Maintenance and Function of the Barley Root Apical Meristem

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The stem cell niche (SCN) in the root apical meristem (RAM) provides the pool of stem cells necessary for the establishment and maintenance of the whole root system of a plant. Until now, most of the research on RAMs has been carried out in the eudicot model plant Arabidopsis thaliana. Here, it was shown that in addition to the phytohormones auxin and cytokinin, some of the key transcription factors (TFs) e.g., WUSCHEL RELATED HOMEOBOX 5, PLETHORA 1-4 and SHORTROOT and SCARECROW play important roles in RAM maintenance. In an intricate interplay these TFs regulate quiescent center positioning and divisions, which is crucial to a functional SCN and therefore also for a functional RAM. In monocot cereals like barley very little is known about the molecular factors controlling the necessary tight but also flexible regulation from stem cell fate to differentiation. Primary experiments suggest a more elaborate molecular regulation of the observed bigger stem cell pool in the SCN of the barley RAM generating also additional cell layers. Moreover, some predicted homologous molecular regulators are not expressed or in different cells indicating different functions in the barley RAM compared to Arabidopsis. To understand how the RAM of cereals is organized, maintained and how it functions, we aim to i) identify until now unknown molecular factors regulating the barley RAM as a cereal model and, in addition, ii) scrutinize the homologs of known molecular factors from Arabidopsis for their functional relevance in barley RAM maintenance.