Profiling of conserved orthologs and miRNAs for understanding their role in salt tolerance mechanism of Sesuvium portulacastrum L.

Abstract

Sesuvium portulacastrum is a facultative halophyte capable of thriving in a saline environment. Despite molecular studies conducted to unravel its salt adaptation mechanism, there is a paucity of information on the role of salt-responsive orthologs and microRNAs (miRNAs) in this halophyte. Here, we searched the orthology to identify salt-responsive orthologs and miRNA targets of Sesuvium using the Arabidopsis genome. The relative fold change of orthologs, conserved miRNAs, and miRNA targets of Sesuvium was analyzed under 100mM (LS) and 250mM NaCl (HS) treatment at 24h using qRT-PCR. The comparison between the expression of Sesuvium orthologs and Arabidopsis orthologs (Arabidopsis eFP browser database) was used to identify differentially expressed genes. Upon salt treatment, we found that SpCIPK3 (1.95-fold in LS and 2.90-fold in HS) in Sesuvium roots, and SpNHX7 (1.61-fold in LS and 6.39-fold in HS) and, SpSTPK2 (2.54-fold in LS and 7.65-fold in HS) in Sesuvium leaves were upregulated in a salt concentration-specific manner. In Arabidopsis, these genes were either downregulated or did not show significant variation, implicating its significance in the halophytic nature of Sesuvium. Furthermore, miRNAs like miR394a, miR396a, and miR397a exhibited a negative correlation with their targets-Frigida interacting protein 1, Cysteine proteinases superfamily protein, and Putative laccase, respectively under different salt treatments. The study revealed that the high salt tolerance in Sesuvium is associated with distinct transcriptional reprogramming, hence, to gain holistic mechanistic insights, global-scale profiling is required.