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
Individual Receptors Caught at Work
19.10.2017 | Julius-Maximilians-Universität Würzburg
Rapid environmental change makes species more vulnerable to extinction
19.10.2017 | Universität Zürich
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
19.10.2017 | Materials Sciences
19.10.2017 | Materials Sciences
19.10.2017 | Physics and Astronomy