scholarly journals A Novel R2R3-MYB Gene LoMYB33 From Lily Is Specifically Expressed in Anthers and Plays a Role in Pollen Development

2021 ◽  
Vol 12 ◽  
Author(s):  
Xinyue Liu ◽  
Ze Wu ◽  
Jingxian Feng ◽  
Guozhen Yuan ◽  
Ling He ◽  
...  
Keyword(s):  
Amino Acids ◽  
Transcriptional Activation ◽  
Pollen Development ◽  
Biotic Resistance ◽  
Pollen Grains ◽  
Anther Development ◽  
Transactivation Domain ◽  
Reading Frame ◽  
Pollen Formation ◽  
R2r3 Myb

Lily (Lilium spp.) is an important commercial flower crop, but its market popularity and applications are adversely affected by severe pollen pollution. Many studies have examined pollen development in model plants, but few studies have been conducted on flower crops such as lily. GAMYBs are a class of R2R3-MYB transcription factors and play important roles in plant development and biotic resistance; their functions vary in different pathways, and many of them are involved in anther development. However, their function and regulatory role in lily remain unclear. Here, the GAMYB homolog LoMYB33 was isolated and identified from lily. The open reading frame of LoMYB33 was 1620 bp and encoded a protein with 539 amino acids localized in the nucleus and cytoplasm. Protein sequence alignment showed that LoMYB33 contained a conserved R2R3 domain and three BOX motifs (BOX1, BOX2, and BOX3), which were unique to the GAMYB family. LoMYB33 had transcriptional activation activity, and its transactivation domain was located within 90 amino acids of the C-terminal. LoMYB33 was highly expressed during the late stages of anther development, especially in pollen. Analysis of the promoter activity of LoMYB33 in transgenic Arabidopsis revealed that the LoMYB33 promoter was highly activated in the pollen of stage 12 to 13 flowers. Overexpression of LoMYB33 in Arabidopsis significantly retarded growth; the excess accumulation of LoMYB33 also negatively affected normal anther development, which generated fewer pollen grains and resulted in partial male sterility in transgenic plants. Silencing of LoMYB33 in lily also greatly decreased the amount of pollen. Overall, our results suggested that LoMYB33 might play an important role in the anther development and pollen formation of lily.

scholarly journals Functional characterization of the transactivation properties of the PDX-1 homeodomain protein.

1997 ◽  
Vol 17 (7) ◽  
pp. 3987-3996 ◽  
Author(s):  
M Peshavaria ◽  
E Henderson ◽  
A Sharma ◽  
C V Wright ◽  
R Stein
Keyword(s):  
Amino Acids ◽  
Gene Transcription ◽  
Transcriptional Activation ◽  
Functional Characterization ◽  
Insulin Gene ◽  
Regulatory Sequences ◽  
Homeodomain Protein ◽  
Transactivation Domain ◽  
Endogenous Insulin ◽  
Insulin Gene Transcription

Pancreas formation is prevented in mice carrying a null mutation in the PDX-1 homeoprotein, demonstrating a key role for this factor in development. PDX-1 can also bind to and activate transcription from cis-acting regulatory sequences in the insulin and somatostatin genes, which are expressed in pancreatic islet beta and delta cells, respectively. In this study, we compared the functional properties of PDX-1 with those of the closely related Xenopus homeoprotein XIHbox8. Analysis of chimeras between PDX-1, XIHbox8, and the DNA-binding domain of the Saccharomyces cerevisiae transcription factor GAL4 revealed that their transactivation domain was contained within the N-terminal region (amino acids 1 to 79). Detailed mutagenesis of this region indicated that transactivation is mediated by three highly conserved sequences, spanning amino acids 13 to 22 (subdomain A), 32 to 38 (subdomain B), and 60 to 73 (subdomain C). These sequences were also required by PDX-1 to synergistically activate insulin enhancer-mediated transcription with another key insulin gene activator, the E2A-encoded basic helix-loop-helix E2-5 and E47 proteins. These results indicated that N-terminal sequences conserved between the mammalian PDX-1 and Xenopus XIHbox8 proteins are important in transcriptional activation. Stable expression of the PDX-1 deltaABC mutant in the insulin- and PDX-1-expressing betaTC3 cell line resulted in a threefold reduction in the rate of endogenous insulin gene transcription. Strikingly, the level of the endogenous PDX-1 protein was reduced to very low levels in these cells. These results suggest that PDX-1 is not absolutely essential for insulin gene expression in betaTC3 cells. We discuss the possible significance of these findings for insulin gene transcription in islet beta cells.

Tapetum character states: analytical keys for tapetum types and activities

1997 ◽  
Vol 75 (9) ◽  
pp. 1448-1459 ◽  
Author(s):  
E. Pacini
Keyword(s):  
Pollen Development ◽  
Cell Walls ◽  
Pollen Grains ◽  
Cell Types ◽  
Plastid Differentiation ◽  
Pollen Coat ◽  
Tapetal Cells ◽  
Different Types ◽  
Compound Pollen ◽  
Pollen Formation

The different types of tapetum found in the spermatophyta are described, along with associated characters. The characters (taken singly, pairwise, or in multiple combinations) are (i) tapetum types; (ii) cell walls, tapetum types, and loculus; (iii) tapetal cells individually, tapetum types, and loculus; (iv) number of pollen grains enveloped by tapetal cells and type of pollen dispersing unit; (v) cell types and tapetum types; (vi) number of nuclei per cell and tapetum type; (vii) cycles of hyperactivity; (viii) exine formation; (ix) orbicles; (x) peritapetal membrane; (xi) plastid differentiation; (xii) stage of pollen development in which tapetal cells degenerate and type of pollen coat; (xiii) storage vacuoles; (xiv) sporophytic proteins; and (xv) devices of tapetal origin responsible for compound pollen formation and pollination. Examples are given and an analytical key of structural and functional diversity is provided as a helpful approach to the study of the tapetum. Key words: tapetum types, activities, pollen dispersing units.

scholarly journals A Cytological Study of Anther and Pollen Development in Chinquapin (Castanea henryi)

HortScience ◽  
2020 ◽  
Vol 55 (6) ◽  
pp. 945-950
Author(s):  
Weiping Zhong ◽  
Zhoujun Zhu ◽  
Fen Ouyang ◽  
Qi Qiu ◽  
Xiaoming Fan ◽  
...  
Keyword(s):  
Pollen Development ◽  
Lipid Droplets ◽  
Morphological Characteristics ◽  
Pollen Grains ◽  
Middle Layer ◽  
Anther Development ◽  
Mature Pollen ◽  
Anther Wall ◽  
Male Flowers ◽  
Microspore Stage

The normal development of anthers and the formation of functional pollen are the prerequisites for successful pollination and fertilization. In this study, we observed dynamic changes in inflorescence and anther development in the chinquapin (Castanea henryi) using stereomicroscopy, light microscopy, and transmission electron microscopy. We found that cytokinesis during meiosis in microsporocytes was of the simultaneous type, and that the tetrads were mainly tetrahedral. Mature pollen grains contained two cells with three germ pores. The anther wall was of the basic type and composed of epidermis, endothecium, middle layers, and tapetum. Mature anthers had no middle layer and tapetum. The tapetum was of the glandular type. At the early microspore stage, a large number of starch granules appeared in the endothecium, which was deformed at the late microspore stage. Lipid droplets appeared in tapetum during the early microspore stage, and a few lipid droplets were still found during tapetum degeneration. The mature pollen accumulated a large amount of starch and lipids. These findings demonstrated that the anther wall provides nutrients and protection for pollen development. There is relatively stable correspondence between the external morphological characteristics of male flowers and internal structure of anther development.

scholarly journals PRX9 and PRX40 are extensin peroxidases essential for maintaining tapetum and microspore cell wall integrity during Arabidopsis anther development

2018 ◽  
Author(s):  
Joseph R. Jacobowitz ◽  
Jing-Ke Weng
Keyword(s):  
Cell Wall ◽  
Pollen Development ◽  
Tapetal Cell ◽  
Pollen Grains ◽  
Anther Development ◽  
Cell Wall Integrity ◽  
Class Iii ◽  
Male Sterile ◽  
Male Gametes ◽  
Encoding Genes

AbstractPollen and microspore development is an essential step in the life cycle of all land plants that generate male gametes. Within flowering plants, pollen development occurs inside of the anther. Here, we report the identification of two class III peroxidase-encoding genes, PRX9 and PRX40, that are genetically redundant and essential for proper anther and pollen development in Arabidopsis thaliana. Arabidopsis double mutants devoid of functional PRX9 and PRX40 are male-sterile. The mutant anthers display swollen, hypertrophic tapetal cells and pollen grains, suggesting disrupted cell wall integrity. These phenotypes ultimately lead to nearly 100%-penetrant pollen degeneration upon anther maturation. Using immunochemical and biochemical approaches, we show that PRX9 and PRX40 are likely extensin peroxidases that contribute to the establishment of tapetal cell wall integrity during anther development. This work identifies PRX9 and PRX40 as the first extensin peroxidases to be described in Arabidopsis and highlights the importance of extensin cross-linking during plant development.

scholarly journals Three new dominant C1 suppressor alleles in Zea mays

1998 ◽  
Vol 71 (2) ◽  
pp. 127-132 ◽  
Author(s):  
TATJANA SINGER ◽  
ALFONS GIERL ◽  
PETER A. PETERSON
Keyword(s):  
Amino Acids ◽  
Transcriptional Activation ◽  
Stop Codon ◽  
Suppressive Effect ◽  
Wild Type ◽  
Activation Domain ◽  
Reading Frame ◽  
Transcriptional Activation Domain ◽  
Imprecise Excision ◽  
Carboxy Terminal

Three new dominant suppressor mutations of the C1 transcription regulator gene in maize – C1-IΔ1, C1-IΔ2 and C1-IΔ3 – are described that suppress anthocyanin colouration in kernels similar to the function of the C1-I standard inhibitor. The C1-IΔ mutations were induced by imprecise excision of an En/Spm transposon in the third exon of the C1 gene. These transposon footprints cause a frameshift in the C1 open reading frame that leads to truncated proteins due to an early stop codon 30 amino acids upstream of the wild-type C1 protein. Therefore, the C1-IΔ gene products lack the carboxy-terminal transcriptional activation domain of C1. The C1-I standard allele also lacks this domain and in addition differs in 17 amino acids from the wild-type C1 allele. The new C1-IΔ alleles provide evidence that deletion of the carboxy-terminal activation domain alone is sufficient to generate a dominant suppressive effect on the function of wild-type C1.

Microstrobilate Morphology, Microsporogenesis, and Pollen Formation in Western Hemlock

1974 ◽  
Vol 4 (4) ◽  
pp. 509-517 ◽  
Author(s):  
Rong H. Ho ◽  
John N. Owens
Keyword(s):  
Low Temperatures ◽  
Pollen Development ◽  
Pollen Grains ◽  
Western Hemlock ◽  
Abaxial Surface ◽  
Chromosome Behavior ◽  
The Common ◽  
Pollen Formation ◽  
Prothallial Cell

In western hemlock (Tsugaheterophylla (Raf.) Sarg.), the number of microstrobili per shoot averages 4.2. Each microstrobilus averages 13.9 bud scales and 17.2 microsporophylls. Microsporangia have a transverse dehiscence layer on the abaxial surface. There are an average of 1476 pollen grains per microsporangium and 17.4 million pollen grains per gram.Meiosis begins in the fall but stops at pachytene in November; it resumes in the middle of February and is completed in 1 week. Three weeks after the completion of meiosis the first prothallial cell forms and two weeks later the pollen grains reach maturity. Pollen shedding occurs 1.5 months after the resumption of meiosis and lasts for 2 weeks. Chromosome behavior and pollen formation are normal in 98.4% of the cells and in 99.7% of the pollen grains. The common abnormalities encountered are chiasma bridges, precocious disjunction, lagging chromosomes, and undersized pollen grains. The abnormalities may be attributed to the low temperatures occurring during meiosis and pollen development.

scholarly journals The Oncoprotein Tax Binds the SRC-1-Interacting Domain of CBP/p300 To Mediate Transcriptional Activation

2001 ◽  
Vol 21 (16) ◽  
pp. 5520-5530 ◽  
Author(s):  
Kirsten E. S. Scoggin ◽  
Aida Ulloa ◽  
Jennifer K. Nyborg
Keyword(s):  
Amino Acids ◽  
Transcriptional Activation ◽  
Molecular Mechanisms ◽  
Single Point ◽  
Terminal Region ◽  
Transactivation Domain ◽  
Human T Cell ◽  
Carboxy Terminal Region ◽  
Carboxy Terminal ◽  
Interacting Domain

ABSTRACT Oncogenesis associated with human T-cell leukemia virus (HTLV) infection is directly linked to the virally encoded transcription factor Tax. To activate HTLV-1 transcription Tax interacts with the cellular protein CREB and the pleiotropic coactivators CBP and p300. While extensively studied, the molecular mechanisms of Tax transcription function and coactivator utilization are not fully understood. Previous studies have focused on Tax binding to the KIX domain of CBP, as this was believed to be the key step in recruiting the coactivator to the HTLV-1 promoter. In this study, we identify a carboxy-terminal region of CBP (and p300) that strongly interacts with Tax and mediates Tax transcription function. Through deletion mutagenesis, we identify amino acids 2003 to 2212 of CBP, which we call carboxy-terminal region 2 (CR2), as the minimal region for Tax interaction. Interestingly, this domain corresponds to the steroid receptor coactivator 1 (SRC-1)-interacting domain of CBP. We show that a double point mutant targeted to one of the putative α-helical motifs in this domain significantly compromises the interaction with Tax. We also characterize the region of Tax responsible for interaction with CR2 and show that the previously identified transactivation domain of Tax (amino acids 312 to 319) participates in CR2 binding. This region of Tax corresponds to a consensus amphipathic helix, and single point mutations targeted to amino acids on the face of this helix abolish interaction with CR2 and dramatically reduce Tax transcription function. Finally, we demonstrate that Tax and SRC-1 bind to CR2 in a mutually exclusive fashion. Together, these studies identify a novel Tax-interacting site on CBP/p300 and extend our understanding of the molecular mechanism of Tax transactivation.

scholarly journals The Carboxy-Terminal Neh3 Domain of Nrf2 Is Required for Transcriptional Activation

2005 ◽  
Vol 25 (24) ◽  
pp. 10895-10906 ◽  
Author(s):  
Paul Nioi ◽  
Truyen Nguyen ◽  
Philip J. Sherratt ◽  
Cecil B. Pickett
Keyword(s):  
Amino Acids ◽  
Dna Binding ◽  
Transcriptional Activation ◽  
Transcriptional Activity ◽  
Redox Homeostasis ◽  
Binding Activity ◽  
Site Directed Mutagenesis ◽  
Transactivation Domain ◽  
Endogenous Gene ◽  
Nrf2 Target Gene

ABSTRACT Nrf2 is a transcription factor critical for the maintenance of cellular redox homeostasis. We have previously found that Nrf2 is a labile protein, and its activation in cells under stress involves mechanisms leading to its stabilization. As a modular protein, Nrf2 possesses distinct transactivation and DNA binding domains essential for its transcriptional activity. In this study, we found that the C-terminal “Neh3” domain of Nrf2 is also important for its activity. Deletion of the last 16 amino acids of the protein completely abolishes its ability to activate both reporter and endogenous gene expression. Using site-directed mutagenesis, we have identified a stretch of amino acids within this region that are essential for its activity and that are found to be conserved across species and among other members of the CNC-bZIP family. Importantly, deletion of the final 16 amino acids of Nrf2 does not influence its dimerizing capability, DNA binding activity, or subcellular localization, although it does increase the half-life of the protein. In addition, this region was found to be important for interaction with CHD6 (a chromo-ATPase/helicase DNA binding protein) in a yeast two-hybrid screen. RNA interference-mediated knockdown of CHD6 reduced both the basal and tert-butylhydroquinone-inducible expression of NQO1, a prototypical Nrf2 target gene. These data suggest that the Neh3 domain may act as a transactivation domain and that it is possibly involved in interaction with components of the transcriptional apparatus to affect its transcriptional activity.

Resolution of Channels in the Exine by Translocation of Colloidal Iron

1971 ◽  
Vol 29 ◽  
pp. 352-353
Author(s):  
John R. Rowley
Keyword(s):  
Phosphate Buffer ◽  
Pollen Development ◽  
Osmium Tetroxide ◽  
Pollen Grains ◽  
Deionized Water ◽  
Colloidal Iron ◽  
Fixed Material ◽  
Epilobium Angustifolium ◽  
Untreated Material ◽  
Microspore Mitosis

The morphology of the exine of many pollen grains, at the time of flowering, is such that one can suppose that transport of substances through the exine occurred during pollen development. Holes or channels, microscopic to submicroscopic, are described for a large number of grains. An inner part of the exine of Epilobium angustifolium L. and E. montanum L., which may be referred to as the endexine, has irregularly shaped channels early in pollen development although by microspore mitosis there is no indication of such channeling in chemically fixed material. The nucleus in microspores used in the experiment reported here was in prophase of microspore mitosis and the endexine, while lamellated in untreated grains, did not contain irregularly shaped channels. Untreated material from the same part of the inflorescence as iron treated stamens was examined following fixation with 0.1M glutaraldehyde in cacodylate-HCl buffer at pH 6.9 (315 milliosmoles) for 24 hrs, 4% formaldehyde in phosphate buffer at pH 7.2 (1,300 milliosmoles) for 12 hrs, 1% glutaraldehyde mixed with 0.1% osmium tetroxide for 20 min, osmium tetroxide in deionized water for 2 hrs and 1% glutaraldehyde mixed with 4% formaldehyde in 0.1M cacodylate-HCl buffer at pH 6.9 for two hrs.

scholarly journals A single nucleotide polymorphism in an R2R3 MYB transcription factor gene triggers the male sterility in soybean ms6 (Ames1)

2021 ◽  
Author(s):  
Junping Yu ◽  
Guolong Zhao ◽  
Wei Li ◽  
Ying Zhang ◽  
Peng Wang ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Glycine Max ◽  
Male Sterility ◽  
Bulked Segregant Analysis ◽  
Soybean Protein ◽  
Anther Development ◽  
Hybrid Breeding ◽  
Myb Transcription Factor ◽  
Male Sterile ◽  
R2r3 Myb

Abstract Key message Identification and functional analysis of the male sterile gene MS6 in Glycine max. Abstract Soybean (Glycine max (L.) Merr.) is an important crop providing vegetable oil and protein. The male sterility-based hybrid breeding is a promising method for improving soybean yield to meet the globally growing demand. In this research, we identified a soybean genic male sterile locus, MS6, by combining the bulked segregant analysis sequencing method and the map-based cloning technology. MS6, highly expressed in anther, encodes an R2R3 MYB transcription factor (GmTDF1-1) that is homologous to Tapetal Development and Function 1, a key factor for anther development in Arabidopsis and rice. In male sterile ms6 (Ames1), the mutant allele contains a missense mutation, leading to the 76th leucine substituted by histidine in the DNA binding domain of GmTDF1-1. The expression of soybean MS6 under the control of the AtTDF1 promoter could rescue the male sterility of attdf1 but ms6 could not. Additionally, ms6 overexpression in wild-type Arabidopsis did not affect anther development. These results evidence that GmTDF1-1 is a functional TDF1 homolog and L76H disrupts its function. Notably, GmTDF1-1 shows 92% sequence identity with another soybean protein termed as GmTDF1-2, whose active expression also restored the fertility of attdf1. However, GmTDF1-2 is constitutively expressed at a very low level in soybean, and therefore, not able to compensate for the MS6 deficiency. Analysis of the TDF1-involved anther development regulatory pathway showed that expressions of the genes downstream of TDF1 are significantly suppressed in ms6, unveiling that GmTDF1-1 is a core transcription factor regulating soybean anther development.

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