Abstract

1. Auxin Evo-Devo: Genetic and Genomic Approaches to Understanding the Role of Auxin in Shoot Development Jacob R. Withee1, Paula C. McSteen1, Simon T. Malcomber2, Andrea Gallavotti3, Yunde Zhao4, Naomi Altman5, RekaAlbert6 1 Division of Biological Sciences, University of Missouri. Columbia, MO 65211. 2 Department of Biological Sciences, California State University. Long Beach, CA, 90840. 3 The Waksman Institute of Microbiology, Rutgers University. Piscataway, NJ 08854. 4 Section of Cell and Developmental Biology, University of California, San Diego. La Jolla, CA 92093. 5 Department of Statistics, The Pennsylvania State University. University Park, PA 16802. 6 Department of Physics, The Pennsylvania State University. University Park, PA 16802. Abstract Functional genomics of maize barren mutants Auxin regulates nearly every aspect of plant growth and development. A better understanding of auxin’s function is therefore fundamentally important to basic plant biology and crop improvement. Previous research has demonstrated both conservation and diversification of auxin’s role in maize and Arabidopsis. This project will further our understanding of how auxin regulates shoot development, emphasizing maize shoot organogenesis. To identify additional genes functioning in auxin-mediated organogenesis, we are characterizing 147 maize mutants with distinctive vegetative and reproductive developmental defects. Together with previously characterized mutants, we have mapped 71 mutants to 40 locations in the maize genome. Eight of these loci had been cloned previously, and an additional six genes have been cloned on this project. Many of these genes encode proteins required for auxin biosynthesis, transport, and response. Preliminary phylogenetic analyses of 15 gene families have illustrated complex relationships amongst monocot and eudicot clades. Reverse genetic efforts guided by these phylogenetic relationships have confirmed 18 insertions in 12 genes. Further phylogenetic, functional and comparative expression analyses will test the conservation and diversification of auxin action mechanisms in all flowering plants. bif* Bif3 bif* bif* tls2 ub* Dvd1 ba2 Ba-ub* bl* baf1 rte1 ba* rel2 tls6 ba2 te1 dw* bif2 bl* Bif1 bl* br-ub tls5 smp* vt2 tls1 bl* tls7 lg2 Bif4 Baub* an1 bif* ba1 vt* br* Auxin is essential for shoot development smp* kn1 spi1 tls4 tls3 bif* blast 1 2 3 4 5 6 7 8 9 10 Map location of 40 barren* mutants in maize (blue have been cloned, dark blue cloned on this project) • Genetic analysis of 147 EMS-induced barren mutants (in progress) • Mapped mutants using SequenomMassArray SNP detection (71 completed, 22 in progress) • Allelism test and sequence (in progress, 15 confirmed or cloned) • Map-based cloning of 10-15 mutants (6 cloned, 12 in progress) tls3 br-ub* Mutants being cloned vanishing tassel 2 (vt2) phylogeny and gene expression patterns Arabidopsis Maize Mutants with a pin phenotype in Arabidopsis and a barren phenotype in maize ZmTAR1 dup ZmTAR1 OsTAR1 OsTAR2 vt2 dup vt2 TAR2 TAR1 TAA1 Reverse genetics: Confirmed Mu insertions OsTAR3 OsTAR4 ZmTAR3 ZmTAR4 TAR3 TAR4 • Relative, qualitative gene expression for maize vt2 gene family determined from in silico analysis • The vt2 and TAA1 clades are broadly expressed • Duplicate genes are expressed at a lower level • ZmTAR1/OsTAR1clade is endosperm and seed specific Highly expressed Not expressed Acknowledgements AUX/IAA ARF1 NPY vt2 spi1 bif2 PIN We thank Gerry Neuffer and the Maize Inflorescence Project for generating the mutants, the Maize Coop for providing the seed, Lu Gao, Mitzi Wilkening and Pat Schnable at Iowa State University for Sequenom analysis. This research was supported by the National Science Foundation grant number IOS 0820729/1114484. Auxin Signal Transduction Auxin Biosynthesis Auxin Transport