Molecular Characterization and Co-expression Analysis of the SnRK2 Gene Family in Sugarcane (Saccharum officinarum L.)

In plants, both abscisic acid (ABA) dependent and independent pathways form the basis for the response to environmental stresses. Sucrose non-fermenting 1-related protein kinase 2 (SnRK2) plays a central role in plant stress signal transduction. However, complete annotation and specific expression patterns of SnRK2s in sugarcane remain unclear. For the present study, we performed a full-length cDNA library survey of sugarcane, thus identifying ten SoSnRK2 genes via phylogenetic, local BLAST methods, and various bioinformatics analyses. Phylogenetic analysis indicated division of SoSnRK2 genes into three subgroups, similar to other plant species. Gene structure comparison with Arabidopsis suggested a unique evolutionary imprint of the SnRK2 gene family in sugarcane. Both sequence alignment and structural annotation provided an overview of the conserved N-terminal and variations of the C-terminal, suggesting functional divergence. Transcript and transient expression assays revealed SoSnRK2s to be involved in the responses to diverse stress signals, and strong ABA induction of SoSnRK2s in subgroup III. Co-expression network analyses indicated the existence of both conserved and variable biological functions among different SoSnRK2s members. In summary, this comprehensive analysis will facilitate further studies of the SoSnRK2 family and provide useful information for the functional validation of SoSnRK2s.