ABA INSENSITIVE 2 promotes flowering by inhibiting OST1/ABI5-dependent FLOWERING LOCUS C transcription in Arabidopsis

The plant hormone abscisic acid (ABA) is an important regulator of plant growth and development and plays a crucial role in both biotic and abiotic stress responses. ABA modulates flowering time, but the precise molecular mechanism remains poorly understood. Here we report that ABA INSENSITIVE 2 (AB...

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Published in:Journal of experimental botany 2024-04, Vol.75 (8), p.2481-2493
Main Authors: Ali, Akhtar, Zareen, Shah, Park, Junghoon, Khan, Haris Ali, Lim, Chae Jin, Bader, Zein Eddin, Hussain, Shah, Chung, Woo Sik, Gechev, Tsanko, Pardo, Jose M, Yun, Dae-Jin
Format: Article
Language:English
Subjects:
Abscisic Acid - metabolism
Arabidopsis - metabolism
Arabidopsis Proteins - genetics
Arabidopsis Proteins - metabolism
Basic-Leucine Zipper Transcription Factors - metabolism
Gene Expression Regulation, Plant
Phosphorylation
Plant Growth Regulators - metabolism
Protein Kinases - metabolism
Research Papers
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Summary:The plant hormone abscisic acid (ABA) is an important regulator of plant growth and development and plays a crucial role in both biotic and abiotic stress responses. ABA modulates flowering time, but the precise molecular mechanism remains poorly understood. Here we report that ABA INSENSITIVE 2 (ABI2) is the only phosphatase from the ABA-signaling core that positively regulates the transition to flowering in Arabidopsis. Loss-of-function abi2-2 mutant shows significantly delayed flowering both under long day and short day conditions. Expression of floral repressor genes such as FLOWERING LOCUS C (FLC) and CYCLING DOF FACTOR 1 (CDF1) was significantly up-regulated in abi2-2 plants while expression of the flowering promoting genes FLOWERING LOCUS T (FT) and SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1) was down-regulated. Through genetic interactions we further found that ost1-3 and abi5-1 mutations are epistatic to abi2-2, as both of them individually rescued the late flowering phenotype of abi2-2. Interestingly, phosphorylation and protein stability of ABA INSENSITIVE 5 (ABI5) were enhanced in abi2-2 plants suggesting that ABI2 dephosphorylates ABI5, thereby reducing protein stability and the capacity to induce FLC expression. Our findings uncovered the unexpected role of ABI2 in promoting flowering by inhibiting ABI5-mediated FLC expression in Arabidopsis.
ISSN:0022-0957
1460-2431
1460-2431
DOI:10.1093/jxb/erae029