Breakthrough study reveals new insight into “immortal” plant cells

Posted by ew205 at Dec 18, 2017 05:07 PM |
DNA methylation discovery by team including University of Leicester

A new study has revealed an undiscovered reprogramming mechanism that allows plants to maintain fitness down the generations.

The John Innes Centre team led by Dr Xiaoqi Feng made the discovery when studying germ cells - cells specialised for sexual reproduction - in flowering plants.

Germ cells are often referred to as “immortal” because they can pass their genetic material through the generations, and they have been the subject of much scientific scrutiny.

This study aimed to solve a long-term debate on whether the germ cells in plants undergo an event of DNA methylation reprogramming at each reproductive cycle.

DNA methylation is a modification of DNA, which changes the activity of DNA without changing the genetic sequence.

It is a cornerstone of epigenetics – one of the fastest growing fields in life sciences with potential to deliver improvements in human and plant health.

DNA methylation reprogramming - known to exist in animals – occurs most dramatically in germ cells and regulates the reproductive success from generation to generation.

Published today in Nature Genetics, the team led by Dr Xiaoqi Feng from the John Innes Centre in collaboration with Dr James Higgins from the University of Leicester reveal for the first time the existence of DNA methylation changes in the germline of flowering plants.

They also reveal the mechanism by which this reprogramming happens - via a process known as de novo (anew) DNA methylation and its biological significance in maintaining reproductive success.

Dr Feng, project leader at the John Innes Centre, explains: “We knew this DNA methylation re-setting is extensive and important in animals where methylation is erased and re-established between generations.

“But because plants carry DNA methylation information really well through generations, it was believed there was not much methylation reprogramming going on in plant germ cells. What we have discovered shows plant germ cells also go through methylation reprogramming and functionally it is essential.”

Dr Higgins added “Disrupting the de novo methylation pathway also led to mis-splicing of a gene required during meiosis (a reproductive cell division) to aid the attachment of chromosomes to the cytoskeleton, thus forming daughter cells with double the number of chromosomes.

“Therefore it is clear that epigenetic reprogramming is required to re-set methylation of the immortal germ cells as well as regulating aspects of gene regulation during reproduction in the flowering plant Arabidopsis”.

The full paper: Sexual-lineage-specific DNA methylation regulates Arabidopsis meiosis is available published in Nature Genetics at https://doi.org/10.1038/s41588-017-0008-5

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