Multi-omics analysis reveals the positive impact of differential chloroplast activity during in vitro regeneration of barley.

Existence of potent in vitro regeneration system is a prerequisite for efficient genetic transformation and functional genomics of crop plants. In this study, two contrasting cultivars differencing in their in vitro regeneration efficiency were identified. Tissue culture friendly cultivar Golden Promise (GP) and tissue culture resistant DWRB91(D91) were selected as contrasting cultivars to investigate the molecular basis of regeneration efficiency through multiomics analysis. Transcriptomics analysis revealed 1487 differentially expressed genes (DEGs), in which 795 DEGs were upregulated and 692 DEGs were downregulated in the GP-D91 transcriptome. Genes encoding proteins localized in chloroplast and involved in ROS generation were upregulated in the embryogenic calli of GP. Moreover, proteome analysis by LC-MS/MS revealed 3062 protein groups and 16,989 peptide groups, out of these 1586 protein groups were differentially expressed proteins (DEPs). Eventually, GC-MS based metabolomics analysis revealed the higher activity of plastids and alterations in key metabolic processes such as sugar metabolism, fatty acid biosynthesis, and secondary metabolism. TEM analysis also revealed differential plastid development. Higher accumulation of sugars, amino acids and metabolites corresponding to lignin biosynthesis were observed in GP as compared to D91. A comprehensive examination of gene expression, protein profiling and metabolite patterns unveiled a significant increase in the genes encompassing various functions, such as ion homeostasis, chlorophyll metabolic process, ROS regulation, and the secondary metabolic pathway.