The Arabidopsis Zinc Finger Protein 3 interferes with ABA and light signaling in seed germination and plant development

Seed germination is controlled by environmental signals, including light and endogenous phytohormones. Abscisic acid (ABA) inhibits, whereas gibberellin promotes, germination and early seedling development, respectively. Here, we report that ZFP3, a nuclear C2H2 zinc finger protein, acts as a negative regulator of ABA suppression of seed germination in Arabidopsis (Arabidopsis thaliana). Accordingly, regulated overexpression of ZFP3 and the closely related ZFP1, ZFP4, ZFP6, and ZFP7 zinc finger factors confers ABA insensitivity to seed germination, while the zfp3 zfp4 double mutant displays enhanced ABA susceptibility. Reduced expression of several ABA-induced genes, such as RESPONSIVE TO ABSCISIC ACID18 and transcription factor ABSCISIC ACID-INSENSITIVE4 (ABI4), in ZFP3 overexpression seedlings suggests that ZFP3 negatively regulates ABA signaling. Analysis of ZFP3 overexpression plants revealed multiple phenotypic alterations, such as semidwarf growth habit, defects in fertility, and enhanced sensitivity of hypocotyl elongation to red but not to far-red or blue light. Analysis of genetic interactions with phytochrome and abi mutants indicates that ZFP3 enhances red light signaling by photoreceptors other than phytochrome A and additively increases ABA insensitivity conferred by the abi2, abi4, and abi5 mutations. These data support the conclusion that ZFP3 and the related ZFP subfamily of zinc finger factors regulate light and ABA responses during germination and early seedling development

The low oxygen, oxidative and osmotic stress responses synergistically act through the ethylene response factor VII genes RAP2.12, RAP2.2 and RAP2.3

The ethylene response factor VII (ERF-VII) transcription factor RELATED TO APETALA2.12 (RAP2.12) was previously identified as an activator of the ALCOHOL DEHYDROGENASE1 promoter::luciferase (ADH1-LUC) reporter gene. Here we show that overexpression of RAP2.12 and its homologues RAP2.2 and RAP2.3 sustains ABA-mediated activation of ADH1 and activates hypoxia marker genes under both anoxic and normoxic conditions. Inducible expression of all three RAP2s conferred tolerance to anoxia, oxidative and osmotic stresses, and enhanced the sensitivity to abscisic acid (ABA). Consistently, the rap2.12-2 rap2.3-1 double mutant showed hypersensitivity to both submergence and osmotic stress. These findings suggest that the three ERF-VII-type transcription factors play roles in tolerance to multiple stresses that sequentially occur during and after submergence in Arabidopsis. Oxygen-dependent degradation of RAP2.12 was previously shown to be mediated by the N-end rule pathway. During submergence the RAP2.12, RAP2.2 and RAP2.3 are stabilized and accumulates in the nucleus affecting the transcription of stress response genes. We conclude that the stabilized RAP2 transcription factors can prolong the ABA-mediated activation of a subset of osmotic responsive genes (e.g. ADH1). We also show that RAP2.12 protein level is affected by the REALLY INTERESTING GENE (RING) domain containing SEVEN IN ABSENTIA of Arabidopsis thaliana 2 (SINAT2). Silencing of SINAT1/2 genes leads to enhanced RAP2.12 abundance independently of the presence or absence of its N-terminal degron. Taken together, our results suggest that RAP2.12 and its homologues RAP2.2 and RAP2.3 act redundantly in multiple stress responses. Alternative protein degradation pathways may provide inputs to the RAP2 transcription factors for the distinct stresses

Biochemical and gene expression analyses in different poplar clones: the selection tools for afforestation of halomorphic environments

Halomorphic soils cover a significant area in the Vojvodina region and represent ecological and economic challenges for agricultural and forestry sectors. In this study, four economically important Serbian poplar clones were compared according to their biochemical and transcriptomic responses towards mild and severe salt stress to select the most tolerant clones for afforestation of halomorphic soils. Three prospective clones of Populus deltoides (Bora-B229, Antonije-182/81 and PE19/66) and one of hybrid genetic background P. nigraxP. deltoides, e.g., P. x euramericana (Pannonia-M1) were hydroponically subjected to NaCl as a salt stress agent in a concentration range from 150 mM to 450 mM. Plant responses were measured at different time periods in the leaves. Biochemical response of poplar clones to salt stress was estimated by tracking several parameters such as different radical scavenging capacities (estimated by DPPH, FRAP and ABTS assays), accumulation of total phenolic content and flavonoids. Furthermore, accumulation of two osmolytes, glycine betaine and proline, were quantified. The genetic difference of those clones has been already shown by single nucleotide polymorphisms (SNPs) but this paper emphasized their differences regarding biochemical and transcriptomic salt stress responses. Five candidate genes, two putative poplar homologues of GRAS family TFs (PtGRAS17 and PtGRAS16), PtDREB2 of DREB family TFs and two abiotic stress-inducible genes (PtP5SC1, PtSOS1), were examined for their expression profiles. Results show that most salt stress-responsive genes were induced in clones M1 and PE19/66, thus showing they can tolerate salt environments with high concentrations and could be efficient in phytoremediation of salt environments. Clone M1 and PE19/66 has ABA-dependent mechanisms expressing the PtP5CS1 gene while clone 182/81 could regulate the expression of the same gene by ABA-independent pathway. To improve salt tolerance in poplar, two putative GRAS/SCL TFs and PtDREB2 gene seem to be promising candidates for genetic engineering of salt-tolerant poplar clones

Identification & functional characterization of the Arabidopsis ZINC FINGER PROTEIN 3

Abscisic acid regulates numerous processes such as seed desiccation, germination and responses to drought. Controlled cDNA Overexpression System (Papdi 2008) was employed to identify novel genes coding for important factors controlling ABA regulation. Screening for ABA insensitive germination of the transgenic plant population, transformed with the COS library, lead to the of identification several stress regulatory genes. Most pronounced Estradiol dependent ABA insenstitive germination was detected in A26 or A44 lines carrying either the full-length cDNAs, the small heat-shock protein HSP17.6A-cII (Papdi 2008) or a previously uncharacterized zinc-finger domain containing transcription factor protein. We have shown that ZFP3, a nuclear C2H2 zinc finger protein acts as a negative regulator of ABA- suppressed germination. Accordingly, regulated over-expression of ZFP3 and the closely related ZFP1, ZFP4, ZFP6 and ZFP7 zinc finger factors confers ABA insensitivity to seed germination while the zfp3 zfp4 double mutant displays enhanced ABA susceptibility. Reduced expression of several ABA-induced genes, such as RAB18 and ABI4 in ZFP3ox seedlings suggests that ZFP3 negatively regulates ABA signaling. ZFP3ox plants showed multiple phenotypic alterations, such as semidwarf growth habit, defects in fertility and enhanced sensitivity of hypocotyl elongation to red but not to far-red or blue light. Analysis of genetic interactions between phytochrome and abi mutants indicates that ZFP3 enhances red light signaling by photoreceptors other than phyA, and additively increases ABA insensitivity conferred by the abi2, abi4 and abi5 mutations. These data support the conclusion that ZFP3 and other members of the ZFP subfamily regulate light and ABA responses during germination and early seedling development

Assessment of Tumor Budding in Different Grades of Oral Squamous Cell Carcinoma

Introduction: Oral squamous cell carcinoma (OSCC) is the most common malignancy affecting the oral cavity in which patient prognosis and treatment primarily depend upon histological grading and clinical staging. Tumor budding has been recognized as a morphological marker of tumor invasion, which represents an aggressive feature of epithelial malignancies. This study was done to assess the activity of tumor budding in different grades of OSCC. Materials and Methods: An immunohistochemical study was performed on tissue sections obtained from 30 paraffin-embedded blocks of clinically and histologically diagnosed cases of OSCC. The sections were stained with pan cytokeratin and observed under high-power magnification. Tumor budding activity and cell nest size were assessed in different grades of OSCC. Results: A significant correlation was observed between tumor budding and cell nest size in OSCC. Conclusion: This study suggests the importance of using tumor buds as an additional parameter in the diagnosis and grading of OSCC