An upper limit of the ratio of DNA volume to nuclear volume exists in plants

Fujimoto, Shinsaku; Ito, Makoto; Matsunaga, Sachihiro; Fukui, Kiichi

doi:10.1266/ggs.80.345

Cited by 23 publications

(23 citation statements)

References 23 publications

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“…Our results demonstrate that the linc1-1 linc2-1 mutation combination increases the chromatin packaging ratio: DNA content per unit of nuclear volume. This phenotype is particularly intriguing in light of studies demonstrating that there is a fixed relationship between DNA content and nuclear volume that applies to a range of plant species with genome sizes spanning >2 orders of magnitude (Fujimoto et al, 2005;Jovtchev et al, 2006). Despite violating this fixed chromatin packaging ratio, the linc1 and linc2 single mutants do not exhibit abnormal developmental phenotypes.…”

Section: Discussionmentioning

confidence: 97%

LITTLE NUCLEIGenes Affecting Nuclear Morphology inArabidopsis thaliana

et al. 2007

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Efforts to understand nuclear organization in plant cells have received little assistance from the better-studied animal nuclei, because plant proteomes do not contain recognizable counterparts to the key animal proteins involved in nuclear organization, such as lamin nuclear intermediate filament proteins. Previous studies identified a plant-specific insoluble nuclear protein in carrot (Daucus carota), called Nuclear Matrix Constituent Protein1 (NMCP1), which contains extensive coiled-coil domains and localizes to the nuclear periphery. Here, we describe a genetic characterization of two NMCP1-related nuclear proteins in Arabidopsis thaliana, LITTLE NUCLEI1 (LINC1) and LINC2. Disruption of either gene caused a reduction in nuclear size and altered nuclear morphology. Moreover, combining linc1 and linc2 mutations had an additive effect on nuclear size and morphology but a synergistic effect on chromocenter number (reduction) and whole-plant morphology (dwarfing). The reduction in nuclear size in the linc1 linc2 double mutant was not accompanied by a corresponding change in endopolyploidy. Rather, the density of DNA packaging at all endopolyploid levels in the linc1 linc2 mutants was increased significantly. Our results indicate that the LINC coiled-coil proteins are important determinants of plant nuclear structure.

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Section: Discussionmentioning

confidence: 97%

LITTLE NUCLEIGenes Affecting Nuclear Morphology inArabidopsis thaliana

et al. 2007

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“…A nucleus of a given size cannot contain an unlimited amount of DNA; Fujimoto et al (35) reported an upper limit of 3% for the ratio of DNA volume to nuclear volume by comparing root tip cells across plant species with different genome sizes. In Arabidopsis embryonic cotyledon nuclei with reduced size at 20 DAP, this ratio does not exceed 1%, which is well below the upper limit found in plants but above the value of 0.26% reported by Fujimoto et al (35) in Arabidopsis root tip cells. This confirms that the chromatin in these reduced nuclei is highly compacted.…”

Section: Discussionmentioning

confidence: 99%

Seed maturation in Arabidopsis thaliana is characterized by nuclear size reduction and increased chromatin condensation

Zanten

Koini

Geyer

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

152

135

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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.seed development | seed imbibition | seed germination | chromatin organization P lant seeds represent a quiescent dehydrated state with significantly reduced metabolic activities, which renders them resistant to abiotic stresses and viable for years. Germination occurs when nondormant seeds meet permissive environmental conditions for humidity, light, and temperature. Seed dormancy evolved to postpone germination during unfavorable seasons (1-3). The moisture content of ripe seeds from the model plant Arabidopsis thaliana is <10% (4). Low humidity levels can cause cellular damage due to protein unfolding and membrane disturbance. Sugars, late embryogenesis abundant proteins, and heat shock proteins play important roles in preventing this damage in seeds (5).Dehydration, accumulation of storage reserves, and induction of dormancy occur during the seed maturation phase, which is initiated after the embryo has fully developed (4). In Arabidopsis, seed maturation is tightly controlled by at least four central regulators, ABSCISIC ACID-INSENSITIVE 3 (ABI3), LEAFY COTYLEDON 1 (LEC1), LEC2, and FUSCA 3 (FUS3) (3, 6, 7). Other proteins have more dedicated roles in one of these processes; for instance, DELAY OF GERMINATION 1 (DOG1) and HISTONE MONOUBIQUITINATION 1 (HUB1) are required only for the establishment of seed dormancy (8, 9).Dry seeds represent a transitional state between embryo and seedling. During a phase transition, genes that control the "new" state need to be activated, whereas genes required for the "old" state must be repressed. Chromatin compaction in the cell nucleus has been proposed to contribute to gene regulation by allowing differential accessibility of DNA for the transcription machinery (10, 11). Accordingly, developmental changes in the plant are often ...

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“…This type of chromosome distribution is well known for mammalian chromosomes and is referred to as chromosome territory [Cremer and Cremer, 2001]. Fujimoto et al [2005] demonstrated that plants show 3 types of nuclear structures based on their genome sizes (small: 1 ! 10 4 Mb or less, large: 1 !…”

Section: Correspondence Between Chromosome and Genetic Mapsmentioning

confidence: 99%

Structural Analyses of Chromosomes and Their Constituent Proteins

Fukui

2009

Cytogenet Genome Res

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The importance of chromosome structural study is first described. Then an overview of historical imaging methods that enable us to quantitatively understand chromosome images and structure is given with special reference to the identification of small plant chromosomes and development of their quantitative chromosome maps. A three-dimensional understanding of chromosome distribution within a nucleus answers why the gene-rich regions localize at both ends of chromosomes, especially in the case of species with Rabl orientation. Not only imaging methods but also proteomic approaches are effective in understanding chromosome structure. Over 200 proteins have been identified by proteome analysis of human metaphase chromosomes, and are categorized into four distinct groups according to their nature and localization on chromosomes. These are chromosome coating proteins (CCPs), chromosome peripheral proteins (CPPs), chromosome structural proteins (CSPs), and chromosome fibrous proteins (CFPs). A chromosome four layer model has been developed accordingly. Case studies on individual identified proteins are further described, and the functional similarities of CPPs are exemplified. In addition the controversial roles of CSPs (topoisomerase and condensin), especially for development of higher-order chromosome structure, are discussed. Finally, it is concluded that further advances in chromosome research are necessary to solve an enigma lasting nearly two centuries, that is, why chromosomes retain the same shape in plants and animals.

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An upper limit of the ratio of DNA volume to nuclear volume exists in plants

Cited by 23 publications

References 23 publications

LITTLE NUCLEIGenes Affecting Nuclear Morphology inArabidopsis thaliana

LITTLE NUCLEIGenes Affecting Nuclear Morphology inArabidopsis thaliana

Seed maturation in Arabidopsis thaliana is characterized by nuclear size reduction and increased chromatin condensation

Structural Analyses of Chromosomes and Their Constituent Proteins

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