Using decreased growth and photosynthesis during iron stress to identify Chlamydomonas reinhardtii mutants

Abstract

Photosynthetic organisms serve as the base of nutrients and energy in a food web for an environment. An essential component for photosynthesis that can often be limited is iron. In order to determine and better understand what some of the genes involved in iron stress are, the model algae Chlamydomonas reinhardtii was used. Predicted mutants with genes relating to iron were ordered from Chlamydomonas Library Project. PCR was performed on five of the ordered mutants, FOX1, FTR, IRT1, IRT2, and ALAD and the resulting gel electrophoresis showed bands present which indicated that four of five are successful mutations, with the exception of ALAD. These mutants were used to create screens and growth curves and identify the concentration of iron to induce stress in order to form conditions to test randomly generated mutants. In these growth curves the mutants showed decreased growth and photosynthesis when compared the wild type. Iron was added back into some of the low iron groups, and the absorbances increased, but not as much as the wild type. Using known mutants to generate conditions would mean randomly generated mutants that have mutations related to iron stress could be found, and from the screen ALAD was found to be an unknown mutant that did not recover from iron stress. Once found, ALAD was sequenced to identify the mutated gene. Not every gene has been characterized, so there is a possibility that a novel gene relating to iron stress is discovered. Any gene found could provide more insight into its function, not just in Chlamydomonas, but possibly in other photosynthetic organisms as well.