The Plant Journal
Molecular link between energy production in plants and their stress response identified
IAL researchers study plants with reduced levels of cytochrome c (CYTc) and their response to growth and stress through changes in the activity of the SnRK1 pathway.
Researchers from the Molecular Biology Laboratory of the IAL (CONICET-UNL) analyse the relationship between the main source of energy in plants - mitochondrial energy - and two central pathways that regulate development and growth: "Two well-known players in connecting growth and stress responses based on the availability of nutritional resources are the target proteins rapamycin kinases (TOR) and SNF1/AMPK-related protein kinase 1 (SnRK1)," they say in the research. Through this study they found a link between mitochondrial activity and the two growth pathways, mainly SnRK1 with its respective stress response.
In plants, the primary source of energy is photosynthesis, which also involves the synthesis of carbon compounds that are stored for use in the absence of light. Energy production from these reserves occurs in the mitochondria via oxidative phosphorylation (OXPHOS) - a respiratory chain-dependent process - involving respiratory complexes and electron transporters such as ubiquinone and cytochrome c (CYTc). In other words, CYTc is a protein that acts as an electron transporter in the mitochondrial electron transport chain.
Florencia Coronel, a CONICET doctoral fellow and one of the authors of the paper published in The Plant Journal explains that CYTc is a small protein in the mitochondrial transport chain (movement of molecules in and out of the mitochondrion) that, in addition to its canonical function as an electron transporter, is also intimately related to plant growth and development: "Previous work in the lab has observed that CYTc mutant plants are smaller plants, which have deficits in growth and development, while over-expressing plants have the opposite phenotype. With these studies in mind, we set out to study whether there was a relationship between CYTc and two central pathways that regulate growth and development in plants (TOR OR SnRK1)," says the member of the IAL's Molecular Biology Laboratory.
Furthermore, specialists point out that plants are organisms that are sensitive to changes in the surrounding environment and for this they use regulatory mechanisms that allow them to optimise their resources according to their needs. In other words, "when plants are in optimal conditions for growth and development, they allocate a large part of their resources to induce growth, while when they face a stressful situation, they optimise resources to induce stress responses," they say.
The TOR pathway induces growth in plants under optimal conditions, while the SnRK1 pathway is activated under stress conditions, slows down the growth machinery and induces stress responses. Florencia Coronel, who is currently in her 5th year of a doctoral fellowship under the direction of Dr Daniel Gonzalez and Dr Elina Welchen, explains that they are analysing the relationship with stress through trials with CYTc mutant plants and wild-type (WT) plants subjected to osmotic stress, as this response has been shown to be closely related to increased SnRK1 protein activity. The results show that the growth of CYTc-deficient plants is less affected than that of wild-type plants, as is the case in plants possessing the more active SnRK1 pathway. On the other hand, when SnRK1 activity was decreased in CYTc mutant plants, it was observed that they were able to recover their wild-type phenotype, accompanied by an increase in TOR activity.
The assays were carried out on Arabidopsis thaliana (model organisms used), in the Laboratory of Molecular Biology of the IAL, CONICET-UNL are developing new lines of research to observe the behaviour in plants on CYTc expressors in rice, maize and soybean and to analyse their biotechnological applicability.
