interactions tant du cote de l'agent pathogene que de la plante. Par une analyse de tetrades, deux genes d'avirulence, avrlm1 et avrlm2, responsables des interactions incompatibles pg3-quinta et pg2-glacier sont mis en evidence. En parallele, l'analyse des descendances issues des croisements entre quinta, glacier et un cultivar sensible indique la presence de loci majeurs dominants de resistance, rlm1 et rlm2, correspondants a avrlm1 et avrlm2. Ces resultats demontrent pour la premiere fois chez le pathosysteme l. Maculans/b. Napus l'existence de relations gene-pour-gene. Dans un second temps, l'efficacite des resistances de quinta et glacier a ete eprouvee en conditions naturelles durant deux annees consecutives. Le bon niveau de resistance de quinta est correle a la predominance des souches pg3 dans la population locale du parasite. A l'oppose, la sensibilite de glacier est expliquee par l'absence de souches pg2. Enfin, en vue du clonage ulterieur du gene d'avirulence avrlm1 par marche chromosomique, une carte genetique de l. Maculans a ete initiee. La segregation d'avrlm1, mat, spp et 89 marqueurs rapd a ete examinee chez 88 descendants en vrac. Un groupe de liaison majeur associe avrlm1 avec 4 autres marqueurs, ad1-1,52 et j19-1,20 encadrant le locus a 4,8 cm et 1,5 cm. En complement, pour faire coincider a terme les cartes genetique et physique, les caryotypes des souches parentales ont ete etablis par pfge. L'hybridation de ad1-1,52 sur les electrocaryotypes suggere qu'avrlm1 est porte par le chromosome v du parent pg

Genetic characterization of AvrLm1, the first avirulence gene of Leptosphaeria maculans

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Tansley review Hebeloma cylindrosporum -a model species to study ectomycorrhizal symbiosis from gene to ecosystem

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