Robust control of floral meristem determinacy by position-specific multifunctions of KNUCKLES

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 118; no. 36; pp. 1 - 11
• Main Authors: Shang, Erlei, Wang, Xin, Li, Tinghan, Guo, Fengfei, Ito, Toshiro, Sun, Bo
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 07.09.2021
• Subjects: Arabidopsis - metabolism; Arabidopsis Proteins - metabolism; Biological Sciences; Carrier Proteins - metabolism; Control theory; Developmental stages; Feedback loops; Flowers - cytology; Flowers - metabolism; Homeodomain Proteins - metabolism; Maintenance; Meristem - metabolism; Meristems; Organs; Protein Binding; Repressor Proteins - metabolism; Robust control; Signal Transduction; Stem cells; Stem Cells - metabolism; Transcription; Zinc finger proteins; WUS; floral meristem; CLV3
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.2102826118

Floral organs are properly developed on the basis of timed floral meristem (FM) termination in Arabidopsis. In this process, two known regulatory pathways are involved. The WUSCHEL (WUS)-CLAVATA3 (CLV3) feedback loop is vital for the spatial establishment and maintenance of the FM, while AGAMOUS (AG)-WUS transcriptional cascades temporally repress FM. At stage 6 of flower development, a C2H2-type zinc finger repressor that is a target of AG, KNUCKLES (KNU), directly represses the stem cell identity gene WUS in the organizing center for FM termination. However, how the robust FM activity is fully quenched within a limited time frame to secure carpel development is not fully understood. Here, we demonstrate that KNU directly binds to the CLV1 locus and the cis-regulatory element on CLV3 promoter and represses their expression during FM determinacy control. Furthermore, KNU physically interacts with WUS, and this interaction inhibits WUS from sustaining CLV3 in the central zone. The KNU–WUS interaction also interrupts the formation ofWUS homodimers and WUS–HAIRYMERISTEM 1 heterodimers, both of which are required for FM maintenance. Overall, our findings describe a regulatory framework in which KNU plays a position-specific multifunctional role for the tightly controlled FM determinacy.