̽��ֱ�� of Cambridge - Crop Science Centre

Scientists discover secret of virgin birth, and switch on the ability in female flies

jg533 — Fri, 28 Jul 2023 15:04:16 +0000

For the first time, scientists have managed to induce virgin birth in an animal that usually reproduces sexually: the fruit fly Drosophila melanogaster.

Once induced in this fruit fly, this ability is passed on through the generations: the offspring can reproduce either sexually if there are males around, or by virgin birth if there aren’t.

For most animals, reproduction is sexual - it involves a female’s egg being fertilised by a male’s sperm. Virgin birth, or ‘parthenogenesis’, is the process by which an egg develops into an embryo without fertilisation by sperm – a male is not needed.

̽��ֱ��offspring of a virgin birth are not exact clones of their mother but are genetically very similar, and are always female.

“We’re the first to show that you can engineer virgin births to happen in an animal – it was very exciting to see a virgin fly produce an embryo able to develop to adulthood, and then repeat the process,” said Dr Alexis Sperling, a researcher at the ̽��ֱ�� of Cambridge and first author of the paper.

She added: “In our genetically manipulated flies, the females waited to find a male for half their lives - about 40 days - but then gave up and proceeded to have a virgin birth.”

In the experiments, only 1-2% of the second generation of female flies with the ability for virgin birth produced offspring, and this occurred only when there were no male flies around. When males were available, the females mated and reproduced in the normal way.

Switching to a virgin birth can be a survival strategy: a one-off generation of virgin births can help to keep the species going.

̽��ֱ��study is published in the journal Current Biology.

To achieve their results, researchers first sequenced the genomes of two strains of another species of fruit fly, called Drosophila mercatorum. One strain needs males to reproduce, the other reproduces only through virgin birth. They identified the genes that were switched on, or switched off, when the flies were reproducing without fathers.

With the candidate genes for virgin birth ability identified in Drosophila mercatorum, the researchers altered what they thought were the corresponding genes in the model fruit fly, Drosophila melanogaster. It worked: Drosophila melanogaster suddenly acquired the ability for virgin birth.

̽��ֱ��research involved over 220,000 virgin fruit flies and took six years to complete.

Key to the discovery was the fact that this work was done in Drosophila melanogaster – the researchers say it would have been incredibly difficult in any other animal. This fly has been the ‘model organism’ for research in genetics for over 100 years and its genes are very well understood.

Sperling, who carried out this work in the Department of Genetics, has recently moved to Cambridge Crop Science Centre to work on crop pests and hopes to eventually investigate why virgin birth in insects may be becoming more common, particularly in pest species.

“If there’s continued selection pressure for virgin births in insect pests, which there seems to be, it will eventually lead to them reproducing only in this way. It could become a real problem for agriculture because females produce only females, so their ability to spread doubles,” said Sperling.

̽��ֱ��females of some egg-laying animals – including birds, lizards and snakes, can switch naturally to give birth without males. But virgin birth in animals that normally sexually reproduce is rare, often only observed in zoo animals, and usually happens when the female has been isolated for a long time and has little hope of finding a mate.

̽��ֱ��research was funded by the Leverhulme Trust.

Reference

Sperling, A L et al.: ‘A genetic basis for facultative parthenogenesis in Drosophila.’ Current Biology, July 2023. DOI: 10.1016/j.cub.2023.07.006

Scientists have pinpointed a genetic cause for virgin birth for the first time, and once switched on the ability is passed down through generations of females.

It was very exciting to see a virgin fly produce an embryo able to develop to adulthood

Alexis Sperling

Jose Casal and Peter Lawrence

Fruit fly, Drosophila mercatorum

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Crop Science Centre to conduct field trials of genetically modified barley that could reduce need for synthetic fertilisers

jg533 — Wed, 23 Mar 2022 10:49:52 +0000

A field trial of genetically modified and gene-edited barley is due to be planted this April. ̽��ֱ��research is evaluating whether improved crop interactions with naturally occurring soil fungi promote more sustainable food production.

Scientists are hopeful that the results from the trial will demonstrate ways to reduce the need for synthetic fertilisers, which could have significant benefits for improving soil health while contributing to more sustainable and equitable approaches to food production.

̽��ֱ��trial is being conducted by researchers at the Crop Science Centre, an alliance between the ̽��ֱ�� of Cambridge and the crop research organisation NIAB. It will evaluate whether improving crop interactions with naturally occurring soil fungi can help them more efficiently absorb water along with nitrogen and phosphorous from the soil. Nitrogen and phosphorous are two essential nutrients critical to crop production that are often provided through synthetic fertilisers.

While the use of synthetic fertilisers increases crop productivity, excessive applications in high and middle-income countries has caused environmental pollution that reduces biodiversity, as well as producing greenhouse gas emissions. Meanwhile, in low-income countries, fertilisers are often too expensive or unavailable to local farmers, which limits food production. That contributes to both hunger and poverty, because in regions like sub-Saharan Africa, most people depend on farming to support their families.

“Working with natural and beneficial microbial associations in plants has the potential to replace or greatly reduce the need for inorganic fertilisers, with significant benefits for improving soil health while contributing to more sustainable and equitable approaches to food production,” said Professor Giles Oldroyd, Russell R Geiger Professor of Crop Science, who is leading the work.

He added: “There is an urgent need for ecologically sound approaches to food production that can satisfy the demands of a growing global population while respecting limits on natural resources. We believe biotechnology can be a valuable tool for expanding the options available to farmers around the world.”

̽��ֱ��trial will evaluate a barley variety that has been genetically modified to boost expression levels of the NSP2 gene. This gene is naturally present in barley and boosting its expression enhances the crop’s existing capacity to engage with mycorrhizal fungi.

In addition, the trial will test varieties of barley that have been gene edited to suppress their interaction with arbuscular mycorrhizal fungi. This will allow scientists to better quantify how the microbes support plant development by assessing the full spectrum of interactions. They will measure yield and grain nutritional content in varieties with an enhanced capacity to engage the fungi and those in which it has been suppressed--while comparing both to the performance of a typical barley plant.

Professor Oldroyd said: “Barley has properties that make it an ideal crop for studying these interactions. ̽��ֱ��ultimate goal is to understand whether this same approach can be used to enhance the capacity of other food crops to interact with soil fungi in ways that boost productivity without the need for synthetic fertilisers."

̽��ֱ��trial will assess production under high and low phosphate conditions. It will also investigate additional potential benefits of the relationship with mycorrhizal fungi, such as protecting crops from pests and disease.

̽��ֱ��trial will follow the regulations that govern the planting of genetically modified crops in the UK, with oversight conducted by Defra and its Advisory Committee on Releases to the Environment (ACRE.) There will also be inspections during the trial, carried out by the Genetic Modification Inspectorate, which is part of the UK’s Animal and Plant Health Agency. ̽��ֱ��inspection reports will be publicly available.

More information about GM field trials

Trials will evaluate whether enhancing the natural capacity of crops to interact with common soil fungi can contribute to more sustainable, equitable food production.

Working with natural and beneficial microbial associations in plants has the potential to replace or greatly reduce the need for inorganic fertilisers

Giles Oldroyd

NIAB

Barley trial crop in field

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

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