Underlying molecular mechanisms triggered by the partial K replacement by Na in enhancing Eucalyptus drought tolerance

• Grant number: 24/07247-6
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: December 01, 2024
• End date: June 30, 2027
• Field of knowledge: Agronomical Sciences - Forestry Resources and Forestry Engineering - Forestry
• Principal Investigator: Paulo Mazzafera
• Grantee: Nikolas de Souza Mateus
• Host Institution: Instituto de Biologia (IB). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

Abstract

The partial replacement of potassium (K+), the most demanding nutrient for Eucalyptus, by sodium (Na+), a beneficial element, has been proposed as a promising management strategy to enhance forest productivity and alleviate drought impacts. However, the underlying molecular mechanisms triggering K+ and Na+-upregulated plant metabolism is a key challenge for the agricultural industry that have not been explored yet. We hypothesize that: (i) the partial replacement of K by Na enhances the expression of specific functional groups of transporters and aquaporins, which, in turn, upregulates ion and water transport systems, thereby and alleviating drought-induced stress; (ii) the Na¿ replaces for K¿ in activating K¿-dependent enzymes involved in C metabolism (Calvin cycle and glycolytic pathway) and N metabolism (such as NR, NiR, and GS/GOGAT cycle), with potential species-specific variations; (iii) alterations in the transcriptional regulation of specific enzyme genes lead to corresponding changes in their enzyme activities; (iv) partial replacement of K by Na may not cause drastic changes in the metabolome of plants. A pot experiment with two ratios of K/Na (K-supplied and partial K replacement by Na) and two water regimes, well-watered (W+) and water-stressed (W-), will be carried out on saplings of two Eucalyptus species with contrasting drought sensitivities. Together with leaf gas exchange parameters and leaf water content, we will evaluate the gene expression dynamics of specific aquaporins, transporters, and K¿-dependent enzymes involved in C and N metabolism, and measure the maximal activities of these key enzymes to validate the observed changes in gene expression. This research holds promise for promoting sustainable forestry practices and reducing dependence on expensive K+ fertilizers by increasing nutrient and water use efficiencies, contributing to both economic and environmental resilience in the face of increasing drought challenges. (AU)