SCREAM/ICE1andSCREAM2Specify Three Cell-State Transitional Steps Leading toArabidopsisStomatal Differentiation

Kanaoka, Masahiro M.; Pillitteri, Lynn Jo; Fujii, Hiroaki; Yoshida, Yuki; Bogenschutz, Naomi L.; Takabayashi, Junji; Zhu, Jian‐Kang; Torii, Keiko U.

doi:10.1105/tpc.108.060848

Cited by 471 publications

(617 citation statements)

References 30 publications

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“…pennellii leaves have several developmental features consistent with drought adaptation including reduced surface:volume ratio and changes in stomatal density (61). One developmental regulator that might be involved is SCREAM1, a positive regulator of stomatal index (the ratio of stomata to epidermal cells) (62,63). S. lycopersicum shows almost twofold lower levels of SCREAM1 (P = 0.00018).…”

Section: Expression Divergence Correlates With Phenotypic Differencesmentioning

confidence: 99%

Comparative transcriptomics reveals patterns of selection in domesticated and wild tomato

Koenig

Jiménez‐Gómez²,

Kimura

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

335

268

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Although applied over extremely short timescales, artificial selection has dramatically altered the form, physiology, and life history of cultivated plants. We have used RNAseq to define both gene sequence and expression divergence between cultivated tomato and five related wild species. Based on sequence differences, we detect footprints of positive selection in over 50 genes. We also document thousands of shifts in gene-expression level, many of which resulted from changes in selection pressure. These rapidly evolving genes are commonly associated with environmental response and stress tolerance. The importance of environmental inputs during evolution of gene expression is further highlighted by large-scale alteration of the light response coexpression network between wild and cultivated accessions. Human manipulation of the genome has heavily impacted the tomato transcriptome through directed admixture and by indirectly favoring nonsynonymous over synonymous substitutions. Taken together, our results shed light on the pervasive effects artificial and natural selection have had on the transcriptomes of tomato and its wild relatives.domestication | biotic stress | abiotic stress D omestication has long served as an important example of severe phenotypic divergence in response to selection. Darwin recognized the parallel between the processes of domestication and adaptation in the wild and used this analogy to emphasize the power of selection in generating phenotypic diversity (1). The genetic basis of domestication-associated phenotypes has been examined in several instances, most notably in maize, rice, tomato, and dogs (reviewed in refs. 2-5). The clear conclusion from these studies is that the rapid phenotypic divergence associated with domestication is often attributable to very few genetic loci (6). Improvements to DNA sequence technologies have allowed studies of the effect of domestication at the whole-genome level. Early population genetic analyses in maize found that very few genes (∼5%) show evidence of positive selection during domestication of maize (7), and recent work using whole-genome resequencing has found a similar proportion of the genome was under positive selection (8). Evidence for strong selective sweeps at a limited number of loci has also been found in rice and dog genomes (9). Together with the previous genetic mapping work, these studies support the model that relatively few mutations experienced extremely strong selection by humans during domestication.Although not the target of direct positive selection, the rest of the genome still experiences a dramatic shift in evolutionary pressures during domestication. Most characterized domestication events are associated with an extreme genetic bottleneck and alleviation of selective constraints in the original niche (10). These factors are predicted to increase the relative rate of nonsynonymous to synonymous (dN/dS) substitution, potentially resulting in the fixation of deleterious alleles (11). Previous studies comparing the distribution ...

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Section: Expression Divergence Correlates With Phenotypic Differencesmentioning

confidence: 99%

Comparative transcriptomics reveals patterns of selection in domesticated and wild tomato

Koenig

Jiménez‐Gómez²,

Kimura

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

335

268

View full text Add to dashboard Cite

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“…7) supports this hypothesis. scrm loss-of-function mutant produces aberrant stomatal complexes at low penetrance (Kanaoka et al, 2008), a phenotype shared by hdg2 (Fig. 5L-N).…”

Section: Research Articlementioning

confidence: 99%

“…Gal4DB-SCRM and Gal4DB-MUTE (Kanaoka et al, 2008) were used as positive and negative controls, respectively, of activation. These constructs were transformed into yeast strain AH109 according to manufacturer's protocols.…”

Section: Yeast One-hybrid Assays and Hdg2 Autoactivation Assaysmentioning

confidence: 99%

“…These bHLH proteins are necessary and sufficient for specifying each stomatal precursor state. Among them, MUTE and SCRM are capable of converting the aerial shoot epidermis into stomata when ectopically overexpressed or stabilized (Kanaoka et al, 2008;Pillitteri et al, 2008). By contrast, ectopic overexpressions of SPCH and FAMA confer excessive asymmetric entry divisions and the formation of guard cell-like cells, respectively (MacAlister et al, 2007;Ohashi-Ito and Bergmann, 2006;Pillitteri et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

“…The stomatal cell-state transitions are specified by combinatorial activities of five basic helix-loop-helix (bHLH) proteins, SPEECHLESS (SPCH), MUTE, FAMA, SCREAM (SCRM, also known as ICE1) and SCRM2 (Kanaoka et al, 2008;MacAlister et al, 2007;Ohashi-Ito and Bergmann, 2006;Pillitteri et al, 2007). These bHLH proteins are necessary and sufficient for specifying each stomatal precursor state.…”

Section: Introductionmentioning

confidence: 99%

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Arabidopsishomeodomain-leucine zipper IV proteins promote stomatal development and ectopically induce stomata beyond the epidermis

et al. 2013

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SUMMARYThe shoot epidermis of land plants serves as a crucial interface between plants and the atmosphere: pavement cells protect plants from desiccation and other environmental stresses, while stomata facilitate gas exchange and transpiration. Advances have been made in our understanding of stomatal patterning and differentiation, and a set of 'master regulatory' transcription factors of stomatal development have been identified. However, they are limited to specifying stomatal differentiation within the epidermis. Here, we report the identification of an Arabidopsis homeodomain-leucine zipper IV (HD-ZIP IV) protein, HOMEODOMAIN GLABROUS2 (HDG2), as a key epidermal component promoting stomatal differentiation. HDG2 is highly enriched in meristemoids, which are transient-amplifying populations of stomatal-cell lineages. Ectopic expression of HDG2 confers differentiation of stomata in internal mesophyll tissues and occasional multiple epidermal layers. Conversely, a loss-of-function hdg2 mutation delays stomatal differentiation and, rarely but consistently, results in aberrant stomata. A closely related HD-ZIP IV gene, Arabidopsis thaliana MERISTEM LAYER1 (AtML1), shares overlapping function with HDG2: AtML1 overexpression also triggers ectopic stomatal differentiation in the mesophyll layer and atml1 mutation enhances the stomatal differentiation defects of hdg2. Consistently, HDG2 and AtML1 bind the same DNA elements, and activate transcription in yeast. Furthermore, HDG2 transactivates expression of genes that regulate stomatal development in planta. Our study highlights the similarities and uniqueness of these two HD-ZIP IV genes in the specification of protodermal identity and stomatal differentiation beyond predetermined tissue layers.

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Epidermis: Outer Cell Layer of the Plant

Glover

Airoldi

Moyroud

2016

Encyclopedia of Life Sciences

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The epidermis is the protective outer layer of clonally related cells covering all plant organs. It is composed of a number of specialised cell types which differentiate from the basal epidermal cell in adaptively significant frequencies and patterns. The epidermis is unique in developing solely through anticlinal divisions, generating a sheet of cells overlying the rest of the plant. This sheet is connected physically and biochemically to the cell layers below, with information exchange occurring in both directions. The specialised cell types within the epidermis develop either through communication among themselves, or, in some cases, through communication also with the underlying cell layers. Brief descriptions of the molecular genetic control of trichomes, stomata, root hairs and petal conical‐papillate epidermal cells are provided here, along with a summary of the role of the cuticle in epidermal cell morphology and of the interplay between cuticle regulation and cell morphology. Key Concepts The plant epidermis is a single layer of clonally related cells. Plant epidermis fulfils a basic protective function, but specialised cells within the epidermis have specific roles. The seedling epidermis arises by isolation of the outer layer during embryogenesis. The aerial epidermis and the root epidermis originate later, in the shoot apical meristem and in the root apical meristem, respectively. Stomatal guard cells allow gas exchange, and their patterning is controlled by cell‐lineage‐based developmental mechanisms. Trichomes protect the plant from herbivores, and their patterning is controlled by cell–cell interactions. Root hairs increase surface area for water and nutrient uptake, and are patterned according to positional signals. The cuticle overlying the epidermis can contribute to epidermal cell shape and function. There is interplay between the regulation of epidermal cell shape and the regulation of cuticle production.

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SCREAM/ICE1andSCREAM2Specify Three Cell-State Transitional Steps Leading toArabidopsisStomatal Differentiation

Cited by 471 publications

References 30 publications

Comparative transcriptomics reveals patterns of selection in domesticated and wild tomato

Comparative transcriptomics reveals patterns of selection in domesticated and wild tomato

Arabidopsishomeodomain-leucine zipper IV proteins promote stomatal development and ectopically induce stomata beyond the epidermis

Epidermis: Outer Cell Layer of the Plant

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