Stomatal lineage progression and spacing (EPF-ERECTA-YODA-MAPK and SPCH/MUTE/FAMA-SCRM)

In the Arabidopsis leaf epidermis, stomata are produced by a dedicated cell lineage whose successive transitions are driven by three closely related group Ia bHLH transcription factors, each acting as a heterodimer with the broadly expressed group IIIb bHLHs SCREAM/ICE1 (SCRM) and SCRM2. SPEECHLESS (SPCH) initiates the lineage by driving the asymmetric entry division of a meristemoid mother cell, MUTE terminates the self-renewing asymmetric divisions of the meristemoid and converts it into a guard mother cell (GMC), and FAMA drives the single symmetric GMC division and guard cell differentiation, then locks in guard cell fate with RETINOBLASTOMA-RELATED. Lineage entry and spacing are restrained by cell-cell signalling: the secreted cysteine-rich peptide EPF2, produced by early lineage cells, binds the leucine-rich-repeat receptor kinase ERECTA in a complex with the non-catalytic co-receptor TOO MANY MOUTHS (TMM); ligand binding recruits SERK co-receptor kinases and activates the MAPKKK YODA, which phosphorylates MKK4/MKK5, which in turn activate MPK3/MPK6. MPK3/MPK6, docked onto SCRM through its KiDoK motif and recruited with YODA to the cortex by the polarity scaffold BASL, phosphorylate SPCH and SCRM and promote their degradation, limiting lineage entry. Because SPCH-SCRM directly activates EPF2 and TMM, the circuit forms a negative feedback loop that self-organizes stomatal density and the one-cell spacing rule. The related peptide EPF1, perceived mainly by ERL1, acts later on spacing divisions, and the positive peptide stomagen (EPFL9) competes with EPF2 for ERECTA-TMM. Brassinosteroid (via BIN2 inhibition of YODA), CO2 (via CRSP cleavage of EPF2) and other environmental inputs converge on this module.

MODULE:stomatal_lineage_developmentDRAFTCONCRETEDevelopmental Processmodules/stomatal_lineage_development.yaml

stomatal complex developmentGO:0010374 stomatal lineage progressionGO:0010440 stomatal complex patterningGO:0010375

PMID:18641265

SCREAM/ICE1 and SCREAM2 specify three cell-state transitional steps leading to arabidopsis stomatal differentiation.

SPCH, MUTE and FAMA act as heterodimers with SCRM/ICE1 and SCRM2 at three successive steps.

Here, we identify two paralogous proteins, SCREAM (SCRM) and SCRM2, which directly interact with and specify the sequential actions of SPCH, MUTE, and FAMA.

PMID:17183267

Termination of asymmetric cell division and differentiation of stomata.

SPCH, MUTE and FAMA control stomatal development at three consecutive steps.

Together, SPCH, MUTE and FAMA bHLH proteins control stomatal development at three consecutive steps

PMID:22241782

Direct interaction of ligand-receptor pairs specifying stomatal patterning.

ERECTA-family receptors are the primary EPF receptors; EPF2-ERECTA specifies lineage entry and TMM modulates the signal.

Our results place the ERECTA family as the primary receptors for EPFs with TMM as a signal modulator and establish EPF2-ERECTA and EPF1-ERL1 as ligand-receptor pairs specifying two steps of stomatal development

PMID:17259259

Stomatal development and patterning are regulated by environmentally responsive mitogen-activated protein kinases in Arabidopsis.

MKK4/MKK5-MPK3/MPK6 act downstream of YODA in stomatal development.

We further establish that the MKK4/MKK5-MPK3/MPK6 module is downstream of YODA, a MAPKKK.

PMID:26203655

Molecular Framework of a Regulatory Circuit Initiating Two-Dimensional Spatial Patterning of Stomatal Lineage.

SPCH-SCRM directly activates EPF2 and TMM, closing a negative feedback loop.

This transcription factor module directly binds to the promoters and activates a secreted signal, EPIDERMAL PATTERNING FACTOR2, and the receptor modifier TOO MANY MOUTHS, while the receptor ERECTA lies outside of this module.

Boundary: the module covers the core EPF2-ERECTA/TMM-YODA-MKK4/5-MPK3/6 inhibitory relay and the SPCH-MUTE-FAMA/SCRM transcriptional switch of the Arabidopsis stomatal lineage. Parallel or modulatory components are described in prose but not modelled as annotons because they lack gene reviews in this repository: EPF1 and ERL1/ERL2 (spacing divisions), stomagen/EPFL9 (antagonist ligand), SERK co-receptors, BASL/POLAR polarity scaffolds, BIN2, CRSP, SCRM2 and MPK3 (MPK3 is named in prose as MPK6's redundant partner). MKK4 and MKK5 are grounded as representative members of the redundant MAPKK step and both have complete gene reviews. Annoton molecular functions follow the gene reviews' core_functions (EPF2, TMM, ERECTA, YDA, MKK4, MKK5, MPK6, SPCH, MUTE, FAMA, ICE1). No production GO-CAM in gocams/index.tsv contains any member, so no gocam_associations are given. No PANTHER family ids are asserted (families are described by preferred_term and representative members only). Deep research by the Falcon provider was unavailable (HTTP 402) during this session.

11Nodes

10Parts

0Variant Sets

0Variants

10Annotons

8Connections

Derived QC

Recommended-field compliance

100.0% recommended fields populated

All recommended fields populated.

Module deep research

✗ none found

No MODULE:stomatal_lineage_development deep-research report alongside the module YAML.

Leaf nodes lacking representative members

✓ every leaf node grounds to a representative protein.

Template conformance

✓ every declared conforms_to bundle matches its template motif.

Function consistency and core coverage

11 gene-function check(s) reflected in core functions · 0 conflict(s) · 1 evidence or coverage gap(s) (12 comparison(s))

Retained noncore functions are reported separately; they do not require promotion to core functions. Support from representative genes does not establish conservation across the whole family. Missing reviews or identifiers leave a claim unverified.

Annoton	Participant	Function	Assessment
epf2_ligand	EPF2 UniProtKB:Q8LC53 Gene	receptor ligand activity GO:0048018	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
erecta_receptor	ERECTA UniProtKB:Q42371 Gene	transmembrane receptor protein serine/threonine kinase activity GO:0004675	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
tmm_coreceptor	TMM UniProtKB:Q9SSD1 Gene	coreceptor activity GO:0015026	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
yda_mapkkk	YDA (YODA) UniProtKB:Q9CAD5 Gene	MAP kinase kinase kinase activity GO:0004709	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
mkk4_mkk5_activity	MKK4 UniProtKB:O80397 Family Representative	MAP kinase kinase activity GO:0004708	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
mkk4_mkk5_activity	MKK5 UniProtKB:Q8RXG3 Family Representative	MAP kinase kinase activity GO:0004708	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
mpk6_mapk	MPK6 UniProtKB:Q39026 Gene	MAP kinase activity GO:0004707	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
ice1_partner	ICE1 (SCRM) UniProtKB:Q9LSE2 Gene	protein heterodimerization activity GO:0046982	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
spch_tf	SPCH UniProtKB:Q700C7 Gene	DNA-binding transcription activator activity GO:0001216	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
mute_tf	MUTE UniProtKB:Q9M8K6 Gene	DNA-binding transcription factor activity GO:0003700	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
fama_tf	FAMA UniProtKB:Q56YJ8 Gene	DNA-binding transcription factor activity GO:0003700	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
mkk4_mkk5_activity	MKK4/MKK5 group C MAP kinase kinases Family	MAP kinase kinase activity GO:0004708	Family Id Missing The family has no identifier linking it to a curated family review.

Feedback loops (advisory, prose-driven: a regulator counts as "feedback" when its own description says so)

✓ every negative regulator described as feedback has an upstream edge closing the loop.

yoda_mapk_cascade ⊣ spch_entry [closed]
yoda_mapk_cascade is regulated by epf2_erecta_tmm_perception: feedback loop closed

Gene-review completeness (11/11 grounded genes reviewed)

10 complete review(s) · 5 with deep research · 0 missing review · 6 reviewed but lacking deep research

Gene	Review	Complete	Deep research
EPF2 Q8LC53	✓	✓	✗
ERECTA Q42371	✓	✓	✗
FAMA Q56YJ8	✓	✓	✗
ICE1 Q9LSE2	✓	✓	✗
MKK4 O80397	✓	40/41	✓
MKK5 Q8RXG3	✓	✓	✓
MPK6 Q39026	✓	✓	✓
MUTE Q9M8K6	✓	✓	✓
SPCH Q700C7	✓	✓	✓
TMM Q9SSD1	✓	✓	✗
YDA Q9CAD5	✓	✓	✗

Tree

Stomatal lineage progression and spacingDevelopmental Processstomatal_lineage_development

Parts
1. 1. peptide ligand perception at the cell surface
2. EPF2 perception by the ERECTA-TMM receptor complexRegulatory Stepepf2_erecta_tmm_perception
  
  Annotons
  - EPF2: inhibitory peptide ligand Gene Product: EPF2
  - ERECTA: LRR receptor kinase Gene Product: ERECTA
  - TMM: non-catalytic LRR co-receptor Gene Product: TMM
3. 2. MAP kinase relay
4. YODA-MKK4/5-MPK3/6 MAP kinase cascadeSignaling Pathwayyoda_mapk_cascade
  
  Parts
  1. 1. MAPKKK
  2. YODA MAP kinase kinase kinaseRegulatory Stepyoda_mapkkk
    
    Annotons
    
    YDA: MAP kinase kinase kinase Gene Product: YDA (YODA)
  3. 2. MAPKK
  4. MKK4/MKK5 MAP kinase kinasesRegulatory Stepmkk4_mkk5_mapkk
    
    Annotons
    
    MKK4/MKK5: MAP kinase kinase (redundant pair) Family: MKK4/MKK5 group C MAP kinase kinases
  5. 3. MAPK
  6. MPK3/MPK6 MAP kinasesRegulatory Stepmpk3_mpk6_mapk
    
    Annotons
    
    MPK6 (with MPK3): MAP kinase Gene Product: MPK6
5. 3. bHLH transcriptional switch of the stomatal lineage
6. SPCH, MUTE and FAMA heterodimers with SCRM/ICE1Regulatory Stepbhlh_lineage_switch
  
  Parts
  1. 1. shared heterodimer partner and MAPK scaffold
  2. SCRM/ICE1 common bHLH partnerRegulatory Stepscrm_partner
    
    Annotons
    
    ICE1/SCRM: heterodimer partner of SPCH, MUTE and FAMA Gene Product: ICE1 (SCRM)
  3. 2. lineage entry and asymmetric division
  4. SPCH-driven lineage entryRegulatory Stepspch_entry
    
    Annotons
    
    SPCH: lineage-initiating bHLH activator Gene Product: SPCH
  5. 3. meristemoid to guard mother cell transition
  6. MUTE-driven meristemoid-to-GMC transitionRegulatory Stepmute_transition
    
    Annotons
    
    MUTE: terminates meristemoid divisions Gene Product: MUTE
  7. 4. guard cell differentiation and fate commitment
  8. FAMA-driven guard cell differentiationRegulatory Stepfama_differentiation
    
    Annotons
    
    FAMA: terminal guard cell differentiation factor Gene Product: FAMA

Details

Context

Arabidopsis thalianaNCBITaxon:3702

extracellular regionGO:0005576 plasma membraneGO:0005886 cell cortexGO:0005938 nucleusGO:0005634

Stomatal lineage progression and spacingDevelopmental Processstomatal_lineage_development

EPF2 peptide signalling through ERECTA/TMM and the YODA-MKK4/5-MPK3/6 cascade restrains the SPCH-SCRM lineage-entry factor, while SPCH, MUTE and FAMA (each heterodimerized with SCRM) drive the successive stomatal lineage transitions.

stomatal complex developmentGO:0010374 stomatal lineage progressionGO:0010440 stomatal complex patterningGO:0010375

Context

Arabidopsis thalianaNCBITaxon:3702

extracellular regionGO:0005576 plasma membraneGO:0005886 cell cortexGO:0005938 nucleusGO:0005634

Connections

epf2_erecta_tmm_perception -> yoda_mapk_cascade Positively Regulates

EPF2 binding to ERECTA-TMM (with SERKs) activates the YODA-MKK4/5-MPK3/6 cascade.

PMID:26083750

Application of MEPF2 peptides to Arabidopsis wild-type seedlings rapidly elicited phosphorylation of MPK3 and MPK6 in 10 min, a characteristic signature of MAPK activation

yoda_mapk_cascade -> spch_entry Negatively Regulates

MPK3/MPK6, docked on SCRM, phosphorylate SPCH (and SCRM) and promote their degradation, limiting stomatal lineage entry.

PMID:25843888

Activated MPK3/6 reinforces the feedback loop by phosphorylating BASL and inhibits stomatal fate by phosphorylating SPCH.

spch_entry -> epf2_erecta_tmm_perception Positively Regulates

Negative feedback loop - SPCH-SCRM directly activates EPF2 and TMM transcription, so lineage entry generates the inhibitory signal for neighbouring cells.

PMID:26203655

This transcription factor module directly binds to the promoters and activates a secreted signal, EPIDERMAL PATTERNING FACTOR2, and the receptor modifier TOO MANY MOUTHS

Part 1: peptide ligand perception at the cell surface

EPF2 perception by the ERECTA-TMM receptor complexRegulatory Stepepf2_erecta_tmm_perception

Secreted EPF2 binds the ERECTA ectodomain in a constitutive complex with the co-receptor TMM, activating ERECTA kinase signalling.

Annotons

EPF2: inhibitory peptide ligand

epf2_ligand

Participant: Gene Product: EPF2

Gene Product:

EPF2UniProtKB:Q8LC53

Function

receptor ligand activityGO:0048018

Processes

negative regulation of stomatal complex developmentGO:2000122

Locations

extracellular regionGO:0005576

Produced by meristemoid mother cells and early lineage cells; inhibits neighbouring protodermal cells from adopting MMC fate.

PMID:26083750

EPF2 directly binds ERECTA and TMM and elicits rapid MPK3/6 phosphorylation.

Both EPF2 and Stomagen directly bind to ER and its co-receptor TOO MANY MOUTHS.

file:ARATH/EPF2/EPF2-ai-review.yaml

Gene review core function receptor ligand activity in negative regulation of stomatal complex development.

ERECTA: LRR receptor kinase

erecta_receptor

Participant: Gene Product: ERECTA

Gene Product:

ERECTAUniProtKB:Q42371

Function

transmembrane receptor protein serine/threonine kinase activityGO:0004675

Processes

negative regulation of stomatal complex developmentGO:2000122

Locations

plasma membraneGO:0005886

Principal EPF2 receptor; recruits SERK co-receptor kinases and relays the signal to YODA. Paralogs ERL1/ERL2 perceive EPF1 at later spacing divisions.

PMID:26320950

EPF ligands induce ERECTA-SERK heteromerization and SERKs act upstream of the MAPK cascade.

SERK family RLKs regulate stomatal patterning downstream of EPF ligands and upstream of a MAP kinase cascade

file:ARATH/ERECTA/ERECTA-ai-review.yaml

Gene review core function.

TMM: non-catalytic LRR co-receptor

tmm_coreceptor

Participant: Gene Product: TMM

Gene Product:

TMMUniProtKB:Q9SSD1

Function

coreceptor activityGO:0015026

Processes

stomatal complex patterningGO:0010375

Locations

plasma membraneGO:0005886

Forms constitutive complexes with ERECTA/ERL1 that create the EPF1/EPF2 binding pocket and exclude EPFL4/6, acting as a ligand-specificity switch.

PMID:28536146

TMM-ERf complexes are the receptors of EPF1 and EPF2.

TMM interaction with ERL1 creates a binding pocket for recognition of EPF1 and EPF2, indicating that the constitutive TMM-ERf complexes function as the receptors of EPF1 and EPF2.

file:ARATH/TMM/TMM-ai-review.yaml

Gene review core function.

Part 2: MAP kinase relay

YODA-MKK4/5-MPK3/6 MAP kinase cascadeSignaling Pathwayyoda_mapk_cascade

The MAPKKK YODA activates the redundant MAPKKs MKK4/MKK5, which activate the redundant MAPKs MPK3/MPK6; BASL concentrates YODA and MPK3/6 at the cortex of asymmetrically dividing cells.

MAPK cascadeGO:0000165

Connections

yoda_mapkkk -> mkk4_mkk5_mapkk Positively Regulates

YODA phosphorylates and activates MKK4/MKK5.

PMID:17259259

We further establish that the MKK4/MKK5-MPK3/MPK6 module is downstream of YODA, a MAPKKK.

PMID:22307275

BIN2 phosphorylates YDA to inhibit YDA phosphorylation of its substrate MKK4

mkk4_mkk5_mapkk -> mpk3_mpk6_mapk Positively Regulates

MKK4/MKK5 phosphorylate and activate MPK3/MPK6.

PMID:17259259

We further establish that the MKK4/MKK5-MPK3/MPK6 module is downstream of YODA, a MAPKKK.

Part 1: MAPKKK

YODA MAP kinase kinase kinaseRegulatory Stepyoda_mapkkk

Annotons

YDA: MAP kinase kinase kinase

yda_mapkkk

Participant: Gene Product: YDA (YODA)

Gene Product:

YDA (YODA)UniProtKB:Q9CAD5

Function

MAP kinase kinase kinase activityGO:0004709

Processes

MAPK cascadeGO:0000165 negative regulation of stomatal complex developmentGO:2000122

Locations

cell cortexGO:0005938

PMID:15178800

YODA loss gives excess stomata; constitutive YODA eliminates stomata.

Null mutations in YODA lead to excess stomata, whereas constitutive activation of YODA eliminated stomata.

file:ARATH/YDA/YDA-ai-review.yaml

Gene review core function.

Part 2: MAPKK

MKK4/MKK5 MAP kinase kinasesRegulatory Stepmkk4_mkk5_mapkk

Annotons

MKK4/MKK5: MAP kinase kinase (redundant pair)

mkk4_mkk5_activity

Participant: Family: MKK4/MKK5 group C MAP kinase kinases

Family:

MKK4/MKK5 group C MAP kinase kinases

Representative Members: MKK4UniProtKB:O80397 MKK5UniProtKB:Q8RXG3

Function

MAP kinase kinase activityGO:0004708

Processes

MAPK cascadeGO:0000165 negative regulation of stomatal complex developmentGO:2000122

Phosphorylated by YODA; activate MPK3/MPK6. Loss of MKK4/MKK5 causes stomatal clustering.

PMID:17259259

MKK4/MKK5 and MPK3/MPK6 regulate stomatal development downstream of YODA.

Loss of function of MKK4/MKK5 or MPK3/MPK6 disrupts the coordinated cell fate specification of stomata versus pavement cells, resulting in the formation of clustered stomata.

PMID:22307275

YDA phosphorylates MKK4.

BIN2 phosphorylates YDA to inhibit YDA phosphorylation of its substrate MKK4

Part 3: MAPK

MPK3/MPK6 MAP kinasesRegulatory Stepmpk3_mpk6_mapk

Annotons

MPK6 (with MPK3): MAP kinase

mpk6_mapk

Participant: Gene Product: MPK6

Gene Product:

MPK6UniProtKB:Q39026

Function

MAP kinase activityGO:0004707

Processes

MAPK cascadeGO:0000165

Locations

nucleusGO:0005634 cell cortexGO:0005938

Acts redundantly with MPK3 (UniProtKB:Q39023); phosphorylates SPCH and SCRM in the nucleus (docked on SCRM's KiDoK motif) and BASL at the cortex.

PMID:19008449

SPCH is a MAPK phosphorylation target.

We found that a unique domain in a basic helix-loop-helix (bHLH) stomatal initiating factor, SPEECHLESS, renders it a MAPK phosphorylation target in vitro and modulates its function in vivo.

file:ARATH/MPK6/MPK6-ai-review.yaml

Gene review core function MAP kinase activity.

Part 3: bHLH transcriptional switch of the stomatal lineage

SPCH, MUTE and FAMA heterodimers with SCRM/ICE1Regulatory Stepbhlh_lineage_switch

Stage-specific group Ia bHLHs heterodimerize with SCRM/ICE1 (or SCRM2) to drive lineage entry (SPCH), meristemoid-to-GMC transition (MUTE) and guard cell differentiation (FAMA).

Connections

spch_entry -> mute_transition Precedes

SPCH-initiated meristemoids later express MUTE, which terminates their asymmetric divisions.

mute_transition -> fama_differentiation Precedes

MUTE-specified GMCs express FAMA, which drives the symmetric division and guard cell differentiation.

scrm_partner -> spch_entry Positively Regulates

SCRM/SCRM2 heterodimerize with SPCH (and likewise MUTE and FAMA) and are required for each transition.

PMID:18641265

successive loss of SCRM and SCRM2 recapitulated the phenotypes of fama, mute, and spch

Part 1: shared heterodimer partner and MAPK scaffold

SCRM/ICE1 common bHLH partnerRegulatory Stepscrm_partner

Annotons

ICE1/SCRM: heterodimer partner of SPCH, MUTE and FAMA

ice1_partner

Participant: Gene Product: ICE1 (SCRM)

Gene Product:

ICE1 (SCRM)UniProtKB:Q9LSE2

Function

protein heterodimerization activityGO:0046982

Processes

stomatal lineage progressionGO:0010440

Locations

nucleusGO:0005634

Redundant with SCRM2; also scaffolds MPK3/MPK6 to SPCH through its KiDoK motif (protein-macromolecule adaptor activity), coupling the MAPK cascade to lineage-entry control.

PMID:31235876

SCRM is a scaffold that recruits MPK3/6 to SPCH.

here, we report that the basic helix-loop-helix protein SCREAM functions as a scaffold that recruits MPK3/6 to downregulate SPEECHLESS, a transcription factor that initiates stomatal cell lineages.

file:ARATH/ICE1/ICE1-ai-review.yaml

Gene review core functions (heterodimerization, DNA-binding TF, adaptor).

Part 2: lineage entry and asymmetric division

SPCH-driven lineage entryRegulatory Stepspch_entry

Annotons

SPCH: lineage-initiating bHLH activator

spch_tf

Participant: Gene Product: SPCH

Gene Product:

SPCHUniProtKB:Q700C7

Function

DNA-binding transcription activator activityGO:0001216

Processes

regulation of stomatal complex developmentGO:2000038

Locations

nucleusGO:0005634

Initiates the stomatal lineage by directing the asymmetric entry division; directly activates EPF2, TMM and SCRM (feedback); phosphorylated and destabilized by MPK3/MPK6.

PMID:17183267

SPCH directs the first asymmetric division.

We show that SPCH directs the first asymmetric division that initiates stomatal lineage.

file:ARATH/SPCH/SPCH-ai-review.yaml

Gene review core function (read-only member for this module).

Part 3: meristemoid to guard mother cell transition

MUTE-driven meristemoid-to-GMC transitionRegulatory Stepmute_transition

Annotons

MUTE: terminates meristemoid divisions

mute_tf

Participant: Gene Product: MUTE

Gene Product:

MUTEUniProtKB:Q9M8K6

Function

DNA-binding transcription factor activityGO:0003700

Processes

stomatal complex developmentGO:0010374

Locations

nucleusGO:0005634

PMID:17183267

MUTE is the switch for meristemoid fate transition.

Here we report that the Arabidopsis thaliana basic helix-loop-helix (bHLH) protein MUTE is a key switch for meristemoid fate transition.

file:ARATH/MUTE/MUTE-ai-review.yaml

Gene review core function (read-only member for this module).

Part 4: guard cell differentiation and fate commitment

FAMA-driven guard cell differentiationRegulatory Stepfama_differentiation

Annotons

FAMA: terminal guard cell differentiation factor

fama_tf

Participant: Gene Product: FAMA

Gene Product:

FAMAUniProtKB:Q56YJ8

Function

DNA-binding transcription factor activityGO:0003700

Processes

guard cell differentiationGO:0010052

Locations

nucleusGO:0005634

Drives guard cell differentiation and halts GMC divisions; recruits RBR via an LxCxE motif to make guard cell fate irreversible.

PMID:17088607

FAMA promotes guard cell differentiation and halts precursor proliferation.

FAMA is a putative basic helix-loop-helix transcription factor whose activity is required to promote differentiation of stomatal guard cells and to halt proliferative divisions in their immediate precursors.

file:ARATH/FAMA/FAMA-ai-review.yaml

Gene review core function.