Fig 11. Model for Ros1 function in the control of late development of U. maydis.

The model shows the processes repressed (blue box) and induced (red box) by Ros1 during the late development of U. maydis. Ros1 inhibits filamentous growth of the dikaryon by downregulating elements of the bE/bW regulatory cascade. It also represses 128 effector genes (126 of the 320 predicted effector genes [47, 48] without functional domain, cmu1 [8] and UMAG_01130 [13]) (blue box). Concomitantly, Ros1 induces teliospore formation (Red box). Ros1 triggers karyogamy followed by proliferation of the diploid and matrix formation. This coincides with the upregulation of genes involved in cell cycle, DNA processing and protein synthesis. The gelatinization of the cell wall and subsequent fragmentation of sporogenous hyphae might involve cell wall loosening and membrane lipid synthesis. The two Ros1 induced transcription factors UMAG_02775 and UMAG_01390 regulate spore maturation following the fragmentation stage. Secondary metabolism, lipid storage as well as 70 late effectors are induced by Ros1. Yellow = cytoplasm, black line = cell wall, blue / red discs = nuclei, brown dots = matrix.