Abscisic acid regulated gene expression in bread wheat (Triticum aestivum L.)

The studies about the elucidation of molecular components of drought response in major crops have become an urgent priority. Since abscisic acid (ABA) is one of the major plant hormones influencing main stress responses including drought, cold, and heat, there has been overwhelming interest in investigation of ABA-associated genes. Therefore, the identification and characterization of ABA-associated genes from bread wheat is significant for gaining better insights about the multiple stress-response mechanisms. Due to the pivotal role of ABA in stress response mechanism, we tried to determine spatiotemporal expressional characteristics of ABA-related genes in wheat. The comparative differential transcript profiling experiments revealed a total of 60 differentially-regulated cDNA fragments, thirty of which were sequenced to obtain more details about their functional identities. Some of the sequenced fragments showed significant similarity with the genes known to be associated with ABA-induced signaling networks; e. g., Germin-Like Proteins, Tonoplast Intrinsic Proteins, MAP kinases and leucine-rich repeat (LRR) receptor-like proteins. To get more details about ABA-associated genes in wheat, the expressional characteristics of the transcripts from the initial screening was further investigated by using quantitative Real Time PCR. For example, the amount of transcripts MAPK4 and TIP1 homologs in leaf tissue of bread wheat is gradually increased and eventually peaked in about 2 hours after ABA treatment, and subsequently declined with the prolonged exposure. On the other hand, induction in the GLP homolog expression was much faster than the aforementioned transcripts; reaching to the apex in roughly an hour after the treatment. This study provided insights about the expressional characteristics of some ABA-associated genes from bread wheat. This is the first study investigating the early response genes under ABA-treatment in hexaploid bread wheat.