Transcriptional control of cell fate in the stomatal lineage

Abstract

The Arabidopsis stomatal lineage is a microcosm of development; it undergoes selection of precursor cells, asymmetric and stem cell-like divisions, cell commitment and finally, acquisition of terminal cell fates. Recent transcriptomic approaches revealed major shifts in gene expression accompanying each fate transition, and mechanistic analysis of key bHLH transcription factors, along with mathematical modeling, has begun to unravel how these major shifts are coordinated. In addition, stomatal initiation is proving to be a tractable model for defining the genetic and epigenetic basis of stable cell identities and for understanding the integration of environmental responses into developmental programs.

On the mechanisms of development in monocot and eudicot leaves

“…Striking differences in stomatal patterning are noted in comparisons of monocot and eudicot leaves. Namely, stomata appear to be randomly distributed across the epidermis of eudicot leaves, whereas monocot stomata are arranged in evenly distributed, parallel rows (Han & Torii, 2016;Simmons & Bergmann, 2016;Hepworth et al, 2018). Genetic analyses in Arabidopsis have provided detailed, molecular genetic descriptions of the mechanisms of stomatal development (Han & Torii, 2016;Simmons & Bergmann, 2016).…”

“…Namely, stomata appear to be randomly distributed across the epidermis of eudicot leaves, whereas monocot stomata are arranged in evenly distributed, parallel rows (Han & Torii, 2016;Simmons & Bergmann, 2016;Hepworth et al, 2018). Genetic analyses in Arabidopsis have provided detailed, molecular genetic descriptions of the mechanisms of stomatal development (Han & Torii, 2016;Simmons & Bergmann, 2016). Comparative studies are shedding light on the shared and divergent mechanisms of angiosperm stomatal development, including new insights into stomatal patterning in monocots (Chater et al, 2011(Chater et al, , 2013Hepworth et al, 2018).…”

Reducing Stomatal Density in Barley Improves Drought Tolerance without Impacting on Yield

“…These cell fate transitions and divisions, which ultimately control the number and proportions of stomata and pavement cells in the mature leaf epidermis, are controlled by a subgroup of related basic helix-loop-helix (bHLH) transcription factors; SPCH, MUTE, and FAMA (Ohashi-Ito and Bergmann, 2006;MacAlister et al, 2007;Pillitteri and Torii, 2007). SPCH primarily directs expression of genes controlling meristemoid formation including members of the Cys-rich EPIDERMAL PATTERNING FACTOR (EPF) family of secreted signaling peptides, which in turn activate a pathway that regulates SPCH stability, thus forming a feedback loop that regulates the number of cells entering the stomatal lineage (Adrian et al, 2015;Simmons and Bergmann, 2016). The best characterized negative regulators of stomatal density in this peptide family are EPF1 and EPF2, which are numbered in order of their discovery (Hara et al, 2007(Hara et al, , 2009Hunt and Gray, 2009).…”

Origins and Evolution of Stomatal Development

“…Although we discuss the origins of stomatal function in the context of these new discoveries, the evolution of guard cell signaling and stomatal behavior has recently been reviewed (Assmann and Jegla, 2016;Chen et al, 2017;Xu et al, 2016). The complex cellular processes underpinning stomatal development, also the subject of several recent reviews (Torii, 2015;Han and Torii, 2016;Simmons and Bergmann, 2016), will be outlined briefly to provide the background to the evo-devo context.…”