UC San Diego

Yields in agriculturally important crops such as maize (Zea mays) depend on the normal growth of their flowering structures, making the understanding of inflorescence development a worthwhile undertaking. Through the analysis of ethyl methanesulfonate (EMS)-mutagenized maize populations, we identified a novel recessive mutant, rotten ear (rte), impaired in the development of inflorescences. Ears in rte mutants arrest during development and exhibit a brown or "rotten" appearance at the tip. In addition, the mutant plant is sterile and fails to develop fully fertile inflorescences. I mapped the rte mutant on chromosome 1, and successfully isolated the Rte gene through a map based cloning approach. Sequence and phylogenetic analyses showed that Rte is similar to the Arabidopsis thaliana BOR1 gene, suggesting that Rte may encode a boron transporter responsible for boron efflux. Although a notable phenotype was only detected in the inflorescences, the Rte gene is expressed in both vegetative and reproductive tissue, and in situ hybridizations show localized Rte expression around the vascular tissue. Moreover, transient expression assays in tobacco (Nicotiana benthamiana) cells show the RTE:YFP fusion protein sequestered to what appears to be the plasma membrane. Maize also has an Rte paralog, Rte-Like Rte-L), which was expressed in identical locations as Rte. Since the symptoms of boron deficiency are very diverse, it has been a challenge to determine the specific functions of boron in inflorescence and floral development. Because of this, we are investigating the role that the Rte gene plays during the development of maize inflorescences