Practice question

In wild-type root meristem, cortex/endodermis initial stemming from stem cell niche undergoes formative asymmetric periclinal division producing distinct cortex and endodermis layers strictly controlled by SHR-SCR regulatory module. SCARECROW is essential to promote that division and to impose endodermal fate while repressing cortical program through downstream transcriptional activation. scr mutants fail to execute periclinal division, resulting single ground tissue layer surrounding stele. Molecular profiling reveals this solitary layer co-expresses cortical marker Co2 alongside endodermal markers CASP1 and ectopic lignin, indicating mixed identity and demonstrating necessity of SCR for both division and fate separation.