Growth-Stress NET will build signaling networks that allow rice plants to control their growth in response to environmental changes. It will identify key crosstalk hubs that allow the fine tuning of this process and explore their potential to be used as biotechnological tools.

In general, stress and metabolic signaling networks interact allowing plants to respond to biotic (herbivory and pathogen attack) and abiotic (drought, cold, heat and osmotic stresses including salinity) stresses. At the interface between these two major signaling systems are, among others, calcium-dependent protein kinases (CPKs). These are dual-action enzymes, capable of sensing the calcium signal arising from stress and transmitting the encoded information trough phosphorylation of downstream targets. In rice, CPKs are a family of 31 genes, and the Growth-Stress NET team showed the involvement of several of them in both biotic and abiotic stress response. In particularly, OsCPK17 was shown to be responsible for the phosphorylation of key enzymes in rice anabolic processes. Interestingly, some of these targets are themselves targets for sucrose non-fermenting-1 (SNF1) related kinase (SnRK1), in Arabidopsis. SnRK1, together with Target Of Rapamycin (TOR), is a kinase that is at the decision center that regulates growth, depending on the nutrient and energy status of the cell. Thus, OsCPK17 may be working upstream of SnRK1 (or TOR) to regulate rice growth, upon stress, or, instead be at the beginning of a new pathway that is itself a major negative regulator of rice growth. This also immediately poses the questions: (i) Does all CPK family target central metabolism besides their putative specific target proteins?, moreover, (ii) Is CPK-mediated effect on metabolism stress-specific or a general process of stress response?.

Growth-Stress NET will use state-of-the-art mass spectrometry methodologies, previously implemented by its team, to identify and quantify in vivo targets of rice kinases. Moreover, combine this approach with biochemical and molecular biology approaches to study the functional relevance of those findings. On Task 1, Growth-Stress NET will address the interplay between OsCPK17-dependent cold signaling and the major hubs that regulate growth. On Task 2, it will determine and compare which proteins are phosphorylated by OsCPK17 and OsCPK4, under salt stress and blast disease. On Task 4, it will address the functional effects of the phosphorylation of OsSPS4, OsSPS5, and OsNR1. Finally, on Task 3, it will integrate all information and build the signaling networks.

Two teams at ITQB and one at CRAG with complementary expertise and track record in the study of stress signaling networks and PTMs will come together for this project and will benefit from two specialists in SnRK1 as consultants.

Growth-Stress NET aims to contribute to the creation of a sustainable agricultural system that can respond to the growing demands for food and feed.