Periodic Reporting for period 2 - TerreStriAL (Terrestrialization: Stress Signalling Dynamics in the Algal Progenitors of Land Plants)
Período documentado: 2021-05-01 hasta 2022-10-31
Land plants are what constitutes our macroscopic flora—from bogs of mosses to fields of cereal crops to forests of towering trees. Plant terrestrialization marks the birth of land plants. It describes the evolutionary process in which streptophyte algae established a thriving population in the terrestrial habitat, thus creating the foundation for macroscopic life on land and forever changing the face of our planet. Our rationale is that a cornerstone in the success of plant terrestrialization was an adequate response to environmental challenges. Terrestrial stressors. In project TerresStriAL, we investigate genes and genomes to learn about shared molecular mechanisms of extant plants and algae related to responding environmental cues that are characteristic of the terrestrial environment. We use these data to infer what molecular toolkit was present in the last common ancestor of land plants and algae to successfully overcome terrestrial stressors. Our work sheds light on the deep evolutionary root of plant physiology.
Work on the project falls into three major categories that concertedly shed light on the evolution of plant stress physiology: (i) stress experiments on streptophyte algae—which include the closest algal relatives of land plants, (ii) scrutinization of key molecular switches, including specific compounds and proteins, and (iii) large-scale analyses of new and publicly available sequencing data. All results are integrated in an evolutionary framework, mainly by means of computational biological tools and theoretical work. We have performed several rounds of experimental work to elucidate how the closest algal relatives of land plants respond to environmental challenges, revealing a range of molecular responses conserved across about 600 million years of evolution; we published some of these results already, some we are currently wrapping up. Through comparative computational approaches, we have recreated blueprints of what biosynthetic capacities the earliest land plants might have had, e.g. with regard to producing important phenolics. These insights were and will be further aided by data on the entire heritable material (genome) of extant streptophyte algae. Here we have generated a series of new genomic data, filling important gaps in the streptophyte tree of life; some of these genomes are close to publication. We have learned about the deep evolutionary origins of a key phytohormone signaling cascade (the stress hormone abscisic acid); this cascade likely first emerged as a phytohormone-independent signaling cascade that was brought under hormonal control during plant terrestrialization. An unexpected finding of our high-throughput investigations was that some of the streptophyte algae most distantly related to land plants contain a higher species diversity than previously thought. In theoretical work published in several articles, we continuously discuss our findings alongside the findings by the scientific community in light of the deep evolutionary roots of key plant traits.
Owing to seminal work that was carried out prior to project TerreStriAL by the international community of plant evolutionary biology, we have a good understanding of the relationships between land plants and algae. This knowledge allowed us to take a deep dive into the molecular physiology of the most informative species in order to understand the deep evolutionary roots of decisive features of plant molecular biology. Our data garnered so far have shed light on the conservation and evolutionary origin of several pathways and cascades that underpin hallmark traits of plant physiology, such as pathways that lead to the production of thousands of plant phenolics and signaling cascades that regulate thousands of genes. Until the end of the project we anticipate to illuminate what workable molecular programs have evolved that differ in streptophyte algae as compared to land plants. These data will shed light on the paths and versatility in streptophyte evolution.