A decoy receptor derived from alternative splicing fine-tunes cytokinin signaling in Arabidopsis.

Hormone perception and signaling pathways have a fundamental regulatory function in the physiological processes of plants. Cytokinins, a class of plant hormones, regulate cell division and meristem maintenance. The cytokinin signaling pathway is well established in the model plant Arabidopsisthaliana.

The RALF signaling pathway regulates cell wall integrity during pollen tube growth in maize.

Autocrine signaling pathways regulated by RAPID ALKALINIZATION FACTORs (RALFs) control cell wall integrity during pollen tube germination and growth in Arabidopsis (Arabidopsis thaliana). To investigate the role of pollen-specific RALFs in another plant species, we combined gene expression data with phylogenetic and biochemical studies to identify candidate orthologs in maize (Zea mays). We show that Clade IB ZmRALF2/3 mutations, but not Clade III ZmRALF1/5 mutations, cause cell wall instability in the sub-apical region of the growing pollen tube.

RALF peptide signaling controls the polytubey block in .

Fertilization of an egg by multiple sperm (polyspermy) leads to lethal genome imbalance and chromosome segregation defects. In , the block to polyspermy is facilitated by a mechanism that prevents polytubey (the arrival of multiple pollen tubes to one ovule). We show here that FERONIA, ANJEA, and HERCULES RECEPTOR KINASE 1 receptor-like kinases located at the septum interact with pollen tube-specific RALF6, 7, 16, 36, and 37 peptide ligands to establish this polytubey block.

How CrRLK1L Receptor Complexes Perceive RALF Signals.

RALFs are secreted peptides that are perceived by various CrRLK1L-LRE/LLG receptor complexes. The mechanistic basis of this perception has now been elucidated showing that the co-receptor LLG binds RALF23 to nucleate a FER receptor complex. This interaction likely occurs in other tissues where RALFs meet CrRLK1L receptors and LRE/LLG co-receptors.

Cysteine-rich peptides promote interspecific genetic isolation in .

Reproductive isolation is a prerequisite for speciation. Failure of communication between female tissues of the pistil and paternal pollen tubes imposes hybridization barriers in flowering plants. LURE1 (AtLURE1) peptides and their male receptor PRK6 aid attraction of the growing pollen tube to the ovule.

Pollen tube integrity regulation in flowering plants: insights from molecular assemblies on the pollen tube surface.

Contents Summary 687 I. Introduction 687 II. Pollen tube membrane-localized receptors coordinate cell integrity and sperm release 689 III.

pollen tube integrity and sperm release are regulated by RALF-mediated signaling.

In flowering plants, fertilization requires complex cell-to-cell communication events between the pollen tube and the female reproductive tissues, which are controlled by extracellular signaling molecules interacting with receptors at the pollen tube surface. We found that two such receptors in , BUPS1 and BUPS2, and their peptide ligands, RALF4 and RALF19, are pollen tube-expressed and are required to maintain pollen tube integrity. BUPS1 and BUPS2 interact with receptors ANXUR1 and ANXUR2 via their ectodomains, and both sets of receptors bind RALF4 and RALF19.

Manipulating the Bacterial Cell Cycle and Cell Size by Titrating the Expression of Ribonucleotide Reductase.

Understanding how bacteria coordinate growth with cell cycle events to maintain cell size homeostasis remains a grand challenge in biology. The period of chromosome replication (C period) is a key stage in the bacterial cell cycle. However, the mechanism of regulation of the C period remains unclear.