The Genetic Regulation of Tillering in Panicoid Grasses

Tillers are vegetative branches that grow at or near ground level in grasses, and largely determine grass biomass and grain yield. Tillering is a very plastic trait, affected by a multitude of different internal and external factors.  While several tillering genes have been identified in recent years in grasses such as maize and sorghum, it is unclear how these genes interact, whether they are part of a single pathway, how their expression is modulated by environmental inputs, and what other genes are involved.  To address these issues we are using three sequenced model panicoid C4 cereal crops, maize, sorghum and Setaria italica, which exhibit extreme reduction in tillering, together with their three progenitor wild species, which branch profusely.  Areas of investigation include 1) the use of forward genetics and chromatin immunoprecipitation to identify additional genes in the tb1/gt1 tillering pathway in maize, 2) the identification of candidate genes for tillering QTL in Setaria and sorghum, 3) high throughput sequencing of the tiller transcriptome and expression QTL in Setaria to build a tillering network in maize, sorghum, and Setaria for comparative analysis, 4) the development of reverse genetic tools in Setaria, and 5) the application of these results to modify tillering and improve agronomic traits in orphan African grain crops such as Tef (Eragrostis tef).  Our project also provides pre-service and in-service science teachers with research and professional development to support innovative science learning experiences that take research experiences into classroom practice.