Mechanisms and manipulation of maize meristem size

The regulation of the size of meristems, groups of plant stem cells, plays an important role in plant development and crop productivity. Increases in meristem size achieved during the domestication of several crop species resulted in bigger fruits and inflorescences, and continue to offer great potential to increase yield. This proposal will provide a thorough understanding of the genetic and molecular mechanisms essential for increasing ear size in maize, a major crop worldwide, that can potentially translate to increased yields in commercial hybrids. The research will be integrated with active scientific training of high school students, and with a new research-based teaching module that combines classic genetic analysis with translational research tailored to graduate students. 

At the heart of the regulatory network controlling meristem size is the transcription factor WUSCHEL (WUS). WUSCHEL function has been proposed to have diversified between monocot and eudicot species. In maize, however, WUS function has yet to be explored, despite its importance in plant development and its recent use in plant transformation technologies. The proposed research will reveal the function of duplicated WUS genes in maize and their role as transcriptional repressors by combining genetic analysis and transgenic approaches with single cell transcriptomics of maize inflorescences. This work aims to uncover key mechanistic details of meristem size regulation in maize and monocots in general, answering long-standing questions regarding evolutionary conservation or diversification of WUS function, and to reveal new regulatory targets that could be genetically manipulated to increase maize yield and improve transformation efficiency.