Importance of inositols and their derivatives in cowpea under root dehydration: An omics perspective.

Abstract

This work presents a robust analysis of the inositols (INSs) and raffinose family oligosaccharides (RFOs) pathways, using genomic and transcriptomic tools in cowpea under root dehydration. Nineteen (~70%) of the 26 scrutinized enzymes presented transcriptional up-regulation in at least one treatment time. The transcriptional orchestration allowed categorization of the analyzed enzymes as time-independent (those showing the same regulation throughout the assay) and time-dependent (those showing different transcriptional regulation over time). It is suggested that up-regulated time-independent enzymes (INSs: myo-inositol oxygenase, inositol-tetrakisphosphate 1-kinase 3, phosphatidylinositol 4-phosphate 5-kinase 4-like, 1-phosphatidylinositol-3-phosphate 5-kinase, phosphoinositide phospholipase C, and non-specific phospholipase C; RFOs: α-galactosidase, invertase, and raffinose synthase) actively participate in the reorganization of cowpea molecular physiology under the applied stress. In turn, time-dependent enzymes, especially those up-regulated in some of the treatment times (INSs: inositol-pentakisphosphate 2-kinase, phosphatidylinositol 4-kinase, phosphatidylinositol synthase, multiple inositol polyphosphate phosphatase 1, methylmalonate-semialdehyde dehydrogenase, triosephosphate isomerase, myo-inositol-3-phosphate synthase, phosphatidylinositol 3,4,5-trisphosphate 3-phosphatase and protein-tyrosine-phosphatase, and phosphatidylinositol 3-kinase; RFOs: galactinol synthase) seem to participate in fine-tuning of the molecular physiology, helping the cowpea plants to acclimatize under dehydration stress. Not all loci encoding the studied enzymes were expressed during the assay; most of the expressed ones exhibited a variable transcriptional profile in the different treatment times. Genes of the INSs and RFOs pathways showed high orthology with analyzed Phaseoleae members, suggesting a relevant role within this legume group. Regarding the promoter regions of INSs and RFOs genes, some bona fide cis-regulatory elements were identified in association with seven transcription factor families (AP2-EFR, Dof-type, MADS-box, bZIP, CPP, ZF-HD, and GATA-type). Members of INSs and RFOs pathways potentially participate in other processes regulated by these proteins in cowpea.