Coconut is a highly recalcitrant species with respect to tissue culture. The present study was carried out to compare the culture response from shoot meristem explants and gene expression patterns during various in vitro developmental stages in two cultivars of coconut viz. WCT (West Coast Tall) and COD (Chowghat Orange Dwarf) using RT-qPCR. Calli were obtained from shoot meristem explants and expression patterns of eight genes at different development stages in the two cultivars were analyzed using qRT-PCR. The results revealed enhanced expression of PKL, SERK and WUS was enhanced 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 compared to COD. Embryogenic calli of WCT showed higher expression of SERK, PKL and WUS compared to COD. Somatic embryos of COD showed high expression of GLP and GST compared to WCT, where as in case of ECP gene, higher expression was observed in WCT compared to COD. In case of WRKY and LEC, higher levels of expression were observed in meristemoids of WCT 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. These genes could therefore be useful as markers for somatic embryogenesis in coconut.
Key words: Coconut, recalcitrance, somatic embryogenesis, gene expression
|
