Biology subjects

Alfs, C.

Publications and source records attributed to Alfs, C..

3 recordsLinked to original sources

bioRxiv2026

Myosin-Driven Nuclear Movement Generates Stromules in Arabidopsis thaliana

Plastids form stroma-filled tubular extensions, termed stromules, that are implicated in inter-organellar communication. In pathogen-challenged Nicotiana benthamiana, stromule formation is driven by kinesins acting along microtubules. However, whether this mechanism also operates in unstressed plants or in other species remains unknown. Using systematic genetic analysis of all class XI myosin genes and quantitative time-lapse imaging in Arabidopsis (Arabidopsis thaliana), we show that basal stromule formation is predominantly myosin dependent through two distinct mechanisms. Myosin XI-I generates most stromules by driving oscillatory nuclear movement that mechanically pulls stromules from stationary plastids within the approx. 8m wide stromule-promoting zone. Myosins XI-K, XI-1, and XI-2 additionally drive a movement-independent, nucleus-associated stromule subpopulation within the same zone, establishing two mechanistically distinct pathways. We propose that movement-coupled stromules function as dynamic tethers maintaining plastid-nucleus proximity during nuclear oscillations, while movement-independent stromules expand the plastid membrane area within the perinuclear space, increasing the potential contact surface with the nucleus and surrounding environment. Together, both populations are proposed to enhance signal and metabolite exchange at the plastid-nucleus interface. These findings indicate that stromule biogenesis is both mechanistically and functionally context dependent, challenging the universality of the kinesin-microtubule model across plant species and physiological states.

plant biology↗

bioRxiv2021

Bacterial-type plant ferroxidases tune local phosphate sensing in root development

Fluctuating bioavailability of inorganic phosphate (Pi), often caused by complex Pi-metal interactions, guide root tip growth and root system architecture for maximizing the foraged soil volume. Two interacting genes in Arabidopsis thaliana, PDR2 (P5-type ATPase) and LPR1 (multicopper oxidase), are central to external Pi monitoring by root tips, which is modified by iron (Fe) co-occurrence. Upon Pi deficiency, the PDR2-LPR1 module facilitates cell type-specific Fe accumulation and cell wall modifications in root meristems, inhibiting intercellular communication and thus root growth. LPR1 executes local Pi sensing, whereas PDR2 restricts LPR1 function. We show that native LPR1 displays specific ferroxidase activity and requires a conserved acidic triad motif for high-affinity Fe2+ binding and root growth inhibition under limiting Pi. Our data indicate that substrate availability tunes LPR1 function and implicate PDR2 in maintaining Fe homeostasis. LPR1 represents the prototype of an ancient ferroxidase family, which evolved very early upon bacterial colonization of land. During plant terrestrialization, horizontal gene transfer transmitted LPR1-type ferroxidase from soil bacteria to the common ancestor of Zygnematophyceae algae and embryophytes, a hypothesis supported by homology modeling, phylogenomics, and activity assays of bacterial LPR1-type multicopper oxidases.

plant biology↗

bioRxiv2017

Phytophthora palmivora establishes tissue-specific intracellular infection structures in the earliest divergent land plant lineage

The expansion of plants onto land was a formative event that brought forth profound changes to the Earths geochemistry and biota. Filamentous eukaryotic microbes developed the ability to colonize plant tissues early during the evolution of land plants, as demonstrated by intimate symbiosis-like associations in >400 million-year-old fossils. However, the degree to which filamentous microbes establish pathogenic interactions with early divergent land plants is unclear. Here, we demonstrate that the broad host-range oomycete pathogen Phytophthora palmivora colonizes liverworts, the earliest divergent land plant lineage. We show that P. palmivora establishes a complex tissue-specific interaction with Marchantia polymorpha, where it completes a full infection cycle within air chambers of the dorsal photosynthetic layer. Remarkably, P. palmivora invaginates M. polymorpha cells with haustoria-like structures that accumulate host cellular trafficking machinery and the membrane-syntaxin MpSYP13B but not the related MpSYP13A. Our results indicate that the intracellular accommodation of filamentous microbes is an ancient plant trait that is successfully exploited by pathogens like P. palmivora.

plant biology↗