Fungal infections result in millions of deaths and billions of superficial infections each year. Morphological transitions are critical for fungal virulence. Filamentous hyphal branching is affected by nutrients and suggested to be altered during infection. The aim of this interdisciplinary project is to determine the importance of branching in the human opportunistic fungal pathogen Candida albicans. Specifically, how is branching controlled and regulated in time/space during infection? Towards this goal, I will investigate branching at the molecular/cellular levels, and use genetic/molecular perturbation to delineate functions and requirements of branching. Live-cell imaging will be used to determine the frequency and position of hyphal branching, as a function of infection-relevant conditions, including growth on/in different stiffness substrates, physical confinement, nutrients and gaseous environment. This will help us to characterize the biophysics of branching and to understand the spatial regulation of the process. To address how branching is<br/>affected by host cells, this process will be followed in co-culture with reconstituted human epithelia To determine at molecular/cellular levels the critical processes and components that localize to incipient branch sites, I will use different fluorescent reporters. Targeted and unbiased, genetic/molecular approaches will be used to probe the functions and requirements of branching and selected mutants will be examined in mice. Using optogenetics, I will investigate perturbation of branching by induction of de novo branching. In summary, this interdisciplinary project, that takes advantage of cutting-edge imaging, molecular approaches and biophysics tools, will shed light on the importance and regulation of branching during fungal infections.