This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: The majority of plant seeds have the special ability to almost completely dry out and yet remain viable. While most living cells die with a 90% loss of water, cells in seeds enter a biological state of dormancy.
With a moisture content of less than 10%—similar to a raisin compared to a grape—they become small time capsules and can lie dormant for decades until they are awakened by favorable environmental conditions. Then they must not miss the right time to germinate. For this, the "powerhouses of cells" necessary for energy supply—the mitochondria—must resume their work as quickly as possible.
How this is achieved is not yet known in detail. A new study, led by a research team from the Universities of Münster, Hanover and Halle (Germany), has now shown, using the example of thale cress (Arabidopsis thaliana), that the mitochondria are "on standby" in dry plant seeds. Their complex internal structure, with an outer and an inner membrane as well as numerous infoldings of the inner membrane, is already fully developed and not just present in an incomplete preliminary stage, as previous studies had suggested.
The research is published in the journal Current Biology. The structural and functional maturity of the mitochondria is the basis for their ability to function quickly—within a few minutes—and start so-called cellular respiration. In doing so, the seedling uses part of its reserves of carbohydrates, proteins and fats to generate the energy needed for growth.
As the study shows, seed mitochondria already contain the complete inventory of proteins that the seedling needs for cellular respiration. This allows the plant embryo to supply itself with energy from the very first moment of germination. The consortium of plant-mitochondria experts also examined the onset of cellular respiration in additional plant species, including rapeseed, millet and tomato.
The observations suggest that the rapid activation of mature mitochondria, triggered by the seed's first uptake of water, is widespread in flowering plants with dry ("orthodox") seeds. This property has clearly proven valuable and is evolutionarily conserved. "We have identified various proteins that contribute to the mitochondria surviving the dry phase until germination unharmed," said Professor Iris Finkemeier from the Institute of Plant Biology and Biotechnology at the University of Münster.
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