title: Seed maturation in Arabidopsis thaliana is characterized by nuclear size reduction and increased chromatin condensation.
abstract: 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.
authors: Department of Plant Breeding and Genetics,  Max Planck Institute for Plant Breeding Research, 50829 Cologne,  Germany.
authors: Martijn
authors: M
authors: van Zanten
authors: Maria A
authors: MA
authors: Koini
authors: Regina
authors: R
authors: Geyer
authors: Yongxiu
authors: Y
authors: Liu
authors: Vittoria
authors: V
authors: Brambilla
authors: Dorothea
authors: D
authors: Bartels
authors: Maarten
authors: M
authors: Koornneef
authors: Paul
authors: P
authors: Fransz
authors: Wim J J
authors: WJ
authors: Soppe
mesh_terms: D000222:Adaptation, Physiological; D017360:Arabidopsis / Q000166:cytology* / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000378:metabolism; D053145:Cell Nucleus Size; D002843:Chromatin / Q000378:metabolism*; D018548:Cotyledon / Q000166:cytology; D020732:Cytogenetic Analysis; D003890:Desiccation; D057445:Plant Dormancy; D012639:Seeds / Q000166:cytology* / Q000254:growth & development*
chemical_list: D029681:Arabidopsis Proteins; D002843:Chromatin