Shoot Meristem Maintenance And Immune Response Signaling Converge At The G Protein Beta Subunit

The shoot apical meristem (SAM) harbors a set of pluripotent stem cells that divide continuously to provide cells for the development of all aboveground plant parts (1). A concoction of hormonal and peptide signals and transcription factors, along with mechanical cues, play a role in stem cell maintenance, which requires a delicate balance between cell proliferation rates and rates of differentiation of stem cell daughters (1). The current challenge is to decipher how these signals come together to regulate stem cell maintenance, which requires the functional characterization of regulators in signaling pathways. The same regulators are often utilized for signaling in different contexts, such as development and disease, further complicating the analysis. The study by Wu et al. (2) reveals a role for the G protein β subunit (Gβ) in negatively regulating maize SAM size through the isolation of new alleles that uncouple its function in meristem development and disease resistance.\n\nThe critical SAM regulators were first characterized in Arabidopsis . A homeodomain transcription factor-WUSCHEL (WUS) is required for stem cell maintenance (3). WUS is expressed in the rib meristem (RM) located beneath the stem cells in the central zone (CZ) (4). WUS protein migrates into the overlying CZ where it regulates the expression of CLAVATA3 ( CLV3 ) through a unique concentration-dependent transcriptional switch (5). CLV3, a secreted … \n\n[↵][1]1To whom correspondence may be addressed. Email: venug{at}ucr.edu.\n\n [1]: #xref-corresp-1-1