Sacrifice for survival
NUS plant biologists have discovered that the Arabidopsis plant sacrifices parts of its roots to survive under cold weather conditions.
Plants adopt different strategies to adapt to their natural environment. In temperate regions, forest trees lose their leaves to conserve energy during the cold season. NUS researchers have found that when the weather gets colder, plants may selectively “kill off” parts of their roots. This is to enhance the survival of their stem cells and protect themselves from the cold. Plant stem cells produce signals that regulate the balance between self-renewal and the creation of daughter cells that develop into new tissues. This strategy allows plants to withstand low temperature-related stresses and to recover faster when the weather turns better.
Prof XU Jian and his research team from the Department of Biological Sciences, NUS found that chilling (low, but above-freezing) temperature leads to DNA damage in the Arabidopsis root stem cells and their early descendants. However, only the columella stem cell daughters (CSCDs) die preferentially. Inhibition of the DNA damage response in CSCDs prevents their death but this increases the probability that the stem cells will die due to the cold. In collaboration with Prof MIRONOVA from the Novosibirsk State University, they discovered that the CSCD death allows maintenance of a functional stem cell niche under chilling stress. This sacrificial mechanism improves the root’s ability to withstand accompanying environmental stresses and to recover faster when optimal temperatures are restored.
Understanding the biological significance of selective cell death in response to different DNA damage-inducing stresses has been a challenge to biologists for many years. Temperature stress, which induces DNA damage in plant cells, has a profound effect on plant development. However, its effects on plant stem cell behaviour and activity is still not well understood. This research attempts to address these existing gaps by using the plant root stem cell niche as an experimental model to perform in-depth studies at high spatial and temporal resolutions. It provides a better understanding of the survival strategies plants employ when the odds are stacked against them.
Plant roots have been largely neglected by agricultural researchers in crop improvement. Their importance and potential in raising crop productivity have only been recognised recently. Chilling stress from cold weather conditions cause injuries to crops, reducing the amount of harvest which we can get from them. Prof Xu commented, “By developing a deeper understanding for the effects of chilling temperatures on a plant, and how plants naturally adapt to chilling stress, it may be possible to engineer cold tolerance in plants so that they can withstand harsh environmental conditions. This will allow farmers to extend the growing season of crops and the land area in which to grow them, increasing both yield stability and production capacity.”
Figure shows the selective death of CSCDs prevent the death of root stem cells during chilling stress. Dead cells are colour-coded in red. [Image credit: Ajay DEVENDRAN]
Hong JH; Savina M; Du J; Devendran A; Kannivadi Ramakanth K; Tian X; Sim WS; Mironova VV; Xu J*, “A sacrifice-for-survival mechanism protect root stem cell niche from chilling stress”, CELL DOI: 10.1016/j.cell.2017.06.002 Published: 2017.