Arabidopsis uses a molecular grounding mechanism and a biophysical circuit breaker to limit floral abscission signaling

• 成果类型: Article
• 署名作者: Taylor, Isaiah W.; Patharkar, O. Rahul; Mijar, Medhavinee; Hsu, Che-Wei; Baer, John; Niederhuth, Chad E.; Ohler, Uwe; Benfey, Philip N.; Walker, John C.
• 署名单位: Duke University; Washington University (WUSTL); Michigan State University; Helmholtz Association; Max Delbruck Center for Molecular Medicine; University of Missouri System; University of Missouri Columbia
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-13656
• DOI: 10.1073/pnas.2405806121
• 发表日期: 2024-10-29
• 关键词: organ abscission; inflorescence-deficient; kinase; map; senescence; responses; dehiscence; peptide; genes; haesa

摘要

Abscission is the programmed separation of plant organs. It is widespread in the plant kingdom with important functions in development and environmental response. In Arabidopsis, abscission of floral organs (sepals, petals, and stamens) is controlled by two receptor- like protein kinases HAESA (HAE) and HAESA LIKE- 2 (HSL2), which orchestrate the programmed dissolution of the abscission zone connecting floral organs to the developing fruit. In this work, we use single- cell RNA sequencing to characterize the core HAE/HSL2 abscission gene expression program. We identify the MAP KINASE PHOSPHATASE-1/MKP1 gene as a negative regulator of this pathway. MKP1 acts prior to activation of HAE/HSL2 signaling to establish a signaling threshold required for the initiation of abscission. Furthermore, we use single- cell data to identify genes expressed in two subpopulations of abscission zone cells: those proximal and those distal to the plane of separation. We identify INFLORESCENCE DEFICIENT INABSCISSION/ IDA family genes, encoding activating ligands of HAE/HSL2, as enriched in distal abscission zone cells at the base of the abscising organs. We show how this expression pattern forms a biophysical circuit breaker whereby, when the organ is shed, the source of the IDA peptides is removed, leading to cessation of HAE/HSL2 signaling. Overall, this work provides insight into the multiple control mechanisms acting on the abscission- signaling pathway.