Chloroplast relocation movement in the liverwort Apopellia endiviifolia

Abstract

Changes in the subcellular localisation of chloroplasts help optimise photosynthetic activity under different environmental conditions. In many plants, this movement is mediated by the blue-light photoreceptor phototropin. A model organism with simple phototropin signalling that allows clear observation of chloroplasts would facilitate the study of chloroplast relocation movement. Here, we examined this process in the simple thalloid liverwort Apopellia endiviifolia. Transverse sections of the thallus tissue showed uniformly developed chloroplasts and no air chambers; these characteristics enable clear observation of chloroplasts and analysis of their movements under a fluorescence stereomicroscope. At 22 C, the chloroplasts moved to the anticlinal walls of cells next to the neighbouring cells in the dark (dark-positioning response), whereas they moved towards weak light (accumulation response) and away from strong light (avoidance response). When the temperature was reduced to 5 C, the chloroplasts moved away from weak light (cold-avoidance response). Hence, both light-and temperature-dependent chloroplast relocation movements occur in A. endiviifolia. Notably, the accumulation, avoidance and cold-avoidance responses were induced under blue-light but not under red-light. These results suggest that phototropin is responsible for chloroplast relocation movement in A. endiviifolia and that the characteristics are similar to those in the model liverwort Marchantia polymorpha. RNA sequencing and Southern blot analysis identified a single copy of the PHOTOTROPIN gene in A. endiviifolia, indicating that a simple phototropin signalling pathway functions in A. endiviifolia. We conclude that A. endiviifolia has great potential as a model system for elucidating the mechanisms of chloroplast relocation movement. | INTRODUCTIONChloroplasts are organelles that perform photosynthesis to sustain plant growth and development. The intracellular locations of chloroplasts change in response to the ambient environments, a process that is important for the optimisation of light utilisation for photosynthesis.Various types of chloroplast relocation movement in response to environmental conditions (e.g., light and temperature) have been reported in model plants such as the thale cress Arabidopsis thaliana, the fern Adiantum capillus-veneris, the moss Physcomitrella patens and the

Organellar Glue: A Molecular Tool to Artificially Control Chloroplast–Chloroplast Interactions

“…In plant cells, organellar interactions have been observed in response to changes in ambient environmental conditions such as light and temperature. − These organellar interactions, driven by changes in the surrounding environment, are involved in various cellular processes, such as metabolite exchange, but their exact roles were unknown due to the lack of a means of artificially manipulating interactions between organelles. The ORGL technology will pave the way to studying metabolite exchange mediated by organellar interactions.…”

“…Plant organelles physically interact to facilitate many cellular processes in response to changes in environmental conditions. Chloroplast–chloroplast interactions, also known as chloroplast aggregation, are induced in response to cold temperatures in diverse plant species such as the liverworts Marchantia polymorpha and Apopellia endiviifolia , the Southern maidenhair fern ( Adiantum capillus-veneris ), and the gymnosperm Japanese yew ( Taxus cuspidata ). − In the light, chloroplasts physically interact with peroxisomes and mitochondria. , Various organelles, such as chloroplasts, mitochondria, and peroxisomes, share metabolic pathways and appear to exchange metabolites via direct physical contact . The artificial control of these organellar interactions would offer means to manipulate metabolic pathways such as photorespiration for basic research or engineering purposes.…”

“…Chloroplast–chloroplast interactions, also known as chloroplast aggregation, are induced in response to cold temperatures in diverse plant species such as the liverworts Marchantia polymorpha and Apopellia endiviifolia , the Southern maidenhair fern ( Adiantum capillus-veneris ), and the gymnosperm Japanese yew ( Taxus cuspidata ). 1 − 4 In the light, chloroplasts physically interact with peroxisomes and mitochondria. 5 , 6 Various organelles, such as chloroplasts, mitochondria, and peroxisomes, share metabolic pathways and appear to exchange metabolites via direct physical contact.…”

The localization of phototropin to the plasma membrane defines a cold-sensing compartment in Marchantia polymorpha

“…Marchantia polymorpha was asexually maintained on half-strength B5 medium with 1% (w/v) agar (BOP, SSK Sales Co., Ltd., Shizuoka, Japan) under approximately 70 µmol photons m –2 s –1 continuous white fluorescent light in the culture room at 22°C ( 38 ). The light spectrum of the white fluorescent light was previously reported ( 39 ). The male accession Takaragaike-1 (Tak-1) was used as the wild type.…”

Selection of a histidine auxotrophic <i>Marchantia polymorpha</i> strain with an auxotrophic selective marker

“…The cDNA fragment encoding part of the elongation factor was also amplified as an internal control with the primers 5′-GCA TCT TGT CTT CTG AAA GGT TGT C-3′ and 5′-CAC GCT TGT CAA TAC CTC CCA GCT TGT AGA TAA GG-3′. MpIGPD (or MpIGPDm) transcript levels in Mpigpd and MpIGPDm/Mpigpd were calculated via comparison with transcript levels in BC3-38 using the ∆∆Ct method as described previously (Yong et al 2021).…”