Seed maturation in Arabidopsis is characterised by nuclear size reduction and increased chromatin condensation
Zanten, M. van; Koini, M.A. ; Geyer, R. ; Liu, Y. ; Brambilla, V. ; Bartels, D. ; Koornneef, M. ; Fransz, P. ; Soppe, W.J.J. - \ 2011
Proceedings of the National Academy of Sciences of the United States of America 108 (2011)50. - ISSN 0027-8424 - p. 20219 - 20224.
plant craterostigma-plantagineum - desiccation tolerance - gene-regulation - dormancy - germination - heterochromatin - mutants - establishment - transcription - organization
Most plant species rely on seeds for their dispersal and survival under unfavorable environmental conditions. Seeds are characterized by their low moisture content and significantly reduced metabolic activities. During the maturation phase, seeds accumulate storage reserves and become desiccation-tolerant and dormant. Growth is resumed after release of dormancy and the occurrence of favorable environmental conditions. Here we show that embryonic cotyledon nuclei of Arabidopsis thaliana seeds have a significantly reduced nuclear size, which is established at the beginning of seed maturation. In addition, the chromatin of embryonic cotyledon nuclei from mature seeds is highly condensed. Nuclei regain their size and chromatin condensation level during germination. The reduction in nuclear size is controlled by the seed maturation regulator ABSCISIC ACID-INSENSITIVE 3, and the increase during germination requires two predicted nuclear matrix proteins, LITTLE NUCLEI 1 and LITTLE NUCLEI 2. Our results suggest that the specific properties of nuclei in ripe seeds are an adaptation to desiccation, independent of dormancy. We conclude that the changes in nuclear size and chromatin condensation in seeds are independent, developmentally controlled processes
PHYTOCHROME B and HISTONE DEACETYLASE 6 Control Light-Induced Chromatin Compaction in Arabidopsis thaliana
Tessadori, F. ; Zanten, M. van; Pavlova, P. ; Clifton, R. ; Pontvianne, F. ; Snoek, L.B. ; Millenaar, F.F. ; Schulkes, R.K. ; Driel, R. van; Voesenek, L.A.C.J. ; Spillane, C. ; Pikaard, C.S. ; Fransz, P.F. ; Peeters, A.J.M. - \ 2009
Plos Genetics 5 (2009)9. - ISSN 1553-7404 - 13 p.
natural allelic variation - inbred line population - dna methylation - flowering time - genome regulation - genetic-variation - circadian clock - linkage map - h3 lysine-9 - heterochromatin
Natural genetic variation in Arabidopsis thaliana exists for many traits and often reflects acclimation to local environments. Studying natural variation has proven valuable in the characterization of phenotypic traits and, in particular, in identifying genetic factors controlling these traits. It has been previously shown that chromatin compaction changes during development and biotic stress. To gain more insight into the genetic control of chromatin compaction, we investigated the nuclear phenotype of 21 selected Arabidopsis accessions from different geographic origins and habitats. We show natural variation in chromatin compaction and demonstrate a positive correlation with latitude of geographic origin. The level of compaction appeared to be dependent on light intensity. A novel approach, combining Quantitative Trait Locus (QTL) mapping and microscopic examination, pointed at PHYTOCHROME-B (PHYB) and HISTONE DEACETYLASE-6 (HDA6) as positive regulators of light-controlled chromatin compaction. Indeed, mutant analyses demonstrate that both factors affect global chromatin organization. HDA6, in addition, strongly promotes the light-mediated compaction of the Nucleolar Organizing Regions (NORs). The accession Cape Verde Islands-0 (Cvi-0), which shows sequence polymorphism in the PHYB gene and in the HDA6 promotor, resembles the hda6 mutant in having reduced chromatin compaction and decreased methylation levels of DNA and histone H3K9 at the NORs. We provide evidence that chromatin organization is controlled by light intensity. We propose that chromatin plasticity is associated with acclimation of Arabidopsis to its environment. The polymorphic alleles such as PHYB and HDA6 control this process
Map - vs. homology - based cloning for the recessive gene ol-2 conferring resistance to tomato powdery mildew
Pavan, S.N.C. ; Zheng, Z. ; Borisova, M. ; Berg, P.M.M.M. van den; Lotti, C. ; Giovanni, C. de; Lindhout, P. ; Jong, J.H. de; Ricciardi, L. ; Visser, R.G.F. ; Bai, Y. - \ 2008
Euphytica 162 (2008)1. - ISSN 0014-2336 - p. 91 - 98.
oidium-neolycopersici - lycopersicon-esculentum - rflp analysis - markers - locus - aflp - heterochromatin - identification - defense - plants
The recessive gene ol-2 confers papilla-associated and race-non-specific resistance to tomato powdery mildew caused by Oidium neolycopersici. In order to facilitate marker assisted selection (MAS) in practical breeding programmes, we identified two simple sequence repeat (SSR) markers and one cleaved amplified polymorphic sequence (CAPS) marker which are linked to the resistance locus and co-dominantly inherited. Aiming to provide a base for ol-2 positional cloning, we used a large segregating F2 population to merge these markers with all the ol-2 linked amplified fragment length polymorphism (AFLP®) markers previously identified in an integrated genetic map. By screening a tomato bacterial artificial chromosome (BAC) library, we detected two BAC clones containing two expressed sequence tags (ESTs) homologous to the gene mlo, responsible for powdery mildew resistance in barley, as well as an ol-2-linked marker. Chromosomal mapping by Fluorescence in situ Hybridization (FISH) revealed major signals of the two BAC DNAs in the pericentromeric heterochromatin of the short arm of chromosome 4, in the same region where the ol-2 gene was previously mapped. The genetic and cytogenetic co-localisation between ol-2 and tomato mlo-homologue(s), in addition to the similarity of ol-2 and mlo resistances for both genetic and phytopathological characteristics, suggests that ol-2 is likely a mlo-homologue. Thus, a homology-based cloning approach could be more suitable than positional cloning for ol-2 isolation.
Characterisation of distant Alstroemeria hybrids: application of highly repetitive DNA sequences from A. ligtu spp. ligtu
Shujun Zhou, ; Jeu, M.J. de; Visser, R.G.F. ; Kuipers, A.G.J. - \ 2003
Annals of Applied Biology 142 (2003)3. - ISSN 0003-4746 - p. 277 - 283.
in-situ hybridization - molecular cytogenetics - interspecific hybrids - physical organization - ovule culture - sequences - heterochromatin - localization - family - aurea
Clones from a Sau3A family of eight highly repetitive sequences previously isolated from a genomic DNA library of Alstroemeria ligtu ssp. ligtu were sequenced and found to be highly conserved. A trinucleotide microsatellite repeat [GCA](3-4) was present. A second, unrelated, Sau3A repeat was also characterised. Southern analysis proved that the isolated repeats were specific for the A. ligtu subspecies and could not be detected in other Chilean or Brazilean Alstroemeria species. As shown by in situ hybridisation, the Sau3A family and the unrelated Sau3A repeat co-localised at distinct sites along most chromosomes of Alstroemeria ligtu ssp. ligtu and Alstroemeria ligtu ssp. simsii. The present set of species-specific repetitive sequences enables the identification of A. ligtu chromosomes, and thus the tracking of chromosome transmission to interspecific hybrids and their progeny.
Molecular characterization and physical localization of highly repetitive DNA sequences from Brazilian Alstroemeria species
Kuipers, A.G.J. ; Kamstra, S.A. ; Jeu, M.J. de; Jacobsen, E. - \ 2002
Chromosome Research 10 (2002)5. - ISSN 0967-3849 - p. 389 - 398.
in-situ hybridization - distant hybrid - heterochromatin - cytogenetics - genomes - family
Highly repetitive DNA sequences were isolated from genomic DNA libraries of Alstroemeria psittacina and A. inodora. Among the repetitive sequences that were isolated, tandem repeats as well as dispersed repeats could be discerned. The tandem repeats belonged to a family of interlinked Sau3A subfragments with sizes varying from 68-127 bp, and constituted a larger HinfI repeat of approximately 400 bp. Southern hybridization showed a similar molecular organization of the tandem repeats in each of the Brazilian Alstroemeria species tested. None of the repeats hybridized with DNA from Chilean Alstroemeria species, which indicates that they are specific for the Brazilian species. In-situ localization studies revealed the tandem repeats to be localized in clusters on the chromosomes of A. inodora and A. psittacina: distal hybridization sites were found on chromosome arms 2PS, 6PL, 7PS, 7PL and 8PL, interstitial sites on chromosome arms 2PL, 3PL, 4PL and 5PL. The applicability of the tandem repeats for cytogenetic analysis of interspecific hybrids and their role in heterochromatin organization are discussed.