Abstract
Cell division is often regulated by extracellular signaling networks to ensure correct patterning during development. In Arabidopsis, the SHORT-ROOT (SHR)/SCARECROW (SCR) transcription factor dimer activates CYCLIND6;1 (CYCD6;1) to drive formative divisions during root ground tissue development. Here, we show plasma-membrane-localized BARELY ANY MERISTEM1/2 (BAM1/2) family receptor kinases are required for SHR-dependent formative divisions and CYCD6;1 expression, but not SHR-dependent ground tissue specification. Root-enriched CLE ligands bind the BAM1 extracellular domain and are necessary and sufficient to activate SHR-mediated divisions and CYCD6;1 expression. Correspondingly, BAM-CLE signaling contributes to the restriction of formative divisions to the distal root region. Additionally, genetic analysis reveals that BAM-CLE and SHR converge to regulate additional cell divisions outside of the ground tissues. Our work identifies an extracellular signaling pathway regulating formative root divisions and provides a framework to explore this pathway in patterning and evolution.
Highlights
Cell division is often regulated by extracellular signaling networks to ensure correct patterning during development
Examination of 7-d-old bam1/2/3 triple and bam1/2 double mutant plants revealed a lack of formative divisions in presumptive cortex endodermal initial (CEI)/CEI daughter (CEID) cells resulting in the generation of a single ground tissue layer as in shr and scr mutants (Fig. 1 A and C and SI Appendix, Fig. S1 A and B), with bam1 single mutants displaying a quantitative delay in CEI divisions in 5-d-old seedlings (SI Appendix, Fig. S1A)
BARELY ANY MERISTEM1/2 (BAM1/2) are required for correct SHR-mediated CYCD6;1 expression and SHR is in turn required for ectopic CLE peptide-mediated formative divisions and CYCD6;1 expression
Summary
Cell division is often regulated by extracellular signaling networks to ensure correct patterning during development. In Arabidopsis, the SHORT-ROOT (SHR)/SCARECROW (SCR) transcription factor dimer activates CYCLIND6;1 (CYCD6;1) to drive formative divisions during root ground tissue development. We show plasmamembrane-localized BARELY ANY MERISTEM1/2 (BAM1/2) family receptor kinases are required for SHR-dependent formative divisions and CYCD6;1 expression, but not SHR-dependent ground tissue specification. BAM-CLE signaling contributes to the restriction of formative divisions to the distal root region. Genetic analysis reveals that BAM-CLE and SHR converge to regulate additional cell divisions outside of the ground tissues. Our work identifies an extracellular signaling pathway regulating formative root divisions and provides a framework to explore this pathway in patterning and evolution
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
