Endocytosis regulates the turnover of cell surface localized receptors, which are crucial for plants to rapidly respond to stimuli. The evolutionary ancient TPLATE complex (TPC) plays an essential role in endocytosis in Arabidopsis plants. Knockout or knockdown of single TPC subunits causes male sterility and seedling lethality phenotypes, complicating analysis of the roles of TPC during plant development. Partially functional alleles of TPC subunits however only cause mild developmental deviations. Here, we took advantage of the partially functional TPLATE allele, WDXM2, to investigate a role for TPC-dependent endocytosis in receptor-mediated signaling. We discovered that reduced TPC-dependent endocytosis confers a hypersensitivity to very low doses of CLAVATA3 peptide signaling. This hypersensitivity correlated with the abundance of the CLAVATA3 receptor protein kinase CLAVATA1 at the plasma membrane. Genetic and biochemical analysis as well as live-cell imaging revealed that TPC-dependent regulation of CLAVATA3-dependent internalization of CLAVATA1 from the plasma membrane is required for shoot stem cell homeostasis. Our findings provide evidence that TPC-mediated endocytosis and degradation of CLAVATA1 is a mechanism to dampen CLAVATA3-mediated signaling during plant development.
- Klíčová slova
- CLAVATA3-CLAVATA1 signaling, TPLATE complex, clathrin-mediated endocytosis, shoot apical meristem maintenance,
- MeSH
- Arabidopsis * genetika MeSH
- endocytóza MeSH
- meristém genetika MeSH
- proteiny huseníčku * genetika MeSH
- receptory buněčného povrchu metabolismus MeSH
- regulace genové exprese u rostlin MeSH
- rostliny metabolismus MeSH
- signální transdukce MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- CLV1 protein, Arabidopsis MeSH Prohlížeč
- proteiny huseníčku * MeSH
- receptory buněčného povrchu MeSH
- TPLATE protein, Arabidopsis MeSH Prohlížeč
Root, shoot, and lateral meristems are the main regions of cell proliferation in plants. It has been proposed that meristems might have evolved dedicated transcriptional networks to balance cell proliferation. Here, we show that basic helix-loop-helix (bHLH) transcription factor heterodimers formed by members of the TARGET OF MONOPTEROS5 (TMO5) and LONESOME HIGHWAY (LHW) subclades are general regulators of cell proliferation in all meristems. Yet, genetics and expression analyses suggest specific functions of these transcription factors in distinct meristems, possibly due to their expression domains determining heterodimer complex variations within meristems, and to a certain extent to the absence of some of them in a given meristem. Target gene specificity analysis for heterodimer complexes focusing on the LONELY GUY gene targets further suggests differences in transcriptional responses through heterodimer diversification that could allow a common bHLH heterodimer complex module to contribute to cell proliferation control in multiple meristems.
- Klíčová slova
- Biological sciences, Molecular plant pathology, Natural sciences, Plant biology,
- Publikační typ
- časopisecké články MeSH
Plants, in contrast to animals, are unique in their capacity to postembryonically develop new organs due to the activity of stem cell populations, located in specialized tissues called meristems. Above ground, the shoot apical meristem generates aerial organs and tissues throughout plant life. It is well established that auxin plays a central role in the functioning of the shoot apical meristem. Auxin distribution in the meristem is not uniform and depends on the interplay between biosynthesis, transport, and degradation. Auxin maxima and minima are created, and result in transcriptional outputs that drive the development of new organs and contribute to meristem maintenance. To uncover and understand complex signaling networks such as the one regulating auxin responses in the shoot apical meristem remains a challenge. Here, we will discuss our current understanding and point to important research directions for the future.
Auxin is a major plant growth regulator, but current models on auxin perception and signaling cannot explain the whole plethora of auxin effects, in particular those associated with rapid responses. A possible candidate for a component of additional auxin perception mechanisms is the AUXIN BINDING PROTEIN 1 (ABP1), whose function in planta remains unclear. Here we combined expression analysis with gain- and loss-of-function approaches to analyze the role of ABP1 in plant development. ABP1 shows a broad expression largely overlapping with, but not regulated by, transcriptional auxin response activity. Furthermore, ABP1 activity is not essential for the transcriptional auxin signaling. Genetic in planta analysis revealed that abp1 loss-of-function mutants show largely normal development with minor defects in bolting. On the other hand, ABP1 gain-of-function alleles show a broad range of growth and developmental defects, including root and hypocotyl growth and bending, lateral root and leaf development, bolting, as well as response to heat stress. At the cellular level, ABP1 gain-of-function leads to impaired auxin effect on PIN polar distribution and affects BFA-sensitive PIN intracellular aggregation. The gain-of-function analysis suggests a broad, but still mechanistically unclear involvement of ABP1 in plant development, possibly masked in abp1 loss-of-function mutants by a functional redundancy.
- Klíčová slova
- AUXIN BINDING PROTEIN 1 (ABP1), Auxin, Auxin signaling, Plant development,
- MeSH
- Arabidopsis růst a vývoj metabolismus MeSH
- hypokotyl růst a vývoj metabolismus MeSH
- konfokální mikroskopie MeSH
- kořeny rostlin růst a vývoj metabolismus MeSH
- kvantitativní polymerázová řetězová reakce MeSH
- kyseliny indoloctové metabolismus MeSH
- proteiny huseníčku metabolismus fyziologie MeSH
- protoplasty metabolismus MeSH
- receptory buněčného povrchu metabolismus fyziologie MeSH
- regulace genové exprese u rostlin MeSH
- regulátory růstu rostlin metabolismus fyziologie MeSH
- rostlinné proteiny metabolismus fyziologie MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- auxin-binding protein 1 MeSH Prohlížeč
- kyseliny indoloctové MeSH
- proteiny huseníčku MeSH
- receptory buněčného povrchu MeSH
- regulátory růstu rostlin MeSH
- rostlinné proteiny MeSH
