UC San Diego

Iron plays an essential role in the growth, development, and biological functions of all plants. Its importance extends from being involved in processes from photosynthesis and chlorophyll biosynthesis to plant growth and development. In environments where iron is present in low abundance, dicotyledonous plants such as Arabidopsis thaliana, have developed efficient strategies to acquire iron from the soil to overcome this. Some of these strategies include transcriptional changes, altering root structure architecture (RSA), and iron-translocation mechanisms to respond to environmental changes. As such, strict iron homeostasis must be maintained for proper growth and development. Vast networks of genes facilitate the proper response from environmental stimuli. These network of gene families encode for proteins with similar or overlapping functions. This feature is called gene redundancy and serves many purposes; mainly to confer robustness to biological functions to ensure that a single-gene mutation would not affect essential functions of the plant. However, this acts as an obstacle when trying to conduct a forward genetic screen. In this study, a mutant collection utilizing amiRNAs to combinatorially co-silence closely homologous gene clade members was used to circumvent this issue. AmiRNAs are single-stranded 21-mer RNAs whose sequence can target and silence multiple genes within the same family. From this collection, 12 candidate lines with observed unique primary root growth phenotypes under iron-deficient conditions, were selected and studied for further characterization. This will enable future studies to elucidate the mechanisms involved by associating the genes targeted in the candidate lines in connection to iron homeostasis.