Comparative gene expression profiling during in vitro regeneration in two coconut cultivars

A comparative study of gene expression patterns during different stages of in vitro regeneration in two coconut cultivars viz. WCT (West Coast Tall) and COD (Chowghat Orange Dwarf) was carried out in this study. Calli were obtained from shoot meristem explants and expression patterns of eight genes at different development stages in the two cultivars were analyzed using RT-qPCR. The results revealed the enhanced expression of PKL, SERK and WUS in embryogenic calli compared to non-embryogenic calli. High expression of GLP, ECP and GST could be observed in normal somatic embryos compared to abnormal somatic embryos. Enhanced expression of ECP, LEAFY, GLP and WRKY could be observed in normal meristemoids compared to aberrant meristemoids. When the two cultivars were compared, higher somatic embryogenesis was noticed in WCT as compared to COD. Embryogenic calli of WCT showed higher expression of SERK, PKL and WUS compared to COD. Somatic embryos of WCT showed high expression of GLP and GST compared to COD, where as for ECP gene, higher expression was observed in WCT compared to COD. In cases of WRKY and LEC, higher levels of expression were observed in WCT meristemoids when compared to COD. The results revealed significant differences in regeneration potential and gene expression patterns in the two coconut cultivars suggesting genotypic differences of cultivars to in vitro culture.