Arabidopsis, Mimulus, flower development; ovule and seed development, endosperm, gynoecium, transcriptional regulation, gene regulatory networks, molecular genetics, hybrid inviability
Arabidopsis Gynoecium Development – Reproductive competence of flowering plants requires proper development of the carpel, which is the female reproductive organ of the plant. The meristematic regions along the margin of the developing carpel generate ovules that will later develop into seeds. These meristematic regions have been termed carpel margin meristems (CMMs) and are functionally analogous to the mammalian ovary and placenta. The CMMs provide an excellent system to study basic problems in developmental biology such as patterning, the regulation of cellular proliferation and the control of organ size and shape. Dr. Franks’ research program seeks to clarify basic mechanisms of organ size and shape regulation and understand relationships between patterning cues and cellular proliferation within the carpel. Current research focuses on (1) the elucidation of the transcriptional gene regulatory network that controls ovule initiation and meristematic competence in the carpel; 2) the identification and functional studies of novel genes that play a critical role in CMM development; 3) the application of fluorescent activated cell sorting (FACS) technology to isolate transcriptionally-distinct populations of carpel cell types.
Hybrid Seed Inviability and the Evolution of Endosperm Development in Mimulus – The endosperm is the starch- and/or protein-rich tissue within the seed. It is estimated that 67% of the calories of the human diet are derived from the endosperm of agricultural varieties (mostly grains). In addition to its agricultural importance, the study of embryo and endosperm development is of interest to both developmental biologists and evolutionary biologists. The parental conflict theory is an evolutionary theory that predicts that genes supporting endosperm and embryo development will be subject to imprinting and parent-of-origin effects. Furthermore, the rapid evolution of genes that function in the regulation of parental conflict has been proposed to act as a reproductive isolation mechanism and thus may support speciation events. In this collaboration with Dr. John Willis in the Dept. of Biology at Duke University, we are examining embryo and endosperm developmental defects resulting from incompatible inter-specific crosses between Mimulus species. We expect these studies will illuminate developmental, molecular and evolutionary mechanisms of reproductive isolation and speciation, as well as mechanisms of endosperm development.
Selected Publications (link to complete list of publications; Google Scholar)
- Sehra, Bhupinder, and Robert G. Franks. (2017) “Redundant CArG Box Cis-Motif Activity Mediates SHATTERPROOF2 Transcriptional Regulation during Arabidopsis thaliana Gynoecium Development.” Frontiers in Plant Science 8 (October):1712.
- Ma, Qing, Xiang Liu, Robert G. Franks, and Qiu-Yun Jenny Xiang. (2017) “Alterations of CorTFL1 and CorAP1 Expression Correlate with Major Evolutionary Shifts of Inflorescence Architecture in Cornus (Cornaceae)–a Proposed Model for Variation of Closed Inflorescence Forms.” The New Phytologist 216 (2). 519–35.
- Villarino, Gonzalo H., Qiwen Hu, Silvia Manrique, Miguel Flores-Vergara, Bhupinder Sehra, Linda Robles, Javier Brumos, et al. (2016) “Transcriptomic Signature of the SHATTERPROOF2 Expression Domain Reveals the Meristematic Nature of Arabidopsis Gynoecial Medial Domain.” Plant Physiology 171 (1):42–61.
- Oneal, Elen, John H. Willis, and Robert G. Franks. (2016) “Disruption of Endosperm Development Is a Major Cause of Hybrid Seed Inviability between Mimulus Guttatus and Mimulus Nudatus.” The New Phytologist 210 (3):1107–20.
- Gong, Xue, Miguel A. Flores-Vergara, Jing Han Hong, Huangwei Chu, Jun Lim, Robert G. Franks, Zhongchi Liu, and Jian Xu. (2016) “SEUSS Integrates Gibberellin Signaling with Transcriptional Inputs from the SHR-SCR-SCL3 Module to Regulate Middle Cortex Formation in the Arabidopsis Root.” Plant Physiology 170 (3):1675–83.
- Ma, Qing, Xiang Liu, Robert G. Franks, and Qiu-Yun Jenny Xiang. (2016) “Alterations of CorTFL1 and CorAP1 Expression Correlate with Major Evolutionary Shifts of Inflorescence Architecture in Cornus (Cornaceae) – a Proposed Model for Variation of Closed Inflorescence Forms.” The New Phytologist, September. https://doi.org/10.1111/nph.14197.
- Sehra, B and Franks, R.G. (2015) Auxin and cytokinin act during gynoecial patterning and the development of ovules from the meristematic medial domain. WIREs Dev Bio. (2015) PMID:25951007.
- Wynn A.N., Seaman A. A., Jones A.L., Franks R.G. (2014) Novel functional roles for PERIANTHIA and SEUSS during floral organ identity specification, floral meristem termination and gynoecial development. Frontiers in Plant Science. Vol 5, No. 00130.
- Larsson, E., Roberts, C.J., Claes, A.R., Franks, R.G., Sundberg, E., 2014. Polar Auxin Transport is Essential for Medial versus Lateral Tissue Specification and Vascular-mediated Valve Outgrowth in Arabidopsis Gynoecia. Plant Physiol. 166, pp. 1998–2012
- Lee BH, Wynn AN, Franks RG, Hwang YS, Lim J, Kim JH. (2013). The Arabidopsis thaliana GRF-INTERACTING FACTOR gene family plays an essential role in control of male and female reproductive development. Dev Biol. Dec 16. pii: S0012-1606(13)00654-4
- Wynn, A.N., Rueschhoff, E.E. and Franks, R.G. (2011), Transcriptomic Characterization of a Synergistic Genetic Interaction during Carpel Margin Meristem Development in Arabidopsis thaliana. PLoS ONE 6(10): e26231. doi:10.1371/journal.pone.0026231
- Nole-Wilson, S., Rueschhoff, E.E., Bhatti, H., and Franks, R.G. (2010). Synergistic disruptions in seuss cyp85A2 double mutants reveal a role for brassinolide synthesis during gynoecium and ovule development. BMC Plant Biol 10, 198.
- Bao, F., Azhakanandam, S. and Franks, R.G. (2010) SEUSS and SEUSS-LIKE transcriptional adaptors regulate floral and embryonic development in Arabidopsis. Plant Physiology 152 (2) pp821-836.
- Azhakanandam, S., Nole-Wilson, S., Bao, F., and Franks, R.G. (2008). SEUSS and AINTEGUMENTA Mediate Patterning and Ovule Initiation during Gynoecium Medial Domain Development. Plant Physiology 146 (3) p1165-1181.
- Franks, R. G., Wang, C., Levin, J. Z., and Liu, Z. (2002) SEUSS, a Member of a Novel Family of Plant Regulatory Proteins, Represses Floral Homeotic Gene Expression with LEUNIG. Development (129, 253-263)
- Liu, Z., Franks, R. G. and Klink, V. P. (2000) Regulation of Gynoecium Marginal Tissue Formation by LEUNIG and AINTEGUMETA. Plant Cell 12: 1879-1891.