Electronic Thesis and Dissertation Repository

Degree

Master of Science

Program

Biology

Supervisor

Dr. Yuhai Cui

Abstract

Seed germination is partially controlled by plant hormone gibberellins (GAs). Chemical mutagenesis yielded an Arabidopsis thaliana mutant gm11, which has an absolute gibberellin requirement for seed germination. This mutant exhibited phenotypes of GA-rescuable dwarfs, including dark-green leaves, and reduced fertility. However, with repeated GA treatment, gm11 develops into fertile plants with a nearly wild type phenotype. Bulked-segregant analysis mapped gm11 to the bottom arm of chromosome 1, and subsequent next-generation mapping revealed that the mutation is a G → A transition in At1g79460 (GA2), creating a premature stop codon. This gene encodes an ent-kaurene synthase (KS) which catalyzes the conversion of copalyl diphosphate to ent-kaurene in the GA biosynthesis pathway. Further genetic analysis suggests that gm11 is allelic to ga2 and has been named ga2-11. This work demonstrated a genetic finding useful for further understanding the molecular process underlying dormancy and germination.


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