Project description:Seed dormancy in Arabidopsis is known to be mediated by the interaction of maternal and zygotic genomes during seed maturation. While studies have revealed the extensive influence of maternal processes on dormancy and germination, less is known about the influence of the father. Here we exploit differences in ploidy to explore the role of the paternal genome on progeny seed dormancy. We show that paternal genome acts to reduce seed dormancy regardless of maternal genome dose, resulting in lower dormancy in tetraploid Arabidopsis versus genetically identical diploids. We show that this paternal effect requires synthesis of RNA Polymerase IV-dependent RNAs in the male gametophyte which oppose the dormancy- inducing effects of maternal siRNAs on seed coat and endosperm development. We conclude that the paternal genome has evolved to subvert the dormancy-inducing role of the mother plant in progeny seeds.
Project description:We investigated RNA involved in the maternal control of progeny seed dormancy. Basically, we grew Ler wild type plants at 22 and 16 degree Celsius before fertilization which were moved to 22 degree for seed maturation along with ft-1 plants at 22 degree through lifetime (which show decreased seed germinability). Various RNA fractions were prepared from developing siluqes (seeds removed) and seeds, and sequenced to identify genes involved in transducing maternal memory of temperature to progeny seeds.
Project description:Maternal environment is an important regultor of seed dormancy, but the mechanisms underlying the process are poorly understood. We have found that genes in the circadian clock control dormancy, in part through their regulation of the canonical photoperiod pathway known from research into flowering time control. In this experiment we compare the affects of altering seed maturation temperature or maternal photoperiod on dry seed transcriptomes, and the photoperiod-insenstive ft-1 mutant to wt type Ler. In this way we are identifying gene expression programmes which result from the seed's response to maternal environmental experience. Keywords: Expression profilling by array 12 samples were used in this experiment
Project description:Maternal environment is an important regultor of seed dormancy, but the mechanisms underlying the process are poorly understood. We have found that genes in the circadian clock control dormancy, in part through their regulation of the canonical photoperiod pathway known from research into flowering time control. In this experiment we compare the affects of altering seed maturation temperature or maternal photoperiod on dry seed transcriptomes, and the photoperiod-insenstive ft-1 mutant to wt type Ler. In this way we are identifying gene expression programmes which result from the seed's response to maternal environmental experience. Keywords: Expression profilling by array
Project description:Seed maturation, dormancy and germination are distinct physiological processes. Transition from maturation to dormancy, and from dormancy into germination are not only critical developmental phases in the plant life cycle but are also important agricultural traits. These developmental processes and their phase transitions are fine determined and coordinately regulated by genetic makeup and environmental cues. SCARECROW-LIKE15 (SCL15) has been demonstrated to be essential for repressing the seed maturation programme in vegetative tissues (Gao et al., Nat Commun, 2015, 6:7243). Here we report that SCL15 is also important for seed dormancy maintenance, germination timing and seed vigor performance based on the effects of SCL15 mutation on plant germination, growth and reproduction when compared with wild type Arabidopsis and over-expression lines 35S:SCL15 and Napin:SCL15. Seed dormancy is enhanced by the mutation of SCL15 in a GA signaling dependent way, indicating that SCL15 plays a negative role for primary dormancy release. Seed germination is positively regulated by SCL15 through interaction with ABA, GA and auxin signaling. SCL15 acts as positive regulator of seed vigor and effect of SCL15 mRNA abundance on seed reserve accumulation and seed development during late embryogenesis may contribute to the seed vigor performance.
Project description:Mother plants play an important role in the control of dormancy and dispersal characters of their progeny. In Arabidopsis seed dormancy is imposed by the embryo-surrounding tissues of the endosperm and seed coat. Here we show that VERNALIZATION5/VIN3-LIKE 3 (VEL3) maintains maternal control over progeny seed dormancy by establishing an epigenetic state in the central cell that primes the depth of primary seed dormancy later established during seed maturation. VEL3 colocalizes with MSI1 in the nucleolus and associates with a histone deacetylase complex. Furthermore, VEL3 preferentially associates with pericentromeric chromatin and is required for deacetylation and H3K27me3 deposition established in the central cell. The epigenetic state established by maternal VEL3 is retained in mature seeds, and controls seed dormancy in part through repression of programmed cell death-associated gene ORE1. Our data demonstrates a novel mechanism by which maternal control of progeny seed physiology persists post-shedding, maintaining parental control of seed behaviour.
Project description:Seeds establish dormancy to delay germination until the arrival of a favorable growing season. In this study, we identify a fate switch comprised of the MKK3–MPK7 kinase cascade and the ethylene response factor ERF4 that is responsible for the seed state transition from dormancy to germination. We show that dormancy-breaking factors activate the MKK3–MPK7 module, which affects the expression of some α-EXPANSIN (EXPA) genes to control seed dormancy. Furthermore, we identify a direct downstream substrate of this module, ERF4, which suppresses the expression of these EXPAs by directly binding to the GCC boxes in their exon regions. The activated MKK3–MPK7 module phosphorylates ERF4, leading to its rapid degradation and thereby releasing its inhibitory effect on the expression of these EXPAs. Collectively, our work identifies a signaling chain consisting of protein phosphorylation, degradation, and gene transcription, by which the germination promoters within the embryo sense and are activated by germination signals from ambient conditions.
Project description:Production of morphologically and physiologically variable seeds is an important strategy that helps plants to survive in unpredictable natural conditions. However, the model plant Arabidopsis thaliana and most agronomically essential crops yield visually homogenous seeds. Using automated phenotype analysis, we observed that in Arabidopsis small seeds tend to have higher primary and secondary dormancy levels when compared to large ones. Transcriptomic analysis revealed distinct gene expression profiles between large and small seeds. Large seeds had higher expression of translation-related genes implicated in germination competence. In contrast, small seeds showed elevated expression of many positive regulators of dormancy, including a key regulator of this process – the DOG1 gene. Differences in DOG1 expression were associated with differential production of its alternative cleavage and polyadenylation isoforms where in small seeds proximal poly(A) site is selected resulting in a short mRNA isoform. Furthermore, single-seed RNA-seq analysis demonstrated that large seeds resemble DOG1 knockout mutant seeds. Finally, on the single seed level, the expression of genes affected by seed size was correlated with the expression of genes positioning seeds on the path towards germination. Our results demonstrate an unexpected link between seed size and dormancy phenotypes in a species producing highly homogenous seed pools, suggesting that the correlation between seed morphology and physiology is more widespread than initially assumed.
Project description:Seed dormancy is an adaptive trait whereby germination is blocked under favourable conditions to avoid germination out of season. Over time mature dry seeds lose dormancy and gradually acquire the capacity to germinate. Dormancy levels, i.e. the time required to release dormancy of the newly produced dry seed, are influenced by the environment of the mother plant and particularly by cold temperatures, which increase dormancy levels. It is also known that the seed coat, a maternal dead tissue, is important to keep seeds dormant over time, probably by shielding the seed living tissues from atmospheric oxygen. Biochemical and genetical evidence previously established that cold promotes polyester accumulation in the seed coat and mutant seeds deficient in polyester biosynthesis have low dormancy and viability. However, it is unclear which seed coat structures, such as apoplastic barriers, are remodeled or created de novo in response to cold during seed development. Combining histological and genetical approaches, a previously uncharacterized apoplastic barrier located in the outer integument 1 (oi1) cell layer was discovered. This barrier is strongly reinforced by cold and this process requires a MYB107 transcription factor , specifically expressed in oi1 cells. myb107 mutants is lacking the MYB107 TF, lacking the barrier and are less dormant, thus providing direct evidence that this barrier promotes dormancy in Arabidopsis.