Effects of nitrogen deficiency and drought stresses on miRNA expressions in Arabidopsis thaliana

Abstract

MicroRNAs are now known to have an important role in regulating gene expression of eukaryotic organisms. miRNA research in plants gained importance after the discovery that several stress factors alter certain miRNA expressions, which subsequently regulate their target gene expressions and affect development and growth of plants. In this study, two of the widely studied abiotic stress conditions for plants, nitrogen deficiency and drought were used individually and as a combined stress treatment on Arabidopsis thaliana callus tissues to observe the change of expressions in certain miRNAs, when multiple stressors are encountered. Combined stress strongly inhibited callus growth compared to other conditions, while strongly altering certain miRNA expressions. Compared to control, in 7-day stress treated callus, miR165a-3p,b, miR319a,b, miR396b-5p, miR399d and miR827 showed significant downregulation for all stress treatments, while 7-day N deficiency caused miR167 upregulation. Stress treatments for 7 days mostly downregulated miR167c-5p, miR319c, miR399a, miR399e expressions except for the N deficient samples. After 14 days of stress, miR165a-3p,b, miR396a-5p, miR399b, miR399d were downregulated. During 14-day drought and combined stress, miR399a and miR396b-5p expressions were upregulated, respectively. The differences observed in this study between stress responses of 7 and 14-day-long treatments are believed to be valuable to further elucidate the associated molecular mechanisms of miRNAs, determination and validation of miRNA targets, and how plants respond to stress conditions via various genetic regulations.