Plant phylogenetics: The never-ending cycle of evolutionary gains and losses

On the prospects of basal cognition research becoming fully evolutionary: promising avenues and cautionary notes

The research programme 'basal cognition' adopts an evolutionary perspective for studying biological cognition. This entails investigating possible cognitive processes in 'simple'-often non-neuronal-organisms as a means to discover conserved mechanisms and adaptive capacities underwriting cognition in more complex (neuronal) organisms. However, by pulling in the opposite direction of a tradition that views cognition as something that is unique to neuronal organisms, basal cognition has been met with a fair amount of scepticism by philosophers and scientists. The very idea of approaching cognition by way of investigating the behaviour and underlying mechanisms in, say, bacteria, has been seen as preposterous and harmful to both cognitive science and biology. This paper aims to temper such scepticism to a certain degree by drawing parallels with how the evolution of 'development,' another loaded concept that refers to a not-so-easily definable, contested bundle of phenomena, has been fruitfully approached in Evolutionary Developmental Biology (Evo-Devo). Through this comparison, we identify four promising features of the basal cognition approach. These features suggest that sweeping scepticism may be unwarranted. However, each of them comes with important epistemic cautionary notes that should not be disregarded. By presenting these twofold considerations as potential ways to integrate a fully evolutionary perspective into basal cognition, this paper seeks to provide clarity and direction for the advancement of this research programme.

Diversified molecular adaptations of inorganic nitrogen assimilation and signaling machineries in plants

Plants evolved sophisticated machineries to monitor levels of external nitrogen supply, respond to nitrogen demand from different tissues and integrate this information for coordinating its assimilation. Although roles of inorganic nitrogen in orchestrating developments have been studied in model plants and crops, systematic understanding of the origin and evolution of its assimilation and signaling machineries remains largely unknown. We expanded taxon samplings of algae and early-diverging land plants, covering all main lineages of Archaeplastida, and reconstructed the evolutionary history of core components involved in inorganic nitrogen assimilation and signaling. Most components associated with inorganic nitrogen assimilation were derived from the ancestral Archaeplastida. Improvements of assimilation machineries by gene duplications and horizontal gene transfers were evident during plant terrestrialization. Clusterization of genes encoding nitrate assimilation proteins might be an adaptive strategy for algae to cope with changeable nitrate availability in different habitats. Green plants evolved complex nitrate signaling machinery that was stepwise improved by domains shuffling and regulation co-option. Our study highlights innovations in inorganic nitrogen assimilation and signaling machineries, ranging from molecular modifications of proteins to genomic rearrangements, which shaped developmental and metabolic adaptations of plants to changeable nutrient availability in environments.

A year at the forefront of plasmodesmal biology

Cell-cell communication is a central feature of multicellular organisms, enabling division of labour and coordinated responses. Plasmodesmata are membrane-lined pores that provide regulated cytoplasmic continuity between plant cells, facilitating signalling and transport across neighboring cells. Plant development and survival profoundly depend on the existence and functioning of these structures, bringing them to the spotlight for both fundamental and applied research. Despite the rich conceptual and translational rewards in sight, however, the study of plasmodesmata poses significant challenges. This Review will mostly focus on research published between May 2022 and May 2023 and intends to provide a short overview of recent discoveries, innovations, community resources and hypotheses.