Characterization and Transposon Mutagenesis of the Maize (Zea mays) Pho1 Gene Family

Abstract

Phosphorus is an essential nutrient for all plants, but also one of the least mobile, and consequently least available, in the soil. Plants have evolved a series of molecular, metabolic and developmental adaptations to increase the acquisition of phosphorus and to maximize the efficiency of use within the plant. In Arabidopsis (Arabidopsis thaliana), the AtPHO1 protein regulates and facilitates the distribution of phosphorus within the plant. To investigate the role of PHO1 in maize (Zea mays), the B73 reference genome was searched for homologous sequences and four genes identified that were designated ZmPho1;1, ZmPho1;2a, ZmPho1;2b and ZmPho1;3. ZmPho1;2a and ZmPho1;2b are the most similar to AtPho1, and represent candidate co-orthologs that we hypothesize to have been retained following whole genome duplication. Tissue-and phosphate-specific differences in the accumulation of ZmPho1;2a and ZmPho1;2b transcripts were observed, indicating regulatory divergence. Furthermore, evidence was obtained for the phosphate-regulated production of anti-sense transcripts associated with both ZmPho1;2a and ZmPho1;2b, suggesting the possibility of regulatory crosstalk between paralogs. To characterize functional divergence between ZmPho1;2a and ZmPho1;2b, a program of transposon mutagenesis was initiated using the Ac/Ds system, and, here, we report the generation of novel alleles of ZmPho1;2a and ZmPho1;2b.