The infective cycle of Cabbage leaf curl virus (CaLCuV) is affected by CRUMPLED LEAF (CRL) gene in Arabidopsis thaliana

<p>Abstract</p> <p>Background</p> <p>Geminiviruses are single-stranded DNA viruses that cause serious crop losses worldwide. Successful infection by these pathogens depends extensively on virus-host intermolecular interactions that allow them to express their gene products, to replicate their genomes and to move to adjacent cells and throughout the plant.</p> <p>Results</p> <p>To identify host genes that show an altered regulation in response to <it>Cabbage leaf curl virus </it>(CaLCuV) infection, a screening of transposant <it>Arabidopsis thaliana </it>lines was carried out. Several genes were identified to be virus responsive and one, <it>Crumpled leaf </it>(<it>CRL) </it>gene, was selected for further characterization. <it>CRL </it>was previously reported by Asano et al., (2004) to affect the morphogenesis of all plant organs and the division of plastids. We report here that <it>CRL </it>expression, during CaLCuV infection, shows a short but strong induction at an early stage (3-5 days post inoculation, dpi). To study the role of <it>CRL </it>in CaLCuV infection, <it>CRL </it>over-expressing and silenced transgenic plants were generated. We compared the replication, movement and infectivity of CaLCuV in transgenic and wild type plants.</p> <p>Conclusion</p> <p>Our results showed that CRL over-expressing plants showed an increased susceptibility to CaLCuV infection (as compared to wt plants) whereas <it>CRL</it>-silenced plants, on the contrary, presented a reduced susceptibility to viral infection. The possible role of <it>CRL </it>in the CaLCuV infection cycle is discussed.</p

Whole-genome sequencing of cultivated and wild peppers provides insights into Capsicum domestication and specialization

As an economic crop, pepper satisfies people's spicy taste and has medicinal uses worldwide. To gain a better understanding of Capsicum evolution, domestication, and specialization, we present here the genome sequence of the cultivated pepper Zunla-1 (C. annuum L.) and its wild progenitor Chiltepin (C. annuum var. glabriusculum). We estimate that the pepper genome expanded similar to 0.3 Mya (with respect to the genome of other Solanaceae) by a rapid amplification of retrotransposons elements, resulting in a genome comprised of similar to 81% repetitive sequences. Approximately 79% of 3.48-Gb scaffolds containing 34,476 protein-coding genes were anchored to chromosomes by a high-density genetic map. Comparison of cultivated and wild pepper genomes with 20 resequencing accessions revealed molecular footprints of artificial selection, providing us with a list of candidate domestication genes. We also found that dosage compensation effect of tandem duplication genes probably contributed to the pungent diversification in pepper. The Capsicum reference genome provides crucial information for the study of not only the evolution of the pepper genome but also, the Solanaceae family, and it will facilitate the establishment of more effective pepper breeding programs

Mouse mammary tumor virus-like gene sequences are present in lung patient specimens

<p>Abstract</p> <p>Background</p> <p>Previous studies have reported on the presence of Murine Mammary Tumor Virus (MMTV)-like gene sequences in human cancer tissue specimens. Here, we search for MMTV-like gene sequences in lung diseases including carcinomas specimens from a Mexican population. This study was based on our previous study reporting that the INER51 lung cancer cell line, from a pleural effusion of a Mexican patient, contains MMTV-like <it>env </it>gene sequences.</p> <p>Results</p> <p>The MMTV-like <it>env </it>gene sequences have been detected in three out of 18 specimens studied, by PCR using a specific set of MMTV-like primers. The three identified MMTV-like gene sequences, which were assigned as INER6, HZ101, and HZ14, were 99%, 98%, and 97% homologous, respectively, as compared to GenBank sequence accession number <ext-link ext-link-id="AY161347" ext-link-type="gen">AY161347</ext-link>. The INER6 and HZ-101 samples were isolated from lung cancer specimens, and the HZ-14 was isolated from an acute inflammatory lung infiltrate sample. Two of the <it>env </it>sequences exhibited disruption of the reading frame due to mutations.</p> <p>Conclusion</p> <p>In summary, we identified the presence of MMTV-like gene sequences in 2 out of 11 (18%) of the lung carcinomas and 1 out of 7 (14%) of acute inflamatory lung infiltrate specimens studied of a Mexican Population.</p

Transcriptome analysis of symptomatic and recovered leaves of geminivirus-infected pepper (<it>Capsicum annuum</it>)

<p>Abstract</p> <p>Background</p> <p>Geminiviruses are a large and important family of plant viruses that infect a wide range of crops throughout the world. The <it>Begomovirus</it> genus contains species that are transmitted by whiteflies and are distributed worldwide causing disease on an array of horticultural crops. Symptom remission, in which newly developed leaves of systemically infected plants exhibit a reduction in symptom severity (recovery), has been observed on pepper (<it>Capsicum annuum</it>) plants infected with <it>Pepper golden mosaic virus</it> (PepGMV). Previous studies have shown that transcriptional and post-transcriptional gene silencing mechanisms are involved in the reduction of viral nucleic acid concentration in recovered tissue. In this study, we employed deep transcriptome sequencing methods to assess transcriptional variation in healthy (mock), symptomatic, and recovered pepper leaves following PepGMV infection.</p> <p>Results</p> <p>Differential expression analyses of the pepper leaf transcriptome from symptomatic and recovered stages revealed a total of 309 differentially expressed genes between healthy (mock) and symptomatic or recovered tissues. Computational prediction of differential expression was validated using quantitative reverse-transcription PCR confirming the robustness of our bioinformatic methods. Within the set of differentially expressed genes associated with the recovery process were genes involved in defense responses including pathogenesis-related proteins, reactive oxygen species, systemic acquired resistance, jasmonic acid biosynthesis, and ethylene signaling. No major differences were found when compared the differentially expressed genes in symptomatic and recovered tissues. On the other hand, a set of genes with novel roles in defense responses was identified including genes involved in histone modification. This latter result suggested that post-transcriptional and transcriptional gene silencing may be one of the major mechanisms involved in the recovery process. Genes orthologous to the <it>C. annuum</it> proteins involved in the pepper-PepGMV recovery response were identified in both <it>Solanum lycopersicum</it> and <it>Solanum tuberosum</it> suggesting conservation of components of the viral recovery response in the Solanaceae.</p> <p>Conclusion</p> <p>These data provide a valuable source of information for improving our understanding of the underlying molecular mechanisms by which pepper leaves become symptomless following infection with geminiviruses. The identification of orthologs for the majority of genes differentially expressed in recovered tissues in two major solanaceous crop species provides the basis for future comparative analyses of the viral recovery process across related taxa.</p

Whole-genome sequencing of cultivated and wild peppers provides insights into <i>Capsicum</i> domestication and specialization

As an economic crop, pepper satisfies people’s spicy taste and has medicinal uses worldwide. To gain a better understanding of Capsicum evolution, domestication, and specialization, we present here the genome sequence of the cultivated pepper Zunla-1 (C. annuum L.) and its wild progenitor Chiltepin (C. annuum var. glabriusculum). We estimate that the pepper genome expanded ∼0.3 Mya (with respect to the genome of other Solanaceae) by a rapid amplification of retrotransposons elements, resulting in a genome comprised of ∼81% repetitive sequences. Approximately 79% of 3.48-Gb scaffolds containing 34,476 protein-coding genes were anchored to chromosomes by a high-density genetic map. Comparison of cultivated and wild pepper genomes with 20 resequencing accessions revealed molecular footprints of artificial selection, providing us with a list of candidate domestication genes. We also found that dosage compensation effect of tandem duplication genes probably contributed to the pungent diversification in pepper. The Capsicum reference genome provides crucial information for the study of not only the evolution of the pepper genome but also, the Solanaceae family, and it will facilitate the establishment of more effective pepper breeding programs