This finding – obtained using next generation sequencing technology – was reported by an international team of researchers including plant geneticists from the University of Zurich. This newly uncovered mechanism may be involved in the maintenance of species boundaries and could play an important role in the development of novel crop varieties.
Mother and father each contribute one half of the genetic information to their offspring. Thus, it was thought that both parents contribute equally to the development of the next generation. Indeed, this holds true for late stages of embryo development in plants, but early on, things are quite different: during the earliest phase of embryo development - from the fertilized egg to the globular stage - predominantly the maternal genes are active. This phase of development is controlled largely by maternal factors, which actively repress or silence the genes inherited from the father. This surprising finding was recently published in the renowned American journal CELL, by an international team of scientists led by plant geneticists from the Universities of Zurich and Montpellier.
Silenced Paternal Genes
For their analysis, the Zürich scientists crossed two genetically distinguishable races of the model plant Arabidopsis thaliana (tale cress) and analyzed the relative contributions of the parental genomes shortly after the first division of the fertilized egg. Such molecular genetic analyses of plant embryos at very early stages are technically challenging, which explains why up to now researchers resorted to studying embryos at later stages. But Ueli Grossniklaus, Professor for Plant Developmental Genetics at University of Zurich, has a marked preference for tackling experimentally challenging problems, including the study of gametes and very young embryos that are hard to obtain.
Using "Next Generation Sequencing", a novel and powerful technology, Grossniklaus and colleagues were able to show that in an early phase of plant embryo development, predominantly maternal genes are active. Via small ribonucleic acid molecules (siRNAs), the maternal genome controls paternal genes to ensure that, initially, most remain inactive.
In the course of development, paternal genes are sucessively activated, which also requires the activity of maternal factors. This finding is surprising because it contradicts earlier findings, which suggested that these siRNAs have a specifc role in preventing "jumping genes" (transposons) to move within the genome.
According to Grossniklaus, the transient silencing of the paternal contribution during early development of the offspring is in the mother plant’s best interest: the mother invests considerable resources into the formation of seeds. Before making this investment, the mother verifies the paternal contribution to the progeny for compatibility with her own genome. If the father’s genome is too divergent from her own, e.g., originating from a different species, the embryo will die.
In fact, the two parental plants have opposing interests with regard to their offspring. The pollen-donating father is interested in maximizing transfer of resources from the mother to the offspring. By contrast, the mother plant aims at optimizing the match with the fathers genome in order to prevent a waste of resources. „We are dealing with a classical parental conflict“, Ueli Grossniklaus summarizes the opposing interests.
Maternal Control May Ensure the Maintenance of Species Boundaries
Maternally active genes direct and control early embryogenesis. Genetic incompatibility will cause embryos to abort, such that fertilization with pollen from other plant species is not successful. Therefore, the mechanism unraveled by Grossniklaus and colleagues may play an important role in the maintenance of species barriers. This may also explain why attempts to cross crop plants with their wild relatives, e.g., to transfer disease-resistance genes present in wild relatives to crops, often fail early in embryogenesis. A genetic divergence between the parents that is too large may be recognized by this novel mechanism, leading to embryo abortion. Commercial crop breeders will thus be interested in finding out how the maternal control of early plant embryo development can be circumvented in their breeding programs.Reference:
Beat Müller | idw
Cryo-electron microscopy achieves unprecedented resolution using new computational methods
24.03.2017 | DOE/Lawrence Berkeley National Laboratory
How cheetahs stay fit and healthy
24.03.2017 | Forschungsverbund Berlin e.V.
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
24.03.2017 | Materials Sciences
24.03.2017 | Physics and Astronomy
24.03.2017 | Physics and Astronomy