title: The Role and Regulation of ABI5 (ABA-Insensitive 5) in Plant Development, Abiotic Stress Responses and Phytohormone Crosstalk.
abstract: ABA Insensitive 5 (ABI5) is a basic leucine zipper transcription factor that plays a key role in the regulation of seed germination and early seedling growth in the presence of ABA and abiotic stresses. ABI5 functions in the core ABA signaling, which is composed of PYR/PYL/RCAR receptors, PP2C phosphatases and SnRK2 kinases, through the regulation of the expression of genes that contain the ABSCISIC ACID RESPONSE ELEMENT (ABRE) motif within their promoter region. The regulated targets include stress adaptation genes, e.g., LEA proteins. However, the expression and activation ofABI5is not only dependent on the core ABA signaling. Many transcription factors such as ABI3, ABI4, MYB7 and WRKYs play either a positive or a negative role in the regulation ofABI5expression. Additionally, the stability and activity of ABI5 are also regulated by other proteins through post-translational modifications such as phosphorylation, ubiquitination, sumoylation andS-nitrosylation. Moreover, ABI5 also acts as an ABA and other phytohormone signaling integrator. Components of auxin, cytokinin, gibberellic acid, jasmonate and brassinosteroid signaling and metabolism pathways were shown to take part inABI5regulation and/or to be regulated by ABI5. Monocot orthologs ofAtABI5have been identified. Although their roles in the molecular and physiological adaptations during abiotic stress have been elucidated, knowledge about their detailed action still remains elusive. Here, we describe the recent advances in understanding the action of ABI5 in early developmental processes and the adaptation of plants to unfavorable environmental conditions. We also focus on ABI5 relation to other phytohormones in the abiotic stress response of plants.
authors.affiliation: Department of Genetics, Faculty of Biology and Environmental Protection, University of Silesia Katowice, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Skubacz
authors.affiliation: Department of Genetics, Faculty of Biology and Environmental Protection, University of Silesia Katowice, Poland.
authors.forename: Agata
authors.initials: A
authors.lastname: Daszkowska-Golec
authors.affiliation: Department of Genetics, Faculty of Biology and Environmental Protection, University of Silesia Katowice, Poland.
authors.forename: Iwona
authors.initials: I
authors.lastname: Szarejko
keywords: ABI5; abiotic stress response; abscisic acid; brassinosteroids; gibberellin acid; jasmonates; phytohormone crosstalk; posttranslational modification