期刊
PLANT JOURNAL
卷 107, 期 5, 页码 1346-1362出版社
WILEY
DOI: 10.1111/tpj.15383
关键词
Arabidopsis thaliana; BBX proteins; HY5; karrikin; light signaling
资金
- Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) [409212330, 320656366]
- National Science Foundation [IOS-1856741]
- Projekt DEAL
The butenolide molecule karrikin (KAR) enhances light responses in Arabidopsis through a signaling pathway involving KAI2, MAX2, SMAX1, SMXL2, HY5, BBX20, and BBX21. This pathway is responsible for regulating hypocotyl elongation and anthocyanin accumulation, with the HY5-BBX module playing a crucial role in mediating these responses. Light- and KAR-dependent signaling intersect at the HY5-BBX transcriptional module.
The butenolide molecule, karrikin (KAR), emerging in smoke of burned plant material, enhances light responses such as germination, inhibition of hypocotyl elongation, and anthocyanin accumulation in Arabidopsis. The KAR signaling pathway consists of KARRIKIN INSENSITIVE 2 (KAI2) and MORE AXILLARY GROWTH 2 (MAX2), which, upon activation, act in an SCF E3 ubiquitin ligase complex to target the downstream signaling components SUPPRESSOR OF MAX2 1 (SMAX1) and SMAX1-LIKE 2 (SMXL2) for degradation. How degradation of SMAX1 and SMXL2 is translated into growth responses remains unknown. Although light clearly influences the activity of KAR, the molecular connection between the two pathways is still poorly understood. Here, we demonstrate that the KAR signaling pathway promotes the activity of a transcriptional module consisting of ELONGATED HYPOCOTYL 5 (HY5), B-BOX DOMAIN PROTEIN 20 (BBX20), and BBX21. The bbx20 bbx21 mutant is largely insensitive to treatment with KAR(2), similar to a hy5 mutant, with regards to inhibition of hypocotyl elongation and anthocyanin accumulation. Detailed analysis of higher order mutants in combination with RNA-sequencing analysis revealed that anthocyanin accumulation downstream of SMAX1 and SMXL2 is fully dependent on the HY5-BBX module. However, the promotion of hypocotyl elongation by SMAX1 and SMXL2 is, in contrast to KAR(2) treatment, only partially dependent on BBX20, BBX21, and HY5. Taken together, these results suggest that light- and KAR-dependent signaling intersect at the HY5-BBX transcriptional module.
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