| 1. |
- Kradolfer, David, et al.
(författare)
-
An Imprinted Gene Underlies Postzygotic Reproductive Isolation in Arabidopsis thaliana
- 2013
-
Ingår i: Developmental Cell. - : Elsevier BV. - 1534-5807 .- 1878-1551. ; 26, s. 525-535
-
Tidskriftsartikel (refereegranskat)abstract
- Postzygotic reproductive isolation in response to interploidy hybridizations is a well-known phenomenon in plants that forms a major path for sympatric speciation. A main determinant for the failure of interploidy hybridizations is the endosperm, a nutritious tissue supporting embryo growth, similar to the functional role of the placenta in mammals. Although it has been suggested that deregulated imprinted genes underpin dosage sensitivity of the endosperm, the molecular basis for this phenomenon remained unknown. In a genetic screen for suppressors of trip-bid seed abortion, we have identified the paternally expressed imprinted gene ADMETOS (ADM). Here, we present evidence that increased dosage of ADM causes triploid seed arrest. A large body of theoretical work predicted that deregulated imprinted genes establish the barrier to interploidy hybridization. Our study thus provides evidence strongly supporting this hypothesis and generates the molecular basis for our understanding of postzygotic hybridization barriers in plants.
|
|
| 2. |
- Kradolfer, David, et al.
(författare)
-
Endosperm cellularization defines an important developmental transition for embryo development
- 2012
-
Ingår i: Development. - : The Company of Biologists. - 0950-1991 .- 1477-9129. ; 139, s. 2031-2039
-
Tidskriftsartikel (refereegranskat)abstract
- The endosperm is a terminal seed tissue that is destined to support embryo development. In most angiosperms, the endosperm develops initially as a syncytium to facilitate rapid seed growth. The transition from the syncytial to the cellularized state occurs at a defined time point during seed development. Manipulating the timing of endosperm cellularization through interploidy crosses negatively impacts on embryo growth, suggesting that endosperm cellularization is a critical step during seed development. In this study, we show that failure of endosperm cellularization in fertilization independent seed 2 (fis2) and endosperm defective 1 (ede1) Arabidopsis mutants correlates with impaired embryo development. Restoration of endosperm cellularization in fis2 seeds by reducing expression of the MADS-box gene AGAMOUS-LIKE 62 (AGL62) promotes embryo development, strongly supporting an essential role of endosperm cellularization for viable seed formation. Endosperm cellularization failure in fis2 seeds correlates with increased hexose levels, suggesting that arrest of embryo development is a consequence of failed nutrient translocation to the developing embryo. Finally, we demonstrate that AGL62 is a direct target gene of FIS Polycomb group repressive complex 2 (PRC2), establishing the molecular basis for FIS PRC2-mediated endosperm cellularization.
|
|
| 3. |
- Kradolfer, David, et al.
(författare)
-
Increased Maternal Genome Dosage Bypasses the Requirement of the FIS Polycomb Repressive Complex 2 in Arabidopsis Seed Development
- 2013
-
Ingår i: PLoS Genetics. - : Public Library of Science (PLoS). - 1553-7390 .- 1553-7404. ; 9
-
Tidskriftsartikel (refereegranskat)abstract
- Seed development in flowering plants is initiated after a double fertilization event with two sperm cells fertilizing two female gametes, the egg cell and the central cell, leading to the formation of embryo and endosperm, respectively. In most species the endosperm is a polyploid tissue inheriting two maternal genomes and one paternal genome. As a consequence of this particular genomic configuration the endosperm is a dosage sensitive tissue, and changes in the ratio of maternal to paternal contributions strongly impact on endosperm development. The FERTILIZATION INDEPENDENT SEED (FIS) Polycomb Repressive Complex 2 (PRC2) is essential for endosperm development; however, the underlying forces that led to the evolution of the FIS-PRC2 remained unknown. Here, we show that the functional requirement of the FIS-PRC2 can be bypassed by increasing the ratio of maternal to paternal genomes in the endosperm, suggesting that the main functional requirement of the FIS-PRC2 is to balance parental genome contributions and to reduce genetic conflict. We furthermore reveal that the AGAMOUS LIKE (AGL) gene AGL62 acts as a dosage-sensitive seed size regulator and that reduced expression of AGL62 might be responsible for reduced size of seeds with increased maternal genome dosage.
|
|
| 4. |
- Yi, Jun, et al.
(författare)
-
Meiocyte size is a determining factor for unreduced gamete formation in Arabidopsis thaliana
- 2023
-
Ingår i: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 237, s. 1179-1187
-
Tidskriftsartikel (refereegranskat)abstract
- Polyploidy, the presence of more than two sets of chromosomes within a cell, is a widespread phenomenon in plants. The main route to polyploidy is considered through the production of unreduced gametes that are formed as a consequence of meiotic defects. Nevertheless, for reasons poorly understood, the frequency of unreduced gamete formation differs substantially among different plant species. The previously identified meiotic mutant jason (jas) in Arabidopsis thaliana forms about 60% diploid (2n) pollen. JAS is required to maintain an organelle band as a physical barrier between the two meiotic spindles, preventing previously separated chromosome groups from uniting into a single cell.In this study, we characterized the jas suppressor mutant telamon (tel) that restored the production of haploid pollen in the jas background.The tel mutant did not restore the organelle band, but enlarged the size of male jas tel meiocytes, suggesting that enlarged meiocytes can bypass the requirement of the organelle band. Consistently, enlarged meiocytes generated by a tetraploid jas mutant formed reduced gametes.The results reveal that meiocyte size impacts chromosome segregation in meiosis II, suggesting an alternative way to maintain the ploidy stability in meiosis during evolution.
|
|
