Genome-scale Screening, Characterization, and Expression Analysis of Sorghum bicolor Caffeoyl -Co-A Methyltransferase (CCoAOMT) Gene Family in Response to Drought and Salinity Stress

Sorghum bicolor is the world's fifth most popular cereal crop and staple grain for millions of people. It is cultivated predominantly for seeds, fodder, sugar, fibre and biomass. Lignin is an essential cell wall element found in most terrestrial plant species, offering rigidity. Emerging research reveals that the composition and extent of lignification in distinct plant tissues are responsible for stress tolerance to abiotic and biotic stressors. The enzyme Caffeoyl coenzyme-A O-methyltransferase (CCoAOMT) methylates caffeoyl-CoA resulting in the production of feruloyl-CoA, which is essential for the biosynthesis of both G and S lignin. CCoAOMT is the crucial enzyme, and its role in abiotic stress has not yet been explored in Sorghum. In the present study, the CCoAOMT gene family in Sorghum was comprehensively characterized in silico by examining its structural, functional, molecular and evolutionary characteristics and expression trends in response to drought and salinity stress. A total of 7 CCoAOMT gene members have been discovered in the Sorghum genome. These gene family members exhibited high sequence and syntenic conservation with Maize and Oryza. Transcription factor and promoter analysis of the SbCCoAOMT gene family revealed that these genes may play important roles in lignin biosynthesis, defence and various abiotic stress responses. Furthermore, in silico expression analysis and expression profiling by RT-qPCR displayed significant changes in SbCCoAOMT transcripts under drought and salinity stress conditions. This study will serve as a foundation for altering lignin biosynthesis to improve the abiotic stress tolerance of this economically and industrially important crop.