Abscisic Acid and Gibberellins Antagonistically Mediate Plant Development and Abiotic Stress Responses

Abstract

Phytohormones regulate numerous important biological processes in plant development and biotic/abiotic stress response cascades. More than 50 and 100 years have passed since the initial discoveries of the phytohormones abscisic acid (ABA) and gibberellins (GA), respectively. Over the past several decades, numerous elegant studies have demonstrated that ABA and GA antagonistically regulate many plant developmental processes, including seed maturation, seed dormancy and germination, root initiation, hypocotyl and stem elongation, and floral transition. Furthermore, as a well-established stress hormone, ABA plays a key role in plant responses to abiotic stresses, such as drought, flooding, salinity and low temperature. Interestingly, recent evidence revealed that GA are also involved in plant response to adverse environmental conditions. Consequently, the complex crosstalk networks between ABA and GA, mediated by diverse key regulators, have been extensively investigated and documented. In this updated mini-review, we summarize the most recent advances in our understanding of the antagonistically regulatory roles of ABA and GA in different stages of plant development and in various plant–environment interactions, focusing on the crosstalk between ABA and GA at the levels of phytohormone metabolism and signal transduction.

A matter of life and death: Molecular, physiological, and environmental regulation of seed longevity

“…Phytohormones play key and distinct roles throughout the lifecycle, including seed dormancy, germination, and abiotic stress responses (Liu et al, ; Liu & Hou, ; Shu et al, ; Shu, Liu, Xie, & He, ; Shu, Zhou, Cheng, Luo, & Yang, ). It is widely recognized that ABA and GAs mediate seed dormancy and germination antagonistically (El‐Maarouf‐Bouteau & Bailly, ; Jeevan Kumar et al, ; Shu et al, ; Shu, Zhou, & Yang, ).…”

“…Seeds of the aba1‐5 mutant showed significantly shorter longevity under ambient storage conditions (Clerkx et al, ). However, although ABA and GA antagonistically regulated seed germination, seedling growth, and stress response (Shu, Zhou, Cheng, et al, ), seed longevity was not significantly affected in GA‐biosynthesis and/or ‐signaling mutants, including the GA‐deficient mutant ga1‐3 and the GA ‐insensitive mutant gai (Clerkx et al, ). Compared with the WT, the Arabidopsis ethylene‐insensitive mutant etr and the jasmonic acid‐insensitive mutant jar1‐1 showed no significant decrease in seed longevity after 4‐year storage (Clerkx et al, ).…”

The tomato DELLA protein PROCERA promotes ABA responses in guard cells by upregulating ABA transporter

“…The crosstalk between GA and ABA has been investigated for many years (Weiss and Ori, 2007; Shu et al, 2018). This crosstalk is largely depends on DELLA; DELLA promotes ABA synthesis and signaling and ABA promotes DELLA stability and therefore, inhibits GA signaling (Achard et al, 2006; Piskurewicz et al, 2008; Lim et al, 2013; Liu et al, 2018).…”

“…In tomato, the lack of DELLA activity in seeds suppresses desiccation tolerance due to inhibition of ABA-induced gene expression (Livne et al, 2015). Taken together, these studies suggest that GA and ABA negatively interact at the hormone biosynthesis and signaling levels (Shu et al, 2018).…”

“…The crosstalk between GA and ABA has been studied for many years in numerous plant species (Piskurewicz et al, 2008; Liu et al, 2018, Shu et al, 2018). The transcription factor ABSCISIC ACID-INSENSITIVE 4 (ABI4) promotes seed dormancy in Arabidopsis by the suppression of GA accumulation and the promotion of ABA biosynthesis (Shu et al, 2013).…”