Project Details
Projekt
Coevolution and diversification of processes controlling apoplastic redox dynamics during land plant growth and fertility
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
Land plant evolution has shaped fundamental changes in the alternation of generations and reproductive modes. Whereas bryophytes possess a dominant haploid generation and fertilization occurs between flagellated spermatozoids and egg cells in archegonia on gametophytes, gametophytes in angiosperms are reduced to a low number of cells. Here, fertilization has become independent of free water, but requires the interaction of tip-growing pollen tubes with the embryo sac enclosed in the ovule (and carpel). Moreover, locally generated reactive oxygen species (ROS) serve cell wall remodelling and signalling processes on both the male and female side of reproduction. Thus, proteins mediating ROS-dependent mechanisms in land plant growth and fertility have likely diversified to underpin different functions. Respiratory Burst Oxidase Homologs (RBOHs) initiate local changes in ROS levels by generating extracellular superoxide. Subsequently, superoxide dismutation as well as reactions catalysed by secreted class III peroxidases set the balance between different ROS types as well as target molecule specificity. Here, superoxide, hydrogen peroxide and hydroxyl radical levels serve distinct biological functions in signalling and local oxidative processes, leading to polymer formation or loosening. Both RBOH as well as class III peroxidase protein families have largely expanded during land plant evolution pointing to sub- and neofunctionalization and potentially coevolution. It is largely unknown (1) if extracellular redox dynamics are involved in the reproduction of flagellated plants and (2) how the balance between ROS-types downstream of RBOH shapes local redox dynamics in the different reproductive modes of land plants. This project will investigate (1) the sub-functionalisation and reproductive function of RBOH homologs in the model bryophyte Physcomitrium patens as well as (2) how extracellular enzymes determine the function of RBOH-dependent local superoxide formation. Here, we will investigate the effects that superoxide dismutation and/or lack of specific class III peroxidases with high expression in reproductive structures will have on plant growth and fertility. To monitor compartmentalised redox dynamics in vivo, we will employ and further develop methods for intracellular and extracellular sensing of local ROS generation during sexual reproduction in different land plant lineages, with a focus on genetically encoded redox biosensors. This project will enable a better understanding of the evolution of RBOH function in land plants as well as reveal the role of (coevolving) redox processes occurring downstream of RBOH activity.
DFG Programme
Research Units
