Interplay between positive and negative regulation by B3-type transcription factors is critical for the accurate expression of the ABA INSENSITIVE 4 gene.

The ABA-INSENSITIVE 4 transcription factor is key for the regulation of diverse aspects of plant development and environmental responses, including proper perception of hormonal and nutritional signals. ABI4 activity is highly regulated at the transcriptional and post-transcriptional levels leading to precise expression mainly in the developing seed and early seedling development. Based on genetic and molecular approaches in the current study we provide new insights into the central mechanism underpinning the transcriptional regulation of ABI4 during both seed and vegetative development. We identified a complex interplay between the LEC2 and ABI3 transcriptional activators and the HSI/VAL repressors that is critical for proper ABI4 expression. Interestingly, the regulation by these proteins relies on the two RY cis-acting motifs present two kb upstream of the ABI4 gene. Our analysis also shows that the chromatin landscape of the ABI4 loci is highly dependent on the LEC2 and HSI2/VAL proteins. LEC2 regulation extends to the vegetative development and the absence of this factor results in ABA- and sugar-insensitive signaling in the developing plant. This regulatory circuit functions as a major control module for the correct spatial-temporal expression of ABI4 and prevents its ectopic accumulation that is harmful to the plant.

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Analysis of Arabidopsis glucose insensitive mutants, gin5 and gin6, reveals a central role of the plant hormone ABA in the regulation of plant vegetative development by sugar

Genes & Development ◽

10.1101/gad.14.16.2085 ◽

2000 ◽

Vol 14 (16) ◽

pp. 2085-2096 ◽

Cited By ~ 1

Author(s):

Francisco Arenas-Huertero ◽

Analilia Arroyo ◽

Li Zhou ◽

Jen Sheen ◽

Patricia León

Keyword(s):

Aba Signaling ◽

Vegetative Development ◽

Glucose Signaling ◽

Putative Transcription Factor ◽

Normal Glucose ◽

Specific Accumulation ◽

Early Seedling ◽

Aba Insensitive

Sugars have signaling roles in a wide variety of developmental processes in plants. To elucidate the regulatory components that constitute the glucose signaling network governing plant growth and development, we have isolated and characterized two Arabidopsisglucose insensitive mutants, gin5 and gin6, based on a glucose-induced developmental arrest during early seedling morphogenesis. The T-DNA-tagged gin6 mutant abrogates the glucose-induced expression of a putative transcription factor, ABI4, previously shown to be involved in seed-specific abscisic acid (ABA) responses. Thus, ABI4 might be a regulator involved in both glucose- and seed-specific ABA signaling. The characterization of thegin5 mutant, on the other hand, reveals that glucose-specific accumulation of ABA is essential for hexokinase-mediated glucose responses. Consistent with this result, we show that three ABA-deficient mutants (aba1-1, aba2-1, andaba3-2) are also glucose insensitive. Exogenous ABA can restore normal glucose responses in gin5 and aba mutants but not in gin6 plants. Surprisingly, only abi4 andabi5-1 but not other ABA-insensitive signaling mutants (abi1-1, abi2-1, and abi3-1) exhibit glucose insensitivity, indicating the involvement of a distinct ABA signaling pathway in glucose responses. These results provide the first direct evidence to support a novel and central role of ABA in plant glucose responses mediated through glucose regulation of both ABA levels by GIN5 and ABA signaling by GIN6/ABI4.

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O-fucosylation of CPN20 by SPINDLY Derepresses Abscisic Acid Signaling During Seed Germination and Seedling Development

Frontiers in Plant Science ◽

10.3389/fpls.2021.724144 ◽

2021 ◽

Vol 12 ◽

Author(s):

Lin Liang ◽

Qi Wang ◽

Zihao Song ◽

Yaxin Wu ◽

Qing Liang ◽

...

Keyword(s):

Seed Germination ◽

Mammalian Cells ◽

Electron Transfer Dissociation ◽

Seedling Development ◽

Aba Signaling ◽

Early Seedling ◽

Aba Insensitive ◽

Early Seedling Development

SPINDLY is involved in some aspects of plant development. However, the nature of this protein as an O-fucosyltransferase was recently discovered. In this study, we show that SPINDLY (SPY) interacts with CPN20 in yeast two-hybrid and split-luc assays, and the interaction is promoted by ABA. CPN20 is a chloroplast-localized co-chaperonin that negatively regulates ABAR-mediated ABA signaling. By using Electron Transfer Dissociation-MS/MS analysis, two O-fucosylation sites, e.g., 116th and 119th threonines, were detected in ectopically expressed CPN20 in mammalian cells and in Arabidopsis. The O-fucosylation at both threonine residues was confirmed by in vitro peptide O-fucosylation assay. We further show that CPN20 accumulates in the chloroplast of spy mutants, suggesting that SPY negatively regulates CPN20 localization in the chloroplast. In vivo protein degradation assay along with CPN20 localization behavior suggest that import of CPN20 into the chloroplast is negatively regulated by SPY. Genetic analysis shows that ABA insensitive phenotypes of spy-3 in terms of seed germination and early seedling development are partially suppressed by the cpn20 mutation, suggesting that CPN20 acts downstream of SPY in this ABA signaling pathway and that there may exist other pathways in parallel with CPN20. Collectively, the above data support the notion that the O-fucosylation of CPN20 by SPY fine-tunes ABA signaling in Arabidopsis.

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Evidence for Redundancy But Not trans Factor-cis Element Coevolution in the Regulation of Drosophila Yp Genes

Genetics ◽

10.1093/genetics/152.2.605 ◽

1999 ◽

Vol 152 (2) ◽

pp. 605-616

Author(s):

Fabio Piano ◽

Michael J Parisi ◽

Roger Karess ◽

Michael P Kambysellis

Keyword(s):

Intergenic Region ◽

Fat Body ◽

Ectopic Expression ◽

Genomic Region ◽

Specific Pattern ◽

Sequence Comparisons ◽

Cis Acting ◽

Accurate Expression ◽

High Level

Abstract In Drosophila melanogaster and the endemic Hawaiian species D. grimshawi three Yolk protein (Yp) genes are expressed in a similar sex- and tissue-specific pattern. In contrast, DNA sequence comparisons of promoter/enhancer regions show low levels of similarity. We tested the functional significance of these observations by transforming D. melanogaster with the genomic region that includes the divergently transcribed D. grimshawi DgYp1 and DgYp2 genes; we found that the introduced genes were expressed in female fat body and in ovaries but not in males. Moreover, we found D. grimshawi proteins in the hemolymph and accumulating in ovaries. Using reporter constructs we showed that the intergenic region from D. grimshawi was sufficient to drive accurate expression, but some low level of ectopic expression was seen in males. Transforming D. melanogaster with constructs bearing deletions within the D. grimshawi intergenic region revealed only subtle effects in the overall level of expression, suggesting a high level of redundancy. Testing mutants in the sex-specific regulator doublesex revealed that it is capable of repressing the DgYp genes in males. Together, these data show that D. melanogaster trans-acting factors can regulate the in vivo pattern of DgYp expression and support the notion of a redundant and complex system of cis-acting elements.

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Arabidopsis LSH8 Positively Regulates ABA Signaling by Changing the Expression Pattern of ABA-Responsive Proteins

International Journal of Molecular Sciences ◽

10.3390/ijms221910314 ◽

2021 ◽

Vol 22 (19) ◽

pp. 10314

Author(s):

Jinpeng Zou ◽

Zhifang Li ◽

Haohao Tang ◽

Li Zhang ◽

Jingdu Li ◽

...

Keyword(s):

Transcription Factor ◽

Seed Germination ◽

Signaling Pathway ◽

Expression Pattern ◽

Large Scale ◽

Aba Signaling ◽

Wild Type ◽

Floral Organogenesis ◽

Early Seedling ◽

Aba Insensitive

Phytohormone ABA regulates the expression of numerous genes to significantly affect seed dormancy, seed germination and early seedling responses to biotic and abiotic stresses. However, the function of many ABA-responsive genes remains largely unknown. In order to improve the ABA-related signaling network, we conducted a large-scale ABA phenotype screening. LSH, an important transcription factor family, extensively participates in seedling development and floral organogenesis in plants, but whether its family genes are involved in the ABA signaling pathway has not been reported. Here we describe a new function of the transcription factor LSH8 in an ABA signaling pathway. In this study, we found that LSH8 was localized in the nucleus, and the expression level of LSH8 was significantly induced by exogenous ABA at the transcription level and protein level. Meanwhile, seed germination and root length measurements revealed that lsh8 mutant lines were ABA insensitive, whereas LSH8 overexpression lines showed an ABA-hypersensitive phenotype. With further TMT labeling quantitative proteomic analysis, we found that under ABA treatment, ABA-responsive proteins (ARPs) in the lsh8 mutant presented different changing patterns with those in wild-type Col4. Additionally, the number of ARPs contained in the lsh8 mutant was 397, six times the number in wild-type Col4. In addition, qPCR analysis found that under ABA treatment, LSH8 positively mediated the expression of downstream ABA-related genes of ABI3, ABI5, RD29B and RAB18. These results indicate that in Arabidopsis, LSH8 is a novel ABA regulator that could specifically change the expression pattern of APRs to positively mediate ABA responses.

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Plant peptide hormone signalling

Essays in Biochemistry ◽

10.1042/bse0580115 ◽

2015 ◽

Vol 58 ◽

pp. 115-131 ◽

Cited By ~ 17

Author(s):

Ayane Motomitsu ◽

Shinichiro Sawa ◽

Takashi Ishida

Keyword(s):

Communication Systems ◽

Cell Communication ◽

Peptide Hormone ◽

Peptide Hormones ◽

Target Cells ◽

Signalling Molecules ◽

Receptor Complexes ◽

Environmental Responses ◽

Plant Life Cycle ◽

Multicellular Organisms

The ligand–receptor-based cell-to-cell communication system is one of the most important molecular bases for the establishment of complex multicellular organisms. Plants have evolved highly complex intercellular communication systems. Historical studies have identified several molecules, designated phytohormones, that function in these processes. Recent advances in molecular biological analyses have identified phytohormone receptors and signalling mediators, and have led to the discovery of numerous peptide-based signalling molecules. Subsequent analyses have revealed the involvement in and contribution of these peptides to multiple aspects of the plant life cycle, including development and environmental responses, similar to the functions of canonical phytohormones. On the basis of this knowledge, the view that these peptide hormones are pivotal regulators in plants is becoming increasingly accepted. Peptide hormones are transcribed from the genome and translated into peptides. However, these peptides generally undergo further post-translational modifications to enable them to exert their function. Peptide hormones are expressed in and secreted from specific cells or tissues. Apoplastic peptides are perceived by specialized receptors that are located at the surface of target cells. Peptide hormone–receptor complexes activate intracellular signalling through downstream molecules, including kinases and transcription factors, which then trigger cellular events. In this chapter we provide a comprehensive summary of the biological functions of peptide hormones, focusing on how they mature and the ways in which they modulate plant functions.

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