Postdoctoral fellow UNC-Chapel Hill Carrboro, North Carolina
Body of Abstract: Rice provides 30% of the calories consumed by humans globally. Increasing rice robustness and yield (number of grains) will help satisfy the food needs of an ever-growing population, especially if climate change-imposed losses in yield can be mitigated. Altered sensitivity to the phytohormone cytokinin directly impacts rice yield. Cytokinin abundance in the panicle (inflorescence) increases grain production, though the exact regulation of this phenomenon remains unclear. Using CRISPR/Cas9, we developed an extensive collection of rice lines altered in cytokinin sensitivity and have characterized morphology in all but those for the type-A Response Regulators (RRs). The type-A RRs are negative regulators of cytokinin; therefore, disruption of these genes should increase yield in rice. Here, we demonstrate that loss of type-A RR function in rice alters key traits including grain yield and size, panicle architecture, and fitness. Further, we show that the sub-clades within the type-A RR gene family in rice can be attributed to difference functions and/or organs, as not all appear to be involved in panicle architecture. The outcomes of this work contribute to our understanding of the molecular regulation of yield in cereal crops, and likely the production of high-yield rice.