You might connect soil salinization with rising sea-levels, but it can be a problem inland too. It leads to an increase of metal ions and and turn the of soil more alkaline. Alkalinity is a challenge for many plants, leading to reduced growth and possibly even death. Qi Chen and colleagues have studied two grasses that grow well in alkaline soils to learn how they cope. They find the grasses, Suaeda salsa and Puccinellia tenuiflora have two different approaches to the same problem.
Chen and colleagues open their study with the staggering fact that “more than 20% of irrigated soils are affected by saline-alkali stress worldwide”. One area under threat is the Hulunbuir grassland in the north of Inner Mongolia. Human activity, including agriculture, has increased the soil pH of land making it more alkaline. Chen and colleagues collected samples of two grasses that can thrive in these conditions, Suaeda salsa and Puccinellia tenuiflora, to see how their metabolism changes to cope with this stress.
The team used gas chromatography–mass spectrometry to study the metabolites in the grasses. The metabolites fell into two distinct clusters, indicating that the plants were producing two different sets of metabolites, rather than independently coming to the same solution. A key difference was that S. salsa relied on aboveground organs to tackle the toxins, while P. tenuiflora concentrated its efforts at the roots.
P. tenuiflora produced sugars to help protect from salt damage. The sugars give the plant the ability to regulate osmotic pressure. This allows the plant to better conserve water in its cells. S. salsa uses alcohols to control osmosis. The authors also add that alcohols work as natural scavengers of salinity-induced reactive oxygen species. Both plants used acids as well to tackle stress. Acids in the plant help counteract the alkaline material that they take up from the soil.
Understanding how grass can thrive in alkaline soils will help preserve pasture, but also has consequences for conservation. When plants start to die to the environment their loss can have negative consequences for the plants that remain. Getting grasses that can survive and transform an environment can help improve a habitat for other plants.
Chen Q, Xie H, Wei G, Guo X, Zhang J, Lu X, and Tang Z. 2022. “Metabolic Differences of Two Constructive Species in Saline-Alkali Grassland in China.” BMC Plant Biology. https://doi.org/10.1186/s12870-021-03401-y