Researchers from the Institute of Molecular and Cellular Biology of Plants publish the most precise description of the changes that determine the stoppage of flower and fruit production in plants with a single reproductive episode
Although it sounds strange, some plants undergo a kind of ‘menopause’. Known as proliferative arrest, it affects annual plants that only flower once – known as monocarpic plants – and then die. The first part, that of flowering, is a well-studied process: the influence of light, seasonal changes, temperature, or the age of the plant at which the flowers appear has been analyzed in depth. However, there is a gap in the investigation of what his end is like. Now, a group of researchers from the Plant Molecular and Cellular Biology Institute (IBMCP), a joint center of the Higher Council for Scientific Research (CSIC) and the Polytechnic University of Valencia (UPV), publishes in the journal ‘ Current Biology’ the most complete analysis of this process which, if it could be controlled, would be an opportunity to, for example, lengthen the reproductive phase of crops as important as legumes or cereals.
Although they only flower once, monocarpic plants can live for years. In fact, flowering does not in itself result in the death of the plant, although it is true that the production of fruits and seeds causes changes that will lead to its death. These changes are induced by hormones that divert resources from roots and leaves toward the production of fruits and seeds.
Cristina Ferrándiz Maestre, a researcher at the IBMCP and one of the authors of the study, explains in a statement that “this process that we could call the vegetal menopause constitutes a great evolutionary adaptation since, by not forming new organs such as flowers and fruits, the redistribution of nutrients towards the production of seeds, allowing their optimal development and thus perpetuating the species”, explains Ferrándiz.
However, despite its ecological and economic importance, little is known about the factors that control the arrest of proliferation. Using molecular and cellular biology, genetics, and image analysis techniques to the model species Arabidopsis thaliana -a herbaceous plant, the first from which its complete genome was obtained- to define with high Spatio-temporal resolution the sequence of molecular and cellular events that trigger the arrest of proliferation.
How to control vegetable menopause
The investigation has two aspects. On the one hand, the changes that occur in the meristem -tissues responsible for plant growth- before the proliferative arrest have been analyzed: how and when cells stop dividing, at what moment signs of aging begin to be seen when the activity of stem cells… “It’s like zooming in on the meristem to understand which phases take place and what characterizes them”, says Paz Merelo, IBMCP researcher who leads the study.
“On the other hand, we have studied some important plant hormones to maintain proliferation, the cytokinins. With fluorescent markers that allow us to follow its activity, we have seen that its activity is completely blocked at the moment of the stop, so, probably, the cytokinins are the triggers of the stop -reveals Merelo-. In addition, we have verified that, if we treat the meristems with cytokinins externally, they do not stop producing stem cells”.
Longer lasting harvests
According to its authors, the study is pioneering because, for the first time, it has been closely observed how these tissues responsible for growth change around plant ‘menopause’. “This will allow us to design new experiments to control the flowering period and its end, or to identify more factors involved in its control,” says Ferrándiz. Proliferation arrest is a common process in a wide range of species, so the described processes are relevant for new biotechnological approaches aimed at increasing crop yields by extending the duration of the flowering period, or delaying proliferation arrest. .
“As this study demonstrates that cytokinins prevent proliferation from stopping and, therefore, extend the production period, the pathways related to these hormones would be promising targets in breeding programs -says Ferrándiz-. In addition, the yield of many crops depends to a large extent on environmental conditions, so obtaining plant varieties with a longer reproductive phase, or with a late proliferation stop, would allow production to be adjusted to specific climatic changes.
