Dynamic changes in metabolism and protein population in response to glucose in P. patens.

What is it about?

Sugars act not only as substrates for plant metabolism, but also have a pivotal role in signaling pathways. Glucose signaling has been widely studied in the vascular plant Arabidopsis thaliana, but it has remained unexplored in non-vascular species such as Physcomitrella patens. To investigate P. patens response to high glucose treatment, we explored the dynamic changes in metabolism and protein population by applying a metabolomic fingerprint analysis (DIESI-MS), carbohydrate and chlorophyll quantification, Fv/Fm determination and label-free untargeted proteomics. Glucose feeding causes specific changes in P. patens metabolomic fingerprint, carbohydrate contents and protein accumulation, which is clearly different from those of osmotically induced responses. The maximal rate of PSII was not affected although chlorophyll decreased in both treatments. The biological process, cellular component, and molecular function gene ontology (GO) classifications of the differentially expressed proteins indicate the translation process is the most represented category in response to glucose, followed by photosynthesis, cellular response to oxidative stress and protein refolding. Importantly, although several proteins have high fold changes, these proteins have no predicted identity. The most significant discovery of our study at the proteome level is that high glucose increase abundance of proteins related to the translation process, which was not previously evidenced in non-vascular plants, indicating that regulation by glucose at the translational level is a partially conserved response in both plant lineages. To our knowledge, this is the first time that metabolome fingerprint and proteomic analyses are performed after a high sugar treatment in non-vascular plants. These findings unravel evolutionarily shared and differential responses between vascular and non-vascular plants

Featured Image

Photo by Emmanuel Mbala on Unsplash

Photo by Emmanuel Mbala on Unsplash

Why is it important?

In this study, we explored the metabolomic and proteomic responses of the non-vascular plant, P. patens, to high glucose levels. We found that glucose feeding causes specific changes in moss metabolomic fingerprint, carbohydrate contents, and protein accumulation, which differed from osmotically induced responses. Our most significant discovery at the proteome level is that high glucose-induced ribosomal proteins related to the translation process. It is worth noting that in the biological process, cellular component, and molecular function classifications, the categories including proteins related to translation are the most represented in response to glucose. Consistently, it is known that in plants such as Arabidopsis, growth and development responses to sugars depend on de novo protein synthesis and mRNA translation; however, this has not been previously evidenced in non-vascular plants. Moreover, the fact that glucose-induced proteins related to oxidative stress accumulate in P. patens under high glucose treatment, suggests that this plant possesses an efficient ROS scavenging system. This idea is supported by the results showing that the glucose treatment did not alter the maximal rate of PSII and the electron transport chain. In summary, even though A. thaliana and P. patens represent two evolutionary distant plant lineages, the fact that glucose feeding affects the translational level of regulation in both model plants supports that a partially conserved response to glucose might exist between vascular and non-vascular plants. On the other hand differential responses may well be explained by the distant phylogenetic relationship between both plant species, such mechanisms are pending for future research, particularly in mosses.

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