Biology subjects

Bonhomme, S.

Publications and source records attributed to Bonhomme, S..

3 recordsLinked to original sources

bioRxiv2023

Physcomitrium patens SMXL homologs are PpMAX2-dependent negative regulators of growth

SMXL proteins are a plant-specific clade of type I HSP100/Clp-ATPases. SMXL genes are found in virtually all land plant genomes. However, they have mainly been studied in angiosperms. In Arabidopsis thaliana, three SMXL functional subclades have been identified: SMAX1/SMXL2, SMXL345 and SMXL678. Out of these, two subclades ensure transduction of endogenous hormone signals: SMAX1/SMXL2 are involved in KAI2-ligand (KL) signaling, while SMXL678 are involved in strigolactone (SL) signaling. Many questions remain regarding the mode of action of these proteins, as well as their ancestral role. We addressed these questions by investigating the function of the four SMXL genes of the moss Physcomitrium patens. We demonstrate that PpSMXL proteins are involved in the conserved ancestral MAX2-dependent KL signaling pathway and act as negative regulators of growth. However, PpSMXL proteins expressed in A. thaliana unexpectedly cannot replace SMAX1/SMXL2 function in KL signaling, whereas they can functionally replace SMXL4/5 and restore root growth. Therefore, the molecular function of SMXL could be conserved, but not their interaction network. Moreover, one PpSMXL clade positively regulates transduction of the SL signal in P. patens. So far, this function has only been reported herein in moss, where it represents a novel crosstalk between SL and KL signaling pathways.

plant biology↗

bioRxiv2019

Design of a comprehensive microfluidic and microscopic toolbox for the ultra-wide spatio-temporal study of plant protoplasts development and physiology

BackgroundOne of the main features of plant cells is their strong plasticity, and their propensity to regenerate an organism from a single cell. Plant protoplasts are basic plant cells units in which the pecto-cellulosic cell wall has been removed, but the plasma membrane is intact. One of the main features of plant cells is their strong plasticity, which in some species, can be very close from what is defined as cell totipotency. Methods and differentiation protocols used in plant physiology and plant biology usually involve macroscopic vessels and containers that make difficult, for example, to follow the fate of the same protoplast all along its full development cycle, but also to perform continuous studies of the influence of various gradients in this context. These limits have hampered the precise study of regeneration processes. ResultsHerein, we present the design of a comprehensive, physiologically relevant, easy-to-use and low-cost microfluidic and microscopic setup for the monitoring of Physcomitrella patens (P. patens) growth and development on a long-term basis. The experimental solution we developed is made of two parts (i) a microfluidic chip composed of a single layer of about a hundred flow-through microfluidic traps for the immobilization of protoplasts, and (ii) a low-cost, light-controlled, custom-made microscope allowing the continuous recording of the moss development in physiological conditions. We validated the experimental setup with three proofs of concepts: (i) the kinetic monitoring of first division steps and cell wall regeneration, (ii) the influence of the photoperiod on growth of the protonemata, and (iii) finally the induction of leafy buds using a phytohormone, cytokinin. ConclusionsWe developed the design of a comprehensive, physiologically relevant, easy-to-use and low-cost experimental setup for the study of P. patens development in a microfluidic environment. This setup allows imaging of P. patens development at high resolution and over long time periods.

plant biology↗

bioRxiv2017

Green microalga Trebouxia sp. produces strigolactone-related compounds

Different algal species that may have germination inducing activity of holoparasitic broomrape weeds Phelipanche aegyptiaca and P. ramosa seeds were screened through germination bioassay. Green alga produce SL-related compounds. Applied extracts of biomass obtained from the culture of green alga Trebouxia arboricola increased seeds germination of both parasites. An optimatization of the alga extraction led to an increase of P. aegyptiaca germination. Exhausted medium also contained SL-related compounds. The crude extract stimulated the roots length of Arabidopsis thaliana tested in vitro. A similar effect had the algae and GR24 aplications on expression levels of the SL-related genes in Physcomitrella patens. The novel analytical method DESI-MSI detected production of carlactone in the algae. The Trebouxia sp. culture applications in pot experiments had positive effect on growth characteristics of pea plants.

plant biology↗