title: Enhancement of carotenoids by mutation and stress induced carotenogenic genes in Haematococcus pluvialis mutants.
abstract: Growing culture of green alga Haematococcus was exposed to mutagens such as UV, ethyl methane sulphonate (EMS) and 1-methyl 3-nitro 1-nitrosoguanidine (NTG), and further screened over herbicide - glufosinate. The survival rate of cells decreased with increasing concentration of mutagens and herbicides. The mutants exhibited 23-59% increase in total carotenoid and astaxanthin contents. The NTG treated glufosinate resistant mutant showed increased (2.2% to 3.8% w/w) astaxanthin content. The transcript levels of phytoene synthase, phytoene desaturase, lycopene cyclase, beta-carotene ketolase and beta-carotene hydroxylase enzymes in the mutant cultures were found to be 13-18, 14-17, 3, 3-22 and 6-20 fold higher respectively compared to wild type. The mutant obtained by UV irradiation showed highest lycopene cyclase activity (458 nmole beta-carotene formed/mg protein/h) followed by NTG mutant (315 nmole beta-carotene formed/mg protein/h) when compared to that of parent strain (105 nmole beta-carotene formed/mg protein/h). Expression analysis of carotenoid biosynthetic genes in the mutants exhibited increase in transcript levels compared to wild type.
authors.affiliation: Plant Cell Biotechnology Department, Central Food Technological Research Institute, Mysore 570 020, India.
authors.forename: B
authors.initials: B
authors.lastname: Sandesh Kamath
authors.forename: R
authors.initials: R
authors.lastname: Vidhyavathi
authors.forename: R
authors.initials: R
authors.lastname: Sarada
authors.forename: G A
authors.initials: GA
authors.lastname: Ravishankar
mesh_terms: D018533:Biomass; D002338:Carotenoids / Q000096:biosynthesis / Q000235:genetics*; D002734:Chlorophyll / Q000378:metabolism; D000460:Chlorophyta / Q000187:drug effects / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D005020:Ethyl Methanesulfonate / Q000494:pharmacology; D005453:Fluorescence; D005786:Gene Expression Regulation / Q000187:drug effects / Q000528:radiation effects; D006540:Herbicides / Q000494:pharmacology; D019753:Intramolecular Lyases / Q000378:metabolism; D009154:Mutation / Q000235:genetics*; D009604:Nitrosoguanidines / Q000494:pharmacology; D010788:Photosynthesis / Q000187:drug effects / Q000528:radiation effects; D014466:Ultraviolet Rays; D024341:Xanthophylls / Q000096:biosynthesis
chemical_list: D006540:Herbicides; D009604:Nitrosoguanidines; D024341:Xanthophylls; D002734:Chlorophyll; D002338:Carotenoids; C005948:astaxanthine; D005020:Ethyl Methanesulfonate; D019753:Intramolecular Lyases; C070925:lycopene cyclase-isomerase