Table 1.
ABA–light integrative modules and their functional significance.
| Light signaling protein | ABA-responsive gene/protein | Signaling module | Function | References |
|---|---|---|---|---|
| HY5 | ABI5 | HY5 → ABI5 | ABA responses in seed germination, seedling growth, and root development | Chen et al., 2008 |
| H2O2 production via the activation of NADPH oxidase. Tolerance to excess light and cold | Zhou et al., 2014; Wang et al., 2018 | |||
| BBX21 | ABI5 | BBX21—‖ ABI5 | Gas exchange in drought conditions | Xu et al., 2014; Kang et al., 2018 |
| PIF1 | ABI3 and ABI5 | phyB —‖ PIF1 → ABI3 and ABI5 | Increased ABA responsiveness, inhibition of seed germination | Oh et al., 2009 |
| PIF1 PIF4 | ABI5 | ELF3 —‖ PIF4 → ABI5 | Leaf senescence at high ambient temperature | Sakuraba et al., 2014; Kim et al., 2020 |
| PIF1 PIF3 PIF4 PIF5 | PYL8/PYL9 | PYL8/PYL9 → PIF4 | PYL8 and PYL9 promote PIF4 protein accumulation in the dark and enhance PIF4 binding to the ABI5 promoter, but negatively regulate PIF4-mediated ABI5 activation | Qi et al., 2020 |
| PYL8/PYL9 —‖ PIF4 → ABI5 | ||||
| PIF3 PIF5 | PYL3, PYL6, PYL12, SnRK2.2, ABI5 and ABF3 | Potential targets indicated (further study of gene expression required) | Unknown | Liang et al., 2020 |
| FHY3 | ABI1, ABI3, ABI4 and ABI5 | DET1 —‖ FHY3 → ABI1, ABI3, ABI4 and ABI5 | Activation of the ABA pathway after the dark-to-light transition. Pathway repressor: DET1 | Xu et al., 2020 |
| DET1 | ABI5 | DET1 —‖ ABI5 (via recruiting HDA6 to ABI5 promoter) | Positive regulation of light-induced greening; epigenetic control of ABI5 expression | Xu et al., 2020 |
| CO | ABI3 | CO —‖ ABI3 | Quiescence in developing seedlings, rapid induction of flowering | Kurup et al., 2000 |
| phyB | SnRK2.6 | SnRK2.6-phyB | Negative role of SnRK2.6 in red light-induced stomatal opening | Li et al., 2021 |
| FCA | ABI5 | FCA → ABI5 | Adaptation of embryo and flower development to stress-induced ROS, heat, cold, and drought conditions | Lee et al., 2015 |
| LHY | ABI1, ABI2 | LHY —‖ ABI1/2 | Coupling between the circadian clock and ABA pathways | Adams et al., 2018 |
| SnRK2.2 | LHY —‖ SnRK2.2 | Activation of drought-tolerance processes | ||
| ABF1 | LHY —‖ ABF1 | Potentiation of ABA responses in the morning | ||
| ABI5 | LHY → ABI5 | Responses to unexpectedly hot or dry conditions in the daytime | ||
| FLC | ABI5 | SnRK2s → ABI5 (and/or other ABFs) → FLC | Inhibitory effect on floral transition | Wang et al., 2013 |
| ABI4 | ABI4 → FLC | Shu et al., 2016 |