Gene that confers seed tolerance to salinity identified

Seeds only germinate when a series of internal and environmental needs are met. Otherwise, they get stuck in a state of dormancy. Researchers from the Instituto Gulbenkian de Ciência (IGC) led by Paula Duque just revealed a mechanism that allows plants to integrate environmental signals and decide whether they should initiate development. SCL30a is a gene behind this decision system.

The group’s interest in this gene came from gene expression studies in Arabidopsis thaliana, a model plant belonging to the cabbage and turnip family. The increased expression of SCL30a during germination made them suspect that it could define morphological and functional characteristics of seeds in response to stress.

To address this hypothesis, the researchers altered the expression of the SCL30a protein and assessed the seeds’ characteristics in a variety of settings. When they treated seeds lacking this protein with salt, these germinated less and later than normal seeds. By contrast, seeds overexpressing the protein germinated twice as fast, especially under adverse conditions.

The analyses the researchers carried out revealed that these outcomes stemmed from the inhibition of signals sent by abscisic acid (ABA), a hormone that restrains germination in stress conditions. By controlling the expression of genes induced by this hormone, the SCL30a protein reduces the plant’s sensitivity to high salinity, allowing seeds to germinate. “These findings are in line with accumulating evidence showing that regulation of gene expression by this class of proteins is crucial to control plant stress responses”, Tom Laloum, a postdoctoral researcher at the IGC and one of the first authors of the study, explains. The researchers also showed that this protein controls other aspects of plant development mediated by ABA, including seed size, which increased when SCL30a was overexpressed. 

The principal investigator Paula Duque explains that these genetic functions “could be translated into crop species, resulting in larger seeds that germinate better under adverse environments”. This could solve limitations on crop productivity due to soil salinization, a problem that is expanding in different areas of the world, including Portugal.