The ARGOS-LIKE genes of Arabidopsis and tobacco as targets for improving plant productivity and stress tolerance

A small family of ARGOS genes encodes transmembrane proteins that act as negative regulators of ethylene signaling. Recent studies show that ARGOS genes are involved in the regulation of plant growth under the influence of stress factors. However, the role of ARGOS genes in this process is poorly known. Thereby, our goal was to determine the expression profile of these genes in Arabidopsis thaliana and Nicotiana tabacum in response to phytohormone treatment and stress factors. We discovered that expression of the AtARGOS and AtARGOS-LIKE genes of A. thaliana is regulated by ethylene and depends on environmental conditions. The highest expression level of the NtARGOS-LIKE1 gene of tobacco (NtARL1) was observed in blooming flowers and young organs. It was induced by auxins, ethylene, ABA, methyl jasmonate as well as hypothermia, drought, salinity and heat stresses. To evaluate the impact of ARGOS genes on plant growth under stress, we created transgenic tobacco plants with constitutive expression of the AtARGOS-LIKE gene of A. thaliana (AtARL), controlled by a strong Dahlia mosaic virus promoter. Overexpression of the AtARL gene contributed to an increase in the volume and quantity of mesophyll cells in the leaves of tobacco under normal conditions, and also to an improvement in root growth under salinity, cold and cadmium treatment. The AtARL transgene produced a positive effect on shoot growth when exposed to drought and high salinity, and a negative effect under cold stress. Accordingly, genes of the ARGOS family can be recommended as targets for genetic engineering and genome editing in order to enhance productivity and stress tolerance of economically important plants.