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: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:The role of on-CG methylation in seed development and dormancy remains unknown. There are four genes in charge of non-CG methylation in Arabidopsis: drm1, drm2, cmt2 and cmt3. The majority of non-CG methylation in vegetative tissues, leaf, is gone in homozygous ddcc mutant line (Hume et al., 2014). To uncover the possible role of non-CG DNA methylation in seed development and dormancy, we characterized the methylome of ddcc mutant in Arabidopsis dry seed using Illumina sequencing. Meanwhile, vegetative tissue, leaves from 3 week plant with ddcc mutant and from wild type, and dry seed from wild type plant were used as control. Illumina sequencing of bisulfite-converted genomic DNA from dry seed and 3-week-plant leaves of ddcc mutant and wild type.
Project description:There are four major seed developmental phases in Arabidopsis seed development: morphogenesis, maturation, dormancy and germination. What methylation changes occurring in the different phases, if any, remains unknown. To uncover the possible role of DNA methylation in different parts of the seed, we characterized the methylome of four major seed developmental phases of Arabidopsis using Illumina sequencing: global stage (glob) and linear cotyledon stage (lcot) for morphogenesis phase; mature green stage (mg) and post mature green stage (pmg) for maturation phase; dry seed (dry) for dormancy phase; leaves (leaf) from 4 week plant for vegetative tissues. Illumina sequencing of bisulfite-converted genomic DNA from six seed developmental stages in Arabidopsis: global stage (glob), linear cotyledon stage (lcot), mature green stage (mg), post mature green stage (pmg), dry seed (dry) and leaves (leaf) from 4 week plant.
Project description:The role of non-CG methylation in seed development and dormancy remains unknown. There are four genes in charge of non-CG methylation in Arabidopsis: drm1, drm2, cmt2 and cmt3. The majority of non-CG methylation in vegetative tissues, leaf, is gone in homozygous ddcc mutant line (Hume et al., 2014). To uncover the possible role of non-CG DNA methylation in seed development and dormancy, we characterized the methylome of ddcc mutant in Arabidopsis postmature-green-stage seed and dry seed using Illumina sequencing. Meanwhile, vegetative tissue, leaves from 3 week plant with ddcc mutant and from wild-type, and postmature-green-stage seed and dry seed from wild-type plant were used as control.
Project description:There are four major seed developmental phases in Arabidopsis seed development: morphogenesis, maturation, dormancy and germination. What methylation changes occurring in the different phases, if any, remains unknown. To uncover the possible role of DNA methylation in different parts of the seed, we characterized the methylome of four major seed developmental phases of Arabidopsis using Illumina sequencing: global stage (glob) and linear cotyledon stage (lcot) for morphogenesis phase; mature green stage (mg) and post mature green stage (pmg) for maturation phase; dry seed (dry) for dormancy phase; leaves (leaf) from 4 week plant for vegetative tissues.
Project description:The role of on-CG methylation in seed development and dormancy remains unknown. There are four genes in charge of non-CG methylation in Arabidopsis: drm1, drm2, cmt2 and cmt3. The majority of non-CG methylation in vegetative tissues, leaf, is gone in homozygous ddcc mutant line (Hume et al., 2014). To uncover the possible role of non-CG DNA methylation in seed development and dormancy, we characterized the transcriptome of ddcc mutant in Arabidopsis post-mature green seeds using Illumina sequencing. Meanwhile, post-mature green seeds from wild type were used as control.
Project description:Freshly harvested Arabidopsis seeds (ecotype Col0 obtained under 10 mM nitrate nutrition, referred to as C10 seeds) are dormant and do not germinate when sown on an agarose-based medium. However, when C10 seeds are sown on 10mM nitrate or when Col0 mother plants are grown on 50 mM nitrate (referred to as C50 seeds), the produced seeds are non dormant and germinate readily on agarose. The G4-3 arabidopsis mutant which is impaired in nitrate assimilation and accumulates nitrate produces likewise non dormant seeds when grown on 10mM nitrate (referred to as G4-3 seeds). The goals of these experiments are to better understand the effects of nitrate feeding of mother plants on the produced seed dormancy.
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:sRNA-seq profiling of 10 time points during germination in Arabidopsis, from freshly harvested seed, through mature seed, stratification, germination and to post-germination.