Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 10/27/2023
Publication Date: N/A
Technical Abstract: Spinach, a crucial horticultural crop, lacks comprehensive studies exploring genotypic responses to salinity, covering aspects like biomass yield, ion uptake, and genetic mechanisms of tolerance. To bridge this gap, we conducted a greenhouse experiment with 16 spinach genotypes, irrigated at Electrical Conductivity (EC) levels of 1.87 and 23.3 dS m-1. Our results highlighted significant variability in salt tolerance based on shoot biomass, enabling genotype ranking. Under high salinity, marked accumulations of Na+ and Cl- occurred in shoots and roots, with leaves showing 2.4 times more Na+ than roots. Genotypic variations in Na+ and Cl- partitioning between roots and leaves were evident, pointing to differences in ion extrusion and translocation mechanisms. Gene expression analyses shed light on processes like Na+/Cl- efflux, vacuolar sequestration, and ion homeostasis, essential for reactive oxygen species (ROS) scavenging. Furthermore, we explored the conservation of the Salt Overly Sensitive (SOS) pathway, a crucial regulator of intracellular sodium ion homeostasis in response to salt stress in plants, in spinach. The SOS pathway involves three primary genes, namely SOS1, SOS2, and SOS3, which belong to the Na+/H+ exchanger (NHX), CBL-interacting protein kinase (CIPK), and Calcineurin B-like (CBL) gene families, respectively. Through genome-wide identification and phylogenetic analyses of NHX, CIPK, and CBL genes in spinach, we identified single S. oleracea (So) SOS1, SOS2, and SOS3 proteins. The yeast two-hybrid assay revealed direct protein-protein interaction between SoSOS2 and SoSOS3 but not between SoSOS2 and SoSOS1. This finding suggests the possibility of unique modes of action for spinach SOS proteins compared to those in Arabidopsis. In conclusion, our study illustrates the conservation of SOS pathway genes in spinach, further enriching our understanding of the genetic basis of salinity tolerance in this crop.