Salt Stress Tolerance in Casuarina glauca: Insights from the Branchlets Transcriptome

Abstract

Climate change and the accelerated rate of population growth are imposing a progressive degradation of natural ecosystems worldwide. In this context, the use of pioneer trees represents a powerful approach to reverse the situation. Among others, N2-fixing actinorhizal trees constitute important elements of plant communities and have been successfully used in land reclamation at a global scale. In this study, we have analyzed the transcriptome of the photosynthetic organs of Casuarina glauca (branchlets) to unravel the molecular mechanisms underlying salt stress tolerance. For that, C. glauca plants supplied either with chemical nitrogen (KNO3+) or nodulated by Frankia (NOD+) were exposed to a gradient of salt concentrations (200, 400, and 600 mM NaCl) and RNA-Seq was performed. An average of ca. 25 million clean reads was obtained for each group of plants, corresponding to 86,202 unigenes. The patterns of differentially expressed genes (DEGs) clearly separate two groups: (i) control- and 200 mM NaCl-treated plants, and (ii) 400 and 600 mM NaCl-treated plants. Additionally, although the number of total transcripts was relatively high in both plant groups, the percentage of significant DEGs was very low, ranging from 6 (200 mM NaCl/NOD+) to 314 (600 mM NaCl/KNO3+), mostly involving down-regulation. The vast majority of up-regulated genes was related to regulatory processes, reinforcing the hypothesis that some ecotypes of C. glauca have a strong stress-responsive system with an extensive set of constitutive defense mechanisms, complemented by a tight mechanism of transcriptional and post-transcriptional regulation. The results suggest that the robustness of the stress response system in C. glauca is regulated by a limited number of genes that tightly regulate detoxification and protein/enzyme stability, highlighting the complexity of the molecular interactions leading to salinity tolerance in this species.

Transcriptome and metabolome analysis reveals key genes and secondary metabolites of Casuarina equisetifolia ssp. incana in response to drought stress

“…Many studies of plants have shown that ABA-and JAmediated signal transduction pathways are related to the response to drought stress [38][39][40]. It has been reported that the ABA and JA signaling pathways of C. equisetifolia and Casuarina glauca were activated under salt stress [41,42]. ABA that accumulates under drought stress can activate specific serine / threonine kinase family SnRK2, which can phosphorylate downstream transcription factors and activate ABA response genes [43,44].…”

Effect of Varied Salinity on Marigold Flowers: Reduced Size and Quantity Despite Enhanced Antioxidant Activity

“…In response to high salinity, salt-tolerant species elevate antioxidant levels to balance ROS, coordinating cellular processes such as water uptake and ion regulation [6,[9][10][11]. However, most plants are not tolerant to salinity, and a high degree of responses can even Agronomy 2023, 13, 3076 2 of 12 be found among sensitive and tolerant species.…”