Influences of auxin on maize root morphogenesis

Research Summary:

Auxin signaling is a key regulator of root morphogenesis in angiosperms, yet this pathway is understudied in maize. Recent reports have demonstrated that root architecture can directly impact yield and drought resistance in maize, thus motivating the need to discover genetic factors that determine maize root architecture. We have discovered novel genetic drivers of maize root architecture using reverse genetics and quantitative genetics approaches. Based on maize co-expression gene regulatory networks and genetic analyses we have discovered that the Auxin Response Factor 27 (ARF27) is required for early root development and proper auxin-responsive gene expression. In addition, we have uncovered that two auxin efflux carriers, PIN-LIKES 2 (PILS2) and PILS6, are required for normal auxin transport in primary roots and may contribute to asymmetric auxin distributions across root zones. In the absence of PILS2 or PILS6 primary root growth is reduced and crown root formation is diminished. Genome-wide quantification for the levels of transcripts, proteins, and protein phosphorylation in primary roots following auxin treatment by RNA-sequencing and peptide mass spectrometry across several genotypes has enabled predictive gene regulatory network reconstruction. Finally, using the Wisconsin Diversity panel we have phenotyped young seedlings grown with and without exogenous auxin to perform genome wide association studies (GWAS) for several auxin-dependent traits. Our GWAS resulted in >60 high confidence candidate genes that may be linked to auxin dependent seedling growth, including ARF27 and PILS6. These studies expand our genetic repertoire of maize root growth factors and provide predictive molecular networks for future exploration.

About the Speaker:
Dior Kelley is a plant developmental geneticist studying the hormonal regulation of plant morphogenesis in Arabidopsis thaliana and Zea mays. She studied patterning and polarity in Arabidopsis ovule development during her PhD research at University of California, Davis. As postdoctoral fellow at UC San Diego she characterized tissue-specific auxin regulated proteome dynamics. Her research team at Iowa State University in Ames, IA focuses on identifying novel genes that influence root growth and development downstream of auxin signaling using functional genomics, reverse genetics, and predictive network approaches.

See the Kelley Lab website here

Contact

Sally Assmann
sma3@psu.edu