scholarly journals The Maize Hairy Sheath Frayed1 (Hsf1) Mutation Alters Leaf Patterning through Increased Cytokinin Signaling

2020 ◽  
Vol 32 (5) ◽  
pp. 1501-1518 ◽  
Author(s):  
Michael G. Muszynski ◽  
Lindsay Moss-Taylor ◽  
Sivanandan Chudalayandi ◽  
James Cahill ◽  
Angel R. Del Valle-Echevarria ◽  
...  
Keyword(s):  
Cytokinin Signaling ◽  
Leaf Patterning

scholarly journals The maize Hairy Sheath Frayed1 (Hsf1) mutant alters leaf patterning through increased cytokinin signaling

2019 ◽  
Author(s):  
Michael G. Muszynski ◽  
Lindsay Moss-Taylor ◽  
Sivanandan Chudalayandi ◽  
James Cahill ◽  
Angel R. Del Valle-Echevarria ◽  
...  
Keyword(s):  
Zea Mays ◽  
Biochemical Analysis ◽  
Binding Pocket ◽  
Missense Mutations ◽  
Cytokinin Signaling ◽  
Leaf Morphogenesis ◽  
Developmental Patterns ◽  
Normal Morphology ◽  
Leaf Patterning ◽  
Margin Analysis

ABSTRACTLeaf morphogenesis requires growth polarized along three axes - proximal-distal, medial-lateral and abaxial-adaxial. Grass leaves display a prominent proximal-distal (P-D) polarity consisting of a proximal sheath separated from the distal blade by the auricle and ligule. Although proper specification of the four segments is essential for normal morphology, our knowledge is incomplete regarding the mechanisms which influence P-D specification in monocots like maize (Zea mays). Here we report the identification of the gene underlying the semi-dominant, leaf patterning, maize mutant Hairy Sheath Frayed1 (Hsf1). Hsf1 plants produce leaves with outgrowths consisting of proximal segments – sheath, auricle and ligule – emanating from the distal blade margin. Analysis of three independent Hsf1 alleles revealed gain-of-function missense mutations in the ligand binding domain of the maize cytokinin (CK) receptor Zea mays Histidine Kinase1 (ZmHK1) gene. Biochemical analysis and structural modeling suggest the mutated residues near the CK binding pocket affect CK binding affinity. Treatment of wild type seedlings with exogenous CK phenocopied the Hsf1 leaf phenotypes. Results from expression and epistatic analyses indicated the Hsf1 mutant receptor appears to be hypersignaling. Our results demonstrate that hypersignaling of CK in incipient leaf primordia can reprogram developmental patterns in maize.SummaryIncreased cytokinin signaling in the maize Hairy Sheath Frayed1 mutant modifies leaf development leading to changes in pattering, growth and cell identity.

scholarly journals The bacterial volatile N,N-dimethyl-hexadecylamine promotes Arabidopsis primary root elongation through cytokinin signaling and the AHK2 receptor

2021 ◽  
Vol 16 (4) ◽  
pp. 1879542
Author(s):  
Ernesto Vázquez-Chimalhua ◽  
Salvador Barrera-Ortiz ◽  
Eduardo Valencia-Cantero ◽  
José López-Bucio ◽  
León Francisco Ruiz-Herrera
Keyword(s):  
Root Elongation ◽  
Primary Root ◽  
Cytokinin Signaling

scholarly journals The Relationship between AGAMOUS and Cytokinin Signaling in the Establishment of Carpeloid Features

Plants ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 827
Author(s):  
Andrea Gómez-Felipe ◽  
Daniel Kierzkowski ◽  
Stefan de Folter
Keyword(s):  
Regulatory Network ◽  
Dependent Manner ◽  
Mads Box ◽  
Type B ◽  
Cytokinin Signaling ◽  
Reproductive Structures ◽  
Carpel Development ◽  
Gene Regulatory ◽  
The Relationship ◽  
Gynoecium Development

Gynoecium development is dependent on gene regulation and hormonal pathway interactions. The phytohormones auxin and cytokinin are involved in many developmental programs, where cytokinin is normally important for cell division and meristem activity, while auxin induces cell differentiation and organ initiation in the shoot. The MADS-box transcription factor AGAMOUS (AG) is important for the development of the reproductive structures of the flower. Here, we focus on the relationship between AG and cytokinin in Arabidopsis thaliana, and use the weak ag-12 and the strong ag-1 allele. We found that cytokinin induces carpeloid features in an AG-dependent manner and the expression of the transcription factors CRC, SHP2, and SPT that are involved in carpel development. AG is important for gynoecium development, and contributes to regulating, or else directly regulates CRC, SHP2, and SPT. All four genes respond to either reduced or induced cytokinin signaling and have the potential to be regulated by cytokinin via the type-B ARR proteins. We generated a model of a gene regulatory network, where cytokinin signaling is mainly upstream and in parallel with AG activity.

scholarly journals Zinc Finger Protein 6(ZFP6) regulates trichome initiation by integrating gibberellin and cytokinin signaling inArabidopsis thaliana

2013 ◽  
Vol 198 (3) ◽  
pp. 699-708 ◽  
Author(s):  
Zhongjing Zhou ◽  
Lili Sun ◽  
Yongqin Zhao ◽  
Lijun An ◽  
An Yan ◽  
...  
Keyword(s):  
Zinc Finger ◽  
Zinc Finger Protein ◽  
Cytokinin Signaling ◽  
Finger Protein

scholarly journals N-acetylglucosaminyltransferase II Is Involved in Plant Growth and Development Under Stress Conditions

2021 ◽  
Vol 12 ◽  
Author(s):  
Jae Yong Yoo ◽  
Ki Seong Ko ◽  
Bich Ngoc Vu ◽  
Young Eun Lee ◽  
Seok Han Yoon ◽  
...  
Keyword(s):  
Plant Growth ◽  
Growth And Development ◽  
Stress Conditions ◽  
Root Growth Inhibition ◽  
Loss Of Function ◽  
Plant Growth And Development ◽  
Cytokinin Signaling ◽  
Mannose Residue ◽  
Glcnac Residue ◽  
Physiological Importance

Alpha-1,6-mannosyl-glycoprotein 2-β-N-acetylglucosaminyltransferase [EC 2.4.1.143, N-acetylglucosaminyltransferase II (GnTII)] catalyzes the transfer of N-acetylglucosamine (GlcNAc) residue from the nucleotide sugar donor UDP-GlcNAc to the α1,6-mannose residue of the di-antennary N-glycan acceptor GlcNAc(Xyl)Man3(Fuc)GlcNAc2 in the Golgi apparatus. Although the formation of the GlcNAc2(Xyl)Man3(Fuc)GlcNAc2 N-glycan is known to be associated with GnTII activity in Arabidopsis thaliana, its physiological significance is still not fully understood in plants. To address the physiological importance of the GlcNAc2(Xyl)Man3(Fuc)GlcNAc2 N-glycan, we examined the phenotypic effects of loss-of-function mutations in GnTII in the presence and absence of stress, and responsiveness to phytohormones. Prolonged stress induced by tunicamycin (TM) or sodium chloride (NaCl) treatment increased GnTII expression in wild-type Arabidopsis (ecotype Col-0) but caused severe developmental damage in GnTII loss-of-function mutants (gnt2-1 and gnt2-2). The absence of the 6-arm GlcNAc residue in the N-glycans in gnt2-1 facilitated the TM-induced unfolded protein response, accelerated dark-induced leaf senescence, and reduced cytokinin signaling, as well as susceptibility to cytokinin-induced root growth inhibition. Furthermore, gnt2-1 and gnt2-2 seedlings exhibited enhanced N-1-naphthylphthalamic acid-induced inhibition of tropic growth and development. Thus, GnTII’s promotion of the 6-arm GlcNAc addition to N-glycans is important for plant growth and development under stress conditions, possibly via affecting glycoprotein folding and/or distribution.

scholarly journals Molecular mechanism of cytokinin-activated cell division in Arabidopsis

Science ◽  
2021 ◽  
Vol 371 (6536) ◽  
pp. 1350-1355
Author(s):  
Weibing Yang ◽  
Sandra Cortijo ◽  
Niklas Korsbo ◽  
Pawel Roszak ◽  
Katharina Schiessl ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Cell Division ◽  
Histidine Kinase ◽  
Feedback Loop ◽  
Apical Meristem ◽  
Nuclear Accumulation ◽  
Cytokinin Signaling ◽  
Positive Feedback Loop ◽  
Nuclear Shuttling ◽  
Stimulate Cell Proliferation

Mitogens trigger cell division in animals. In plants, cytokinins, a group of phytohormones derived from adenine, stimulate cell proliferation. Cytokinin signaling is initiated by membrane-associated histidine kinase receptors and transduced through a phosphorelay system. We show that in the Arabidopsis shoot apical meristem (SAM), cytokinin regulates cell division by promoting nuclear shuttling of Myb-domain protein 3R4 (MYB3R4), a transcription factor that activates mitotic gene expression. Newly synthesized MYB3R4 protein resides predominantly in the cytoplasm. At the G2-to-M transition, rapid nuclear accumulation of MYB3R4—consistent with an associated transient peak in cytokinin concentration—feeds a positive feedback loop involving importins and initiates a transcriptional cascade that drives mitosis and cytokinesis. An engineered nuclear-restricted MYB3R4 mimics the cytokinin effects of enhanced cell proliferation and meristem growth.

scholarly journals Down-Regulation of Cytokinin Receptor Gene SlHK2 Improves Plant Tolerance to Drought, Heat, and Combined Stresses in Tomato

Plants ◽  
2022 ◽  
Vol 11 (2) ◽  
pp. 154
Author(s):  
Naveed Mushtaq ◽  
Yong Wang ◽  
Junmiao Fan ◽  
Yi Li ◽  
Jing Ding
Keyword(s):  
Abiotic Stress Tolerance ◽  
Receptor Gene ◽  
Antioxidant Enzyme Activities ◽  
Plant Responses ◽  
Plant Tolerance ◽  
Combined Stress ◽  
Cytokinin Signaling ◽  
Down Regulation ◽  
Cytokinin Receptor ◽  
Combined Stresses

Environmental stresses negatively affect the growth and development of plants. Several previous studies have elucidated the response mechanisms of plants to drought and heat applied separately; however, these two abiotic stresses often coincide in environmental conditions. The global climate change pattern has projected that combined drought and heat stresses will tend to increase in the near future. In this study, we down-regulated the expression of a cytokinin receptor gene SlHK2 using RNAi and investigated the role of this gene in regulating plant responses to individual drought, heat, and combined stresses (drought + heat) in tomato. Compared to the wild-type (WT), SlHK2 RNAi plants exhibited fewer stress symptoms in response to individual and combined stress treatments. The enhanced abiotic stress tolerance of SlHK2 RNAi plants can be associated with increased membrane stability, osmoprotectant accumulation, and antioxidant enzyme activities. Furthermore, photosynthesis machinery was also protected in SlHK2 RNAi plants. Collectively, our results show that down-regulation of the cytokinin receptor gene SlHK2, and consequently cytokinin signaling, can improve plant tolerance to drought, heat, and combined stress.

scholarly journals Cytokinins Stimulate Plasmodesmatal Transport in Leaves

2021 ◽  
Vol 12 ◽  
Author(s):  
Wilson Horner ◽  
Jacob O. Brunkard
Keyword(s):  
Cell Walls ◽  
Fluorescent Protein ◽  
Plant Cells ◽  
Plant Biology ◽  
Negative Regulator ◽  
Cytokinin Signaling ◽  
Dynamic Changes ◽  
Cytokinin Receptors ◽  
Green Fluorescent ◽  
Development Regulation

Plant cells are connected by plasmodesmata (PD), nanoscopic channels in cell walls that allow diverse cytosolic molecules to move between neighboring cells. PD transport is tightly coordinated with physiology and development, although the range of signaling pathways that influence PD transport has not been comprehensively defined. Several plant hormones, including salicylic acid (SA) and auxin, are known to regulate PD transport, but the effects of other hormones have not been established. In this study, we provide evidence that cytokinins promote PD transport in leaves. Using a green fluorescent protein (GFP) movement assay in the epidermis of Nicotiana benthamiana, we have shown that PD transport significantly increases when leaves are supplied with exogenous cytokinins at physiologically relevant concentrations or when a positive regulator of cytokinin responses, ARABIDOPSIS HISTIDINE PHOSPHOTRANSFER PROTEIN 5 (AHP5), is overexpressed. We then demonstrated that silencing cytokinin receptors, ARABIDOPSIS HISTIDINE KINASE 3 (AHK3) or AHK4 or overexpressing a negative regulator of cytokinin signaling, AAHP6, significantly decreases PD transport. These results are supported by transcriptomic analysis of mutants with increased PD transport (ise1–4), which show signs of enhanced cytokinin signaling. We concluded that cytokinins contribute to dynamic changes in PD transport in plants, which will have implications in several aspects of plant biology, including meristem patterning and development, regulation of the sink-to-source transition, and phytohormone crosstalk.

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