Unveiled the great secret of flowers: discover how their stigmas are formed


Field of flowers.

Field of flowers.
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The stigma it is the entrance door of pollen to plants with flowers. This tissue is located at the end of the pistils and acts trapping pollen, allowing pollination and fertilization of seeds and reproduction.

The genes involved in the formation of this organ, but not the mechanism by which they interact.

Now, a research group from the Institute of Molecular and Cellular Plant Biology (IBMCP), joint center of the Higher Council for Scientific Research (CSIC) and the Polytechnic University of Valencia (UPV), publishes in The Plant Cell the puzzle that deciphers the relationship of these genes to allow the formation of stigma in flowering plants, an innovation that endowed them with a evolutionary advantage in front of others.

Stigma is vital to reproductive success

The stigma is a specialized tissue, characteristic of the angiosperms (flowering plants), which forms on top of the pistil, the female organ of the flower. It is essential for trapping and germinating pollen grains, and it also acts as a barrier to ensure that only the correct pollen species enter the pistil to fertilize the eggs.

The correct development of stigma is key to reproductive success of flowering plants and fruit and seed production in crop plants, so it is important to understand the genetics behind this process.

“They have carried out genetic and molecular analyzes to propose a model that explains how various genes interact cooperatively to promote the development of stigma”

Using the plant model Arabidopsis thaliana, the IBMCP research group has conducted extensive genetic analysis and molecular to propose a model that explains how various genes interact cooperatively to promote the development of stigma.

Until now, it was not clear how these genes, which encode transcription factors with diverse roles in other processes, they organize the ‘chain of command’ to specifically form the stigma and not other tissues, at the correct time and spatial domain of development.

“Thanks to this discovery, more extensive or functional stigmas could be developed for a longer time, with a greater capacity to trap pollen, and thus try to alleviate the shortage of natural pollinators”

Cristina Ferrándiz – IBMCP

“We have put together the puzzle of how genes known to be involved in the formation of stigma in Arabidopsis thaliana“, Explain Cristina Ferrándiz Maestre, researcher at the IBMCP and responsible for the work.

“All these transcription factors form a complex when they coincide at a given time and spatial domain, which gives instructions to form this tissue. A few other examples are known in flowering plants in which combinatorial variations in the composition of transcriptional complexes give rise to the development of specific tissues or organs ”, the researcher assures.

Possible applications

“Our goal now is to elucidate whether similar complexes drive the stigma formation in other speciesand if this evolutionary novelty could be related to other factors that gained the ability to combine to produce this new tissue, characteristic and specific of flowering plants ”, continues Ferrándiz.

“In addition, we want to know if different combinations of these and other factors they could direct the formation of other tissues of the pistil such as the style or the ovary ”, remarks the CSIC researcher.

For Ferrándiz, understanding this stigma formation mechanism opens the door to better understand the fertilization process of flowering plants, being able to favor the same.

“More extensive or functional stigmas could develop for a longer time, with a greater capacity to trap pollen, and thus try to alleviate the shortage of natural pollinators like the bees that are observed today ”, he points out.

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