scholarly journals Spike Activator 1, Encoding a bHLH, Mediates Axillary Bud Development and Spike Initiation in Phalaenopsis aphrodite

2019 ◽  
Vol 20 (21) ◽  
pp. 5406 ◽  
Author(s):  
Yi-Jyun Lin ◽  
Min-Jeng Li ◽  
Hung-Chien Hsing ◽  
Tien-Kuan Chen ◽  
Ting-Ting Yang ◽  
...  
Keyword(s):  
Axillary Bud ◽  
Bhlh Transcription Factor ◽  
Virus Induced Gene Silencing ◽  
Bud Development ◽  
Helix Loop Helix ◽  
Moth Orchid ◽  
Single Spike ◽  
Phalaenopsis Aphrodite ◽  
Spike Initiation ◽  
Gene Expression Levels

Double-spikes Phalaenopsis orchids have greater market value than those with single-spike. In this study, a gene designated as Spike Activator 1 (SPK1), which encodes a basic helix-loop-helix (bHLH) transcription factor, was isolated and characterized from Phalaenopsis aphrodite (moth orchid). SPK1 was highly expressed in the meristematic tissues. In the axillary bud, SPK1 was highly upregulated by a moderately low temperature of 20 °C but downregulated by a spike inhibition temperature of 30 °C. SPK1 protein is localized in the nucleus. Another bHLH, bHLH35, which is also highly expressed in young tissues in the same way as SPK1 was also identified. In contrast to SPK1, bHLH35 transcripts are downregulated at 20 °C but upregulated at 30 °C. Bimolecular florescence complementation assay and yeast two-hybrid assays indicated that SPK1 interacts with bHLH35 and forms a heterodimer. Virus-induced gene silencing (VIGS) showed that 7 out of 15 vector control plants produced double spikes but that only 1 out of 15 VIGS-spk1 plants produced double spikes. RT-qPCR results indicated that VIGS-spk1 downregulated gene expression levels of SPK1, FT, CYCB, and EXPA8. Overall, we propose that SPK1 plays an essential role in early axillary bud development and spike initiation of P. aphrodite.

scholarly journals Phototropins Mediate Chloroplast Movement in Phalaenopsis aphrodite (Moth Orchid)

2019 ◽  
Vol 60 (10) ◽  
pp. 2243-2254 ◽  
Author(s):  
Yi-Jyun Lin ◽  
Yu-Chung Chen ◽  
Kuan-Chieh Tseng ◽  
Wen-Chi Chang ◽  
Swee-Suak Ko
Keyword(s):  
Blue Light ◽  
Gene Evolution ◽  
Chloroplast Movement ◽  
Close Relative ◽  
Virus Induced Gene Silencing ◽  
Plant Growth And Development ◽  
Moth Orchid ◽  
Chloroplast Movements ◽  
Low Levels ◽  
Phalaenopsis Aphrodite

AbstractChloroplast movement is important for plants to avoid photodamage and to perform efficient photosynthesis. Phototropins are blue light receptors in plants that function in chloroplast movement, phototropism, stomatal opening, and they also affect plant growth and development. In this study, full-length cDNAs of two PHOTOTROPIN genes, PaPHOT1 and PaPHOT2, were cloned from a moth orchid Phalaenopsis aphrodite, and their functions in chloroplast movement were investigated. Phylogenetic analysis showed that PaPHOT1 and PaPHOT2 orthologs were highly similar to PHOT1 and PHOT2 of the close relative Phalaenopsis equestris, respectively, and clustered with monocots PHOT1 and PHOT2 orthologs, respectively. Phalaenopsis aphrodite expressed a moderate level of PaPHOT1 under low blue light of 5 μmol�m−2�s−1 (BL5) and a high levels of PaPHOT1 at >BL100. However, PaPHOT2 was expressed at low levels at <BL50 but expressed at high levels at > BL100. Analysis of light-induced chloroplast movements using the SPAD method indicated that orchid accumulated chloroplasts at <BL10. The chloroplast avoidance response was detectable at >BL25 and significant chloroplast avoidance movement was observed at >BL100. Virus-induced gene silencing of PaPHOTs in orchids showed decreased gene expression of PaPHOTs and reduced both chloroplast accumulation and avoidance responses. Heterologous expression of PaPHOT1 in Arabidopsis phot1phot2 double mutant recovered chloroplast accumulation response at BL5, but neither PaPHOT1 nor PaPHOT2 was able to restore mutant chloroplast avoidance at BL100. Overall, this study showed that phototropins mediate chloroplast movement in Phalaenopsis orchid is blue light-dependent but their function is slightly different from Arabidopsis which might be due to gene evolution.

scholarly journals PIF4 and PIF4-Interacting Proteins: At the Nexus of Plant Light, Temperature and Hormone Signal Integrations

2021 ◽  
Vol 22 (19) ◽  
pp. 10304
Author(s):  
Yang Xu ◽  
Ziqiang Zhu
Keyword(s):  
Target Genes ◽  
High Ambient Temperature ◽  
Interacting Proteins ◽  
Hormone Signaling ◽  
Helix Loop Helix ◽  
Robust Network ◽  
Global Transcriptome ◽  
Signaling Components ◽  
Reduce Gene Expression ◽  
Gene Expression Levels

Basic helix-loop-helix (bHLH) family transcription factor PHYTOCHROME INTERACTING FACTOR 4 (PIF4) is necessary for plant adaption to light or high ambient temperature. PIF4 directly associates with plenty of its target genes and modulates the global transcriptome to induce or reduce gene expression levels. However, PIF4 activity is tightly controlled by its interacting proteins. Until now, twenty-five individual proteins have been reported to physically interact with PIF4. These PIF4-interacting proteins act together with PIF4 and form a unique nexus for plant adaption to light or temperature change. In this review, we will discuss the different categories of PIF4-interacting proteins, including photoreceptors, circadian clock regulators, hormone signaling components, and transcription factors. These distinct PIF4-interacting proteins either integrate light and/or temperature cues with endogenous hormone signaling, or control PIF4 abundances and transcriptional activities. Taken together, PIF4 and PIF4-interacting proteins play major roles for exogenous and endogenous signal integrations, and therefore establish a robust network for plants to cope with their surrounding environmental alterations.

scholarly journals ATBS1-INTERACTING FACTOR 2 Negatively Modulates Pollen Production and Seed Formation in Arabidopsis

2021 ◽  
Vol 12 ◽  
Author(s):  
Yoon Kim ◽  
Sun-Ho Kim ◽  
Dong-Min Shin ◽  
Soo-Hwan Kim
Keyword(s):  
Pollen Grains ◽  
Starch Accumulation ◽  
Bhlh Transcription Factor ◽  
Pollen Production ◽  
Sucrose Transport ◽  
Seed Formation ◽  
Helix Loop Helix ◽  
Knockout Mutants ◽  
Auxin Signalling ◽  
Genes Encoding

ATBS1-INTERACTING FACTOR 2 (AIF2) is a non-DNA-binding basic-helix-loop-helix (bHLH) transcription factor. Here, we demonstrate that AIF2 negatively modulates brassinosteroid (BR)-induced, BRASSINAZOLE RESISTANT 1 (BZR1)-mediated pollen and seed formation. AIF2-overexpressing Arabidopsis plants (AIF2ox) showed defective pollen grains and seed production while two AIF2 knockout mutants, aif2-1 and aif2-1/aif4-1, displayed opposite phenotypes. Genes encoding BZR1-regulated positive factors of seed size determination (SHB1, IKU1, MINI3) were suppressed in AIF2ox and genes for negative factors (AP2 and ARF2) were enhanced. Surprisingly, BZR1-regulated pollen genes such as SPL, MS1, and TDF1 were aberrantly up-regulated in AIF2ox plants. This stage-independent abnormal expression may lead to a retarded and defective progression of microsporogenesis, producing abnormal tetrad microspores and pollen grains with less-effective pollen tube germination. Auxin plays important roles in proper development of flower and seeds: genes for auxin biosynthesis such as TCPs and YUCCAs as well as for positive auxin signalling such as ARFs were suppressed in AIF2ox flowers. Moreover, lipid biosynthesis- and sucrose transport-related genes were repressed, resulting in impaired starch accumulation. Contrarily, sucrose and BR repressed ectopic accumulation of AIF2, thereby increasing silique length and the number of seeds. Taken together, we propose that AIF2 is negatively involved in pollen development and seed formation, and that sucrose- and BR-induced repression of AIF2 positively promotes pollen production and seed formation in Arabidopsis.

Hxt encodes a basic helix-loop-helix transcription factor that regulates trophoblast cell development

Development ◽  
1995 ◽  
Vol 121 (8) ◽  
pp. 2513-2523 ◽  
Author(s):  
J.C. Cross ◽  
M.L. Flannery ◽  
M.A. Blanar ◽  
E. Steingrimsson ◽  
N.A. Jenkins ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Gene Promoter ◽  
Giant Cells ◽  
Placental Lactogen ◽  
Specific Gene ◽  
Bhlh Transcription Factor ◽  
Trophoblast Cells ◽  
Positive Role ◽  
Basic Helix Loop Helix ◽  
Helix Loop Helix

Trophoblast cells are the first lineage to form in the mammalian conceptus and mediate the process of implantation. We report the cloning of a basic helix-loop-helix (bHLH) transcription factor gene, Hxt, that is expressed in early trophoblast and in differentiated giant cells. A separate gene, Hed, encodes a related protein that is expressed in maternal deciduum surrounding the implantation site. Overexpression of Hxt in mouse blastomeres directed their development into trophoblast cells in blastocysts. In addition, overexpression of Hxt induced the differentiation of rat trophoblast (Rcho-1) stem cells as assayed by changes in cell adhesion and by activation of the placental lactogen-I gene promoter, a trophoblast giant cell-specific gene. In contrast, the negative HLH regulator, Id-1, inhibited Rcho-1 differentiation and placental lactogen-I transcription. These data demonstrate a role for HLH factors in regulating trophoblast development and indicate a positive role for Hxt in promoting the formation of trophoblast giant cells.

scholarly journals Inhibition of T Cell and Promotion of Natural Killer Cell Development by the Dominant Negative Helix Loop Helix Factor Id3

1997 ◽  
Vol 186 (9) ◽  
pp. 1597-1602 ◽  
Author(s):  
Mirjam H.M. Heemskerk ◽  
Bianca Blom ◽  
Garry Nolan ◽  
Alexander P.A. Stegmann ◽  
Arjen Q. Bakker ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Natural Killer ◽  
Progenitor Cells ◽  
Killer Cell ◽  
Cell Development ◽  
Dominant Negative ◽  
Bhlh Transcription Factor ◽  
Lineage Specification ◽  
Helix Loop Helix

Bipotential T/natural killer (NK) progenitor cells are present in the human thymus. Despite their bipotential capacity, these progenitors develop predominantly to T cells in the thymus. The mechanisms controlling this developmental choice are unknown. Here we present evidence that a member(s) of the family of basic helix loop helix (bHLH) transcription factors determines lineage specification of NK/T cell progenitors. The natural dominant negative HLH factor Id3, which blocks transcriptional activity of a number of known bHLH factors, was expressed in CD34+ progenitor cells by retrovirus-mediated gene transfer. Constitutive expression of Id3 completely blocks development of CD34+ cells into T cells in a fetal thymic organ culture (FTOC). In contrast, development into NK cells in an FTOC is enhanced. Thus, the activity of a bHLH transcription factor is necessary for T lineage differentiation of bipotential precursors, in the absence of which a default pathway leading to NK cell development is chosen. Our results identify a molecular switch for lineage specification in early lymphoid precursors of humans.

scholarly journals Genome-Wide Analysis of Basic Helix–Loop–Helix Superfamily Members Reveals Organization and Chilling-Responsive Patterns in Cabbage (Brassica oleracea var. capitata L.)

Genes ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 914
Author(s):  
Shan ◽  
Zhang ◽  
Yu ◽  
Wang ◽  
Li ◽  
...  
Keyword(s):  
Brassica Oleracea ◽  
Expression Profiles ◽  
Phylogenetic Analyses ◽  
Chilling Stress ◽  
Expression Patterns ◽  
Comprehensive Analysis ◽  
Bhlh Transcription Factor ◽  
Specific Expression ◽  
Basic Helix Loop Helix ◽  
Helix Loop Helix

Basic helix–loop–helix (bHLH) transcription factor (TF) family is commonly found in eukaryotes, which is one of the largest families of regulator proteins. It plays an important role in plant growth and development, as well as various biotic and abiotic stresses. However, a comprehensive analysis of the bHLH family has not been reported in Brassica oleracea. In this study, we systematically describe the BobHLHs in the phylogenetic relationships, expression patterns in different organs/tissues, and in response to chilling stress, and gene and protein characteristics. A total of 234 BobHLH genes were identified in the B. oleracea genome and were further clustered into twenty-three subfamilies based on the phylogenetic analyses. A large number of BobHLH genes were unevenly located on nine chromosomes of B. oleracea. Analysis of RNA-Seq expression profiles revealed that 21 BobHLH genes exhibited organ/tissue-specific expression. Additionally, the expression of six BobHLHs (BobHLH003, -048, -059, -093, -109, and -148) were significantly down-regulated in chilling-sensitive cabbage (CS-D9) and chilling-tolerant cabbage (CT-923). At 24h chilling stress, BobHLH054 was significantly down-regulated and up-regulated in chilling-treated CS-D9 and CT-923. Conserved motif characterization and exon/intron structural patterns showed that BobHLH genes had similar structures in the same subfamily. This study provides a comprehensive analysis of BobHLH genes and reveals several candidate genes involved in chilling tolerance of B. oleracea, which may be helpful to clarify the roles of bHLH family members and understand the regulatory mechanisms of BobHLH genes in response to the chilling stress of cabbage.

scholarly journals FIT, a regulatory hub for iron deficiency and stress signaling in roots, and FIT-dependent and -independent gene signatures

2020 ◽  
Vol 71 (5) ◽  
pp. 1694-1705 ◽  
Author(s):  
Birte Schwarz ◽  
Petra Bauer
Keyword(s):  
Transcription Factor ◽  
Protein Interactions ◽  
Fe Deficiency ◽  
Bhlh Transcription Factor ◽  
Root Cells ◽  
Gene Signatures ◽  
Helix Loop Helix ◽  
Independent Gene ◽  
Fe Uptake ◽  
Fe Acquisition

Abstract Iron (Fe) is vital for plant growth. Plants balance the beneficial and toxic effects of this micronutrient, and tightly control Fe uptake and allocation. Here, we review the role of the basic helix–loop–helix (bHLH) transcription factor FIT (FER-LIKE FE DEFICIENCY-INDUCED TRANSCRIPTION FACTOR) in Fe acquisition. FIT is not only essential, it is also a central regulatory hub in root cells to steer and adjust the rate of Fe uptake by the root in a changing environment. FIT regulates a subset of root Fe deficiency (–Fe) response genes. Based on a combination of co-expression network and FIT-dependent transcriptome analyses, we defined a set of FIT-dependent and FIT-independent gene expression signatures and co-expression clusters that encode specific functions in Fe regulation and Fe homeostasis. These gene signatures serve as markers to integrate novel regulatory factors and signals into the –Fe response cascade. FIT forms a complex with bHLH subgroup Ib transcription factors. Furthermore, it interacts with key regulators from different signaling pathways that either activate or inhibit FIT function to adjust Fe acquisition to growth and environmental constraints. Co-expression clusters and FIT protein interactions suggest a connection of –Fe with ABA responses and root cell elongation processes that can be explored in future studies.

scholarly journals Tomato bHLH132 Transcription Factor Controls Growth and Defense and Is Activated by Xanthomonas euvesicatoria Effector XopD During Pathogenesis

2019 ◽  
Vol 32 (12) ◽  
pp. 1614-1622 ◽  
Author(s):  
Jung-Gun Kim ◽  
Mary Beth Mudgett
Keyword(s):  
Transcription Factor ◽  
Protease Activity ◽  
Transcriptional Profiling ◽  
Bhlh Transcription Factor ◽  
Transcription Activator ◽  
Tal Effectors ◽  
Sumo Protease ◽  
Tal Effector ◽  
Helix Loop Helix ◽  
Xanthomonas Euvesicatoria

Effector-dependent manipulation of host transcription is a key virulence mechanism used by Xanthomonas species causing bacterial spot disease in tomato and pepper. Transcription activator-like (TAL) effectors employ novel DNA-binding domains to directly activate host transcription, whereas the non-TAL effector XopD uses a small ubiquitin-like modifier (SUMO) protease activity to represses host transcription. The targets of TAL and non-TAL effectors provide insight to the genes governing susceptibility and resistance during Xanthomonas infection. In this study, we investigated the extent to which the X. euvesicatoria non-TAL effector strain Xe85-10 activates tomato transcription to gain new insight to the transcriptional circuits and virulence mechanisms associated with Xanthomonas euvesicatoria pathogenesis. Using transcriptional profiling, we identified a putative basic helix-loop-helix (bHLH) transcription factor, bHLH132, as a pathogen-responsive gene that is moderately induced by microbe-associated molecular patterns and defense hormones and is highly induced by XopD during X. euvesicatoria infection. We also found that activation of bHLH132 transcription requires the XopD SUMO protease activity. Silencing bHLH132 mRNA expression results in stunted tomato plants with enhanced susceptibility to X. euvesicatoria infection. Our work suggests that bHLH132 is required for normal vegetative growth and development as well as resistance to X. euvesicatoria. It also suggests new transcription-based models describing XopD virulence and recognition in tomato.

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