New layer

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New layer

You would think that for one of the most studied plants in the world it is clear by now how it looks. Still Dutch researchers have found something new. In a bioRxiv preprint they show that the early embryo is surrounded by a thin shell, the embryo envelop. And to be fair, this shell is difficult to see.

All life has a separation barrier between itself and the outside world. To prevent entering of unwanted pathogens or substances. Therefore, most plants are covered with a wax-like layer. This layer is already seen early in the development, from the hart-shaped embryo onwards. But what about earlier during embryo development, asked the Dutch researchers, is there something that protects it from the outside world?

To investigate this the researchers studied young embryos under the electron microscope. They noticed a thin layer encapsulating the embryos completely. By measuring its thickness, the researchers could exclude the possibility that it was a cell wall or cell membrane. Qua thickness it fitted just between these two.

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The function of this new embryo envelop is still unclear

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But what did they find? As embryos of plants that don’t have a wax-like layer are still encapsulated by this thin layer, it suggested that the researchers found something completely novel.

To find out what the composition of this new shell, the researchers treated embryos with different dyes and antibodies. They noticed the shell lights up when using a fluorescent dye that binds to lipids. In addition, the researchers observed the binding of antibodies that bind O-glycoproteins.

The function of this new protein rich embryo envelop is still unclear. More research is needed to discover this. It can be that the embryo envelop protects the young embryo against influences from outside. It can have a mechanical function, whereby it gives the growing embryo structural support. Or it can be something the researchers have not thought about. That makes finding something new so exciting.

Literature

Yosapol Harnvanichvech, Cecilia Borassi, Diaa Eldin S. Daghma, Hanne M. van der Kooij, Joris Sprakel, Dolf Weijers (2023) An elastic proteinaceous envelope encapsulates the early Arabidopsis embryo. bioRxiv 2023.05.03.539186; doi: https://doi.org/10.1101/2023.05.03.539186