THE ROLE OF CLAVATA SIGNALING IN AUXIN-DEPENDENT INFLORESCENCE MERISTEM DEVELOPMENT

Plant development is highly tuned to environmental conditions such as light, daylength, and temperature. How these inputs are integrated into developmental programs to drive growth is a key question. During reproductive development, central zone stem cell proliferation in inflorescence meristems is negatively regulated by the CLAVATA3 (CLV3) signaling pathway. As these stem cells divide and enter the meristem flanks where the hormone auxin accumulates, cells proliferate to generate flower primordia. The CLAVATA2/CORYNE receptor complex promotes continuous flower outgrowth alongside CIK-family co-receptors in an auxin-dependent manner. I build upon that work to show that additional components of the CLV3 signaling pathway serve dual roles not only in meristem maintenance but also in flower primordia generation. These functions are separable and involve multiple CLV receptor classes, some repressed by the protein phosphatase POLTERGEIST. Additionally, there is a novel role for CLAVATA1 in auxin-dependent meristem maintenance which is more apparent in cooler temperatures where auxin levels are lower or in auxin biosynthetic mutant backgrounds. In higher temperatures or in the elf3 constitutive heat response mutant, we find these clv mutant defects to be suppressed. Interestingly, CLV signaling and auxin have synergistic effects at hot temperatures. In this way, I provide an updated mechanistic look at how the CLAVATA signaling pathway has opposing effects on cell proliferation across different meristem zones in addition to integrating environmental cues.