IAB IMOSS SEB

The position of bryophytes as the closest extant relatives of the first land plants has long been widely accepted. However unequivocal affirmation of their order of divergence and whether or not they constitute a monophyletic group remain elusive. The last fifty years have witnessed a succession of hypotheses gaining general acceptance only to be discarded in the light of new evidence. The latest molecular studies now demonstrate strong support for a mosses-liverworts clade, or Setaphyta, with the position of hornworts remaining uncertain and monophyly gaining renewed support. I will explore how current hypotheses on the origin and evolution of key land plant innovations fit into these latest evolutionary scenarios, with a focus on bryophyte stomatal apparatus and fungal associations.

The golden jubilee of the International Association of Bryologists (IAB) is a suitable occasion to pay a tribute to those individuals who made outstanding early contributions to bryology and helped shaping the discipline. This symposium will focus on the lives, work and ideas of founders of bryology such as Johannes HEDWIG who first interpreted bryophytes as we understand them today (by Michelle Price), Wilhelm SCHIMPER whose anatomical work on mosses, especially Sphagnum, laid the foundation for our understanding of bryophyte biology (Jeffrey Duckett), Victor BROTHERUS who single-handedly produced the largest overview of the world’s mosses (Timo Koponen), Richard SPRUCE who produced the corner-stone of modern-day hepaticology and tropical bryology (Tamás Pócs), and finally, William SULLIVANT and Leo LESQUEREUX and the dawn of bryology in North America (Bernard Goffinet and Rafael Medina). The effectiveness of international collaboration among bryologists in documenting the global diversity of bryophytes, today more relevant than ever before, was first shown by mid-19th century bryologists in the framework of the Synopsis Hepaticarum and Bryologia Europea projects. We are grateful to these great early scholars; their pioneering work has shed first light on the structure and functioning of the most diverse group of early land plants inhabiting our planet: the bryophytes.

The radiation of life on Earth depended on the colonisation of land by plants. Plants’ photosynthetic activity enriched oxygen in the atmosphere, plants made the first soils and plants make food and homes for animals. The greening of the land started by the formation of thin soil crusts growing fungi, lichens and algae, and land plants originated from these algae. The first land plants had a single tiny stem capped in a reproductive structure, as in modern mosses and other bryophytes. In contrast, most of today’s plants have large and elaborate branching forms nourished by vascular transport. My lab’s research aims to identify genes and developmental changes that enabled such vascular plant forms to arise during evolution.

Tissue and organs are composed of cells, and the development and its evolution reflect the dynamics of cell behavior. However, genetic regulations of cellular characters and mechanisms especially deeply related to the evolution of land plant body plan have not been well studied. Bryophytes are appropriate materials because of its simple organization, feasibility to observe living cells, and its basal position in land plants. In mosses including Physcomitrella patens, development of each organ is initiated from a single stem cell with different characters each other. In this presentation, I will talk (1) induction of reprogramming of differentiated leaf cells to chloronema apical stem cells by AP2/ERF transcription factor STEMIN with chromatin modifications, (2) a potential role of STEMIN induced reprogramming in living under land environment, and (3) regulatory mechanisms of cell division axes in apical stem cells with auxin and its transporter.

Ultraviolet radiation (UVR) is one of many environmental factors that have contributed to the evolution of organisms since the very beginning of life on Earth. Bryophytes have also an outstanding evolutionary importance as the first “true” plants (embryophytes) colonizing the terrestrial environment and facing new challenges for photosynthetic organisms. Thus, the combination of bryophytes and UVR may give birth to a new and consistent corpus of science (bryophyte UV-omics) trying to explain the significance of UVR on the acclimation/adaptation of bryophytes to live on land. In this sense, bryophyte UV-omics would integrate methods, species, response variables, molecules, interacting environmental factors, evolution, and (why not?) applications. Overall, the balanced development of bryophyte UV-omics is demanding large doses of scientific collaboration in the frontiers of multifaceted bryology (and bryologists), from molecules to ecophysiology.

One crucial, upcoming challenge will be to conserve plant biodiversity under climate change. Botanist and ecologist have already accumulated extensive ecological knowledge on main plant groups, essentially trees, but much less in bryophytes. The contribution of ecological modelling (species distribution models and biodiversity models) to improve management decisions is especially relevant for the rest of plant groups. Anticipation to climate change effects relies on ecological models, and in order to face the challenge it impose we need: 1) to understand the climatic drivers of biodiversity, 2) to quantify these drivers in a model for current patterns, and 3) to predict future patterns using those models. But, what do we know about the drivers of biodiversity? Can we use this knowledge to predict future biodiversity patterns? Bryophytes, due to their poikilohydric nature and long-distance dispersal ability, are an ideal group to answer these questions and implement improved ecological models. The subsequent models are an effective tool widely applied in numerous disciplines, as conservation planning, assessment of climate change effects on biodiversity, reserve design, and biological invasions evaluations.