The role of the BHLH038 transcription factor in the regulation of osmotic and drought stress responses in Arabidopsis thaliana

The most important abiotic stress affecting agriculture worldwide is drought. In order to ensure food supply for the expanding world population two critical tasks must be undertaken; maintenance of crop yield as well as the increase of yield potential. Plants have built up a complex stress response system in order to survive under drought and other abiotic stresses. Analysis of transcriptomics data in studies, obtained from plants such as Arabidopsis thaliana exposed to drought stress have revealed a lot about plant responses to abiotic stresses. Genetic, molecular and biochemical studies have been conducted over the years in order to identify key regulators in plant drought response. Many regulators such as Transcription Factors (TFs) have been examined over the years in order to verify their roles in the enhancement of abiotic stress tolerance i.e.: drought in crops all over the world. Recent work has revealed Gene Regulatory Networks using Variational Bayesian State Space Modelling, obtained from time-series slow drying microarray data. These Gene Regulatory Networks unveiled various Transcription Factors such as BHLH038 closely related to AGL22 a key hub gene for drought response in Arabidopsis as identified by Bechtold et al. (2016), indicating the significant role of TF genes in drought stress signaling. In this review, we focused on unveiling the role of BHLH038 TF gene in drought stress response of Arabidopsis plants. Loss-of function mutants were phenotyped under drought conditions both in soil and plate-based medium. Only bhlh038-2 revealed a drought phenotype under plate-based assays in early developmental stages of Arabidopsis seedlings, whilst bhlh08-4 revealed a drought phenotype in slow-drying soil experiments in late growth stages of Arabidopsis plants. Network connections between BHLH038 and other closely related TF genes were tested by qPCR. BHLH038 can be considered as a key regulatory gene in drought stress signaling, further investigation would be beneficial.