Project Details
Projekt
Co-evolution of gametophytic communication systems by RALF, EA1 and ROS signaling
Applicant
Professor Dr. Thomas Dresselhaus
Subject Area
Plant Cell and Developmental Biology
Evolution and Systematics of Plants and Fungi
Evolution and Systematics of Plants and Fungi
Term
since 2021
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 431732981
The evolution of gametes, gametophytes and the sexual organs of land plants was accompanied by numerous adaptations of gametic/gametophytic communication systems. Notably, the adaptation of gymnosperms and angiosperms to arid environments was accompanied by a decline in sperm cell motility, the evolution of pollen grains (male gametophyte) that offer protection, and the transition from direct cross-talk between mobile gametes in green algae towards male and female gametophytes. Furthermore, novel and more intricate communication mechanisms of pollen and their tubes with female reproductive structures, such as transmitting tracts and ovules, emerged. Consequently, we hypothesize that gametophytic communication systems in angiosperms evolved rapidly and diversely due to the necessity for species-specific mechanisms to recognize self and to reject alien gametophytes/gametes. Furthermore, we hypothesize that mutations in these mechanisms represent a driving force of speciation, contributing to the multitude of angiosperm species. In the initial ICIPS funding phase, the focus is on the (co-)evolution, expansion and function of RALF (Rapid ALkalinization Factor) signaling peptide family members specifically expressed in pollen/pollen tubes. A comparison of the mechanisms between Arabidopsis, maize and basal land plants is also undertaken. Furthermore, we are examining their interactions with receptors belonging to the CrRLK1L family, LLG co-receptors and LRX cell wall proteins. In addition, work has commenced on the evolution of a distinct signaling peptide class in grasses (EA1-box peptides; EA1s), unrelated to RALFs, which are capable of interacting with the same CrRLK1L receptor. In the second funding phase, the objective is to understand the evolution and function of the EA1-box by conducting studies of uncharacterized EA1-box-containing proteins expressed in egg cells and zygotes. The competitive and/or collaborative binding of RALFs and EA1s to the same receptor and/or novel receptors shall be studied as well as their activation of different membrane-localized NADPH oxidases (respiratory burst oxidase homologs, RBOHs in plants) as putative downstream targets generating reactive oxygen species (ROS). In summary, the objective of this project is threefold: firstly, to enhance our understanding of how gametophytic signaling pathways are conserved across various plant species; secondly, to explore how peptide ligands evolved to interact with both existing and novel receptors; and thirdly, to investigate how novel signaling molecules have evolved in the grasses. Additionally, within the scope of collaborative project A (CP-A), this project aims to elucidate (iv) whether the transition from mobile to immobile sperm cells is associated with a loss or gain of secreted signaling peptides.
DFG Programme
Research Units
