Biomedical subjects

Karolina Tandre

Publications and source records attributed to Karolina Tandre.

4 recordsLinked to original sources

PubMed2004

A Populus EST resource for plant functional genomics.

Trees present a life form of paramount importance for terrestrial ecosystems and human societies because of their ecological structure and physiological function and provision of energy and industrial materials. The genus Populus is the internationally accepted model for molecular tree biology. We have analyzed 102,019 Populus ESTs that clustered into 11,885 clusters and 12,759 singletons. We also provide >4,000 assembled full clone sequences to serve as a basis for the upcoming annotation of the Populus genome sequence. A public web-based EST database (POPULUSDB) provides digital expression profiles for 18 tissues that comprise the majority of differentiated organs. The coding content of Populus and Arabidopsis genomes shows very high similarity, indicating that differences between these annual and perennial angiosperm life forms result primarily from differences in gene regulation. The high similarity between Populus and Arabidopsis will allow studies of Populus to directly benefit from the detailed functional genomic information generated for Arabidopsis, enabling detailed insights into tree development and adaptation. These data will also valuable for functional genomic efforts in Arabidopsis.

Ecosystem↗

PubMed2004

A transcriptional timetable of autumn senescence.

BACKGROUND: We have developed genomic tools to allow the genus Populus (aspens and cottonwoods) to be exploited as a full-featured model for investigating fundamental aspects of tree biology. We have undertaken large-scale expressed sequence tag (EST) sequencing programs and created Populus microarrays with significant gene coverage. One of the important aspects of plant biology that cannot be studied in annual plants is the gene activity involved in the induction of autumn leaf senescence. RESULTS: On the basis of 36,354 Populus ESTs, obtained from seven cDNA libraries, we have created a DNA microarray consisting of 13,490 clones, spotted in duplicate. Of these clones, 12,376 (92%) were confirmed by resequencing and all sequences were annotated and functionally classified. Here we have used the microarray to study transcript abundance in leaves of a free-growing aspen tree (Populus tremula) in northern Sweden during natural autumn senescence. Of the 13,490 spotted clones, 3,792 represented genes with significant expression in all leaf samples from the seven studied dates. CONCLUSIONS: We observed a major shift in gene expression, coinciding with massive chlorophyll degradation, that reflected a shift from photosynthetic competence to energy generation by mitochondrial respiration, oxidation of fatty acids and nutrient mobilization. Autumn senescence had much in common with senescence in annual plants; for example many proteases were induced. We also found evidence for increased transcriptional activity before the appearance of visible signs of senescence, presumably preparing the leaf for degradation of its components.

Aging↗

PubMed2004

The MADS-box gene DAL1 is a potential mediator of the juvenile-to-adult transition in Norway spruce (Picea abies).

Progression through the plant life cycle involves change in many essential features, most notably in the capacity to reproduce. The transition from a juvenile vegetative and non-reproductive to an adult reproductive phase is gradual and can take many years; in the conifer Norway spruce, Picea abies, typically 20-25 years. We present a detailed analysis of the activities of three regulatory genes with potential roles in this transition in Norway spruce: DAL1, a MADS-box gene related to the AGL6 group of genes from angiosperms, and the two LEAFY-related genes PaLFY and PaNLY. DAL1 activity is initiated in the shoots of juvenile trees at an age of 3-5 years, and then increases with age, whereas both LFY genes are active throughout the juvenile phase. The activity of DAL1 further shows a spatial pattern along the stem of the tree that parallels a similar gradient in physiological and morphological features associated with maturation to the adult phase. Constitutive expression of DAL1 in transgenic Arabidopsis plants caused a dramatic attenuation of both juvenile and adult growth phases; flowers forming immediately after the embryonic phase of development in severely affected plants. Taken together, our results support the notion that DAL1 may have a regulatory role in the juvenile-to-adult transition in Norway spruce.

Arabidopsis↗

PubMedDate not supplied

The DAL10 gene from Norway spruce (Picea abies) belongs to a potentially gymnosperm-specific subclass of MADS-box genes and is specifically active in seed cones and pollen cones.

Transcription factors encoded by different members of the MADS-box gene family have evolved central roles in the regulation of reproductive organ development in the flowering plants, the angiosperms. Development of the stamens and carpels, the pollen- and seed-bearing organs, involves the B- and C-organ-identity MADS-box genes. B- and C-type gene orthologs with activities specifically in developing pollen- and seed-bearing organs are also present in the distantly related gymnosperms: the conifers and the gnetophytes. We now report on the characterization of DAL10, a novel MADS-box gene from the conifer Norway spruce, which unlike the B- and C-type conifer genes shows no distinct orthology relationship to any angiosperm gene or clade in phylogenetic analyses. Like the B- and C-type genes, it is active specifically in developing pollen cones and seed cones. In situ RNA localization experiments show DAL10 to be expressed in the cone axis, which carry the microsporophylls of the young pollen cone. In contrast, in the seed cone it is expressed both in the cone axis and in the bracts, which subtend the ovuliferous scales. Expression data and the phenotype of transgenic Arabidopsis plants expressing DAL10 suggest that the gene may act upstream to or in concert with the B- and C-type genes in the establishment of reproductive identity of developing cones.

Base Sequence↗