Insights Into the Endocycle from Trichome Development

Larkin, John C.; Brown, Matthew L.; Churchman, Michelle L.

doi:10.1002/9780470988923.ch11

Cited by 9 publications

(8 citation statements)

References 55 publications

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“…Localized endoreduplication increases gene copy number, and thus could enhance the metabolic capacity of host cells at the infection site. Although it is not always the case, endoreduplication has been associated with both elevated metabolic activity and larger cell sizes (28,32). Consistent with this role at the site of PM infection at 5 dpi, we observed the enhanced expression of genes required to increase metabolic capacity (e.g., involved in transcription, translation, energy generation, and cofactor synthesis; SI Appendix).…”

Section: Genes Involved In Calcium Signaling and Redox Regulation Larsupporting

confidence: 78%

“…The enhanced expression of TFs involved in transcription, translation, and cell elongation at the site of infection is consistent with the observed endoreduplication. However, we did not observe statistically significant differences in expression for known TFs that mediate endoreduplication (28,29). This could be because most of these TFs were identified in developmental studies of specialized cells with enhanced ploidy (e.g., trichomes) or because their activity is not regulated at the transcript level.…”

Section: Genes Involved In Calcium Signaling and Redox Regulation Larmentioning

confidence: 57%

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Laser microdissection of Arabidopsis cells at the powdery mildew infection site reveals site-specific processes and regulators

Chandran

Inada²,

Hather³

et al. 2009

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

187

143

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To elucidate host processes and components required for the sustained growth and reproduction of the obligate biotrophic fungus Golovinomyces orontii on Arabidopsis thaliana , laser microdissection was used to isolate cells at the site of infection at 5 days postinfection for downstream global Arabidopsis expression profiling. Site-specific profiling increased sensitivity dramatically, allowing us to identify specific host processes, process components, and their putative regulators hidden in previous whole-leaf global expression analyses. For example, 67 transcription factors exhibited altered expression at the powdery mildew (PM) infection site, with subsets of these playing known or inferred roles in photosynthesis, cold/dehydration responses, defense, auxin signaling, and the cell cycle. Using integrated informatics analyses, we constructed putative regulatory networks for a subset of these processes and provided strong support for host cell cycle modulation at the PM infection site. Further experimentation revealed induced host endoreduplication occurred exclusively at the infection site and led us to identify MYB3R4 as a transcriptional regulator of this process. Induced endoreduplication was abrogated in myb3r4 mutants, and G. orontii growth and reproduction were reduced. This suggests that, by increasing gene copy number, localized endoreduplication serves as a mechanism to meet the enhanced metabolic demands imposed by the fungus, which acquires all its nutrients from the plant host.

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Section: Genes Involved In Calcium Signaling and Redox Regulation Larsupporting

confidence: 78%

Section: Genes Involved In Calcium Signaling and Redox Regulation Larmentioning

confidence: 57%

Laser microdissection of Arabidopsis cells at the powdery mildew infection site reveals site-specific processes and regulators

Chandran

Inada²,

Hather³

et al. 2009

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

187

143

View full text Add to dashboard Cite

show abstract

“…Trichomes have a unique branched cellular architecture; on leaves, they typically have three or four branches (Schellmann and Hülskamp, 2005). Arabidopsis trichomes are well established as a system for studying cell fate determination, cell morphogenesis and endoreplication (Larkin et al, 2007;Pesch and Hülskamp, 2009;Szymanski, 2009). The initiation of trichome development on Arabidopsis leaves is promoted by a transcription factor complex consisting of the bHLH transcription factors GL3 and EGL3, the Myb transcription factors GL1 and MYB23 and the WD-repeat protein TTG.…”

Section: Introductionmentioning

confidence: 99%

“…Mutations in a number of genes are known to affect endoreplication levels in trichomes (for a review, see Larkin et al, 2007). These include cell cycle components that affect the G1/S transition and DNA replication such as RBR (Desvoyes et al, 2006) and CDC6 (Castellano et al, 2004), and transcriptional regulators of trichome cell fate, such as GL3 and TRY (Hülskamp et al, 1994).…”

Section: Introductionmentioning

confidence: 99%

BRANCHLESS TRICHOMESlinks cell shape and cell cycle control inArabidopsistrichomes

et al. 2011

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SUMMARYEndoreplication, also called endoreduplication, is a modified cell cycle in which DNA is repeatedly replicated without subsequent cell division. Endoreplication is often associated with increased cell size and specialized cell shapes, but the mechanism coordinating DNA content with shape and size remains obscure. Here we identify the product of the BRANCHLESS TRICHOMES (BLT) gene, a protein of hitherto unknown function that has been conserved throughout angiosperm evolution, as a link in coordinating cell shape and nuclear DNA content in endoreplicated Arabidopsis trichomes. Loss-of-function mutations in BLT were found to enhance the multicellular trichome phenotype of mutants in the SIAMESE (SIM) gene, which encodes a repressor of endoreplication. Epistasis and overexpression experiments revealed that BLT encodes a key regulator of trichome branching. Additional experiments showed that BLT interacts both genetically and physically with STICHEL, another key regulator of trichome branching. Although blt mutants have normal trichome DNA content, overexpression of BLT results in an additional round of endoreplication, and blt mutants uncouple DNA content from morphogenesis in mutants with increased trichome branching, further emphasizing its role in linking cell shape and endoreplication.

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“…Arabidopsis trichomes, or shoot epidermal hairs, are a model for the study of endoreplication and other aspects of plant cell differentiation (Larkin et al 2003(Larkin et al , 2007. These trichomes are large branched single cells that protrude from the epidermis and have a DNA content of 16C to 32C (Melaragno et al 1993;Hü lskamp et al 1994).…”

mentioning

confidence: 99%

SIAMESE Cooperates With the CDH1-like Protein CCS52A1 to Establish Endoreplication in Arabidopsis thaliana Trichomes

et al. 2010

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Endoreplication, also known as endoreduplication, is a phyogenetically widespread modified version of the cell cycle in which DNA replication is not followed by cell division. The SIAMESE (SIM) gene of Arabidopsis thaliana encodes the founding member of a novel class of plant-specific cyclin-dependent kinase (CDK) inhibitors and is a key regulator of endoreplication during the development of trichomes (shoot epidermal hairs). Here, we have identified mutations in the CCS52A1 gene as genetic modifiers of the multicellular trichome phenotype of sim mutants. Loss-of-function ccs52A1 mutations dramatically enhance the multicellularity of sim mutants trichomes in double mutants, whereas overexpression of CCS52A1 completely suppresses the sim mutant phenotype. CCS52A1 encodes a CDH1/FZR-like protein, a class of proteins that function as activators of the anaphase-promoting complex. Unicellular ccs52A1 trichomes become multicellular upon overexpression of B-type cyclin, consistent with repression of the accumulation of mitotic cyclins in the developing trichome by CCS52A1. As these M-phase-specific cyclins are known to accumulate in sim mutant trichomes, our data suggest that CCS52A1 and SIM cooperate in repressing accumulation of mitotic cyclins to establish the trichome endocycle. Comparison with endoreplication pathways in Drosophila and mammals indicates that while these organisms all use similar components to initiate endoreplication, the components are deployed differently in each organism.

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Insights Into the Endocycle from Trichome Development

Cited by 9 publications

References 55 publications

Laser microdissection of Arabidopsis cells at the powdery mildew infection site reveals site-specific processes and regulators

Laser microdissection of Arabidopsis cells at the powdery mildew infection site reveals site-specific processes and regulators

BRANCHLESS TRICHOMESlinks cell shape and cell cycle control inArabidopsistrichomes

SIAMESE Cooperates With the CDH1-like Protein CCS52A1 to Establish Endoreplication in Arabidopsis thaliana Trichomes

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