Understanding the effects of salt on plants
It has been known for some time that plants protect themselves from soils with high levels of salinity by rerouting their roots to avoid local high salt concentrations. In a recent review and video abstract published in the journal Trends in Plant Science, UvA researchers Christa Testerink and Magdalena Julkowska summarise the current body of knowledge on the effects of salt stress on plants on various time scales and in various organs.
Plants are flexible organisms. They have the potential to adjust their shape depending on the conditions to which they are exposed. This has helped plants to colonise almost every corner of the globe. But just like humans, plants and crops cannot survive on salt water. Rising sea levels and irrigation cause an increase in the salinisation of soils, making high salinity one of the major abiotic factors threatening food security across the globe. Exposure to salt stress activates many signaling pathways, which in tolerant plants leads to acclimation.
The immediate effects of salt stress
In their review, the authors integrate the state of knowledge on those early signaling responses, taking place seconds to minutes, with the growth of different organs occurring hours to days. According to the authors, plants exposed to salt stress cease to grow immediately. At this stage, salt enters the cells through non-specific ion channels in the membrane, which then triggers a series of events within the cells that lead to production of stress hormones and a reduction in cell division and cell growth. Although growth slightly recovers at a later stage as salt ions are pumped into vacuoles and storage tissues, it hardly every reaches control levels.
An interesting phenomenon, the authors point out, is that the growth of individual plant organs is affected to different degrees by salt stress. When salt stress plants are compared to normal grown plants, they show a different architecture. A number of recent studies on this subject suggest that relative changes in growth morphology are indeed important contributors to salt tolerance. As such, the authors believe these changes provide new leads for breeding salt tolerant crops. Testerink: We want to understand how changes in root architecture can reduce salt absorption, so we can improve salt stress tolerance and, in the end, crop yield.'
Breeding new crops
Testerink, a plant physiologist at the UvA’s Swammerdam Institute for Life Sciences (SILS), was recently awarded a prestigious NWO grant from the Netherlands Organisation for Scientific Research. With this grant, Testerink and her team will continue their research into the effects of salt stress on root formation and search for possible ways to breed crops that are better able to resist higher levels of soil salinisation.
Magdalena M. Julkowska, Christa Testerink. Tuning plant signaling and growth to survive salt. Trends in Plant Science (Volume 20, Issue 9, p586–594, September 2015).