Executive Summary : | Catennella spp., a lesser known carrageenophyte red alga is dominantly associated with eco-sensitive sundarban mangrove ecosystem and unpublished data say, it is now found to exist in only vegetative form there while it is globally known to be alternating between bisexual gemetophytic (n) and tetrasporophytic (2n) isomorphic phases having a haplodiplontic life cycle. The carrageenan types are also known to vary among the life cycle phases with kappa and iota carrageenan being associated with gametophytic phase and lamda carrageenan being associated with tetrasporophytic phases. The key enzymes of carrageenan biosynthesis the galactose-6-sulfurylases and galactose-2,6-sulfurylases could be found to be preferentially expressed in gametophyte phase only leading to kappa/iota carrageenan synthesis, which is known to be a stronger gel forming carrageenan mostly used in food industry and known to provide mechanical defense from pathogens to the alga. Carrageenan biosynthesis is also reported to be highly influenced by the environmental factors like salinity, desiccation, pH, wave exposure, light intensity, photoperiod, turbidity, nutrients like nitrogen, phosphate, sulfate, depth of water, geographical locations, temperature, temporal factors like seasonal variations, that exist in a gradient in sundarban ecosystem. Under this background scenario, this proposal aims to exploit the ecological potential of this Catenella sp. from sundarban mangrove ecosystem as an environmental/climate change bioindicator and correlate its carrageenan biosynthesis with its haplodiplontic life phases across a changing environmental gradient. Especially the activity of the key enzyme galactose-6-sulfurylase and galactose-2,6-sulfurylase and its corresponding gene expression in this Catenella spp. could be the key determinant in controlling the carrageenan biosynthetic pathway across its environmental niche gradient and life cycle phases, thus being solely responsible for designating this alga as a potential bio-indicator of sundarban estuary. We want to hypothesize that with the help of predictive models designed out of the developed data from this project, the policy makers could trace the cryptic changes occurring in the estuarine environment during climate change. |