Os05g0195200

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OsTZF1 is a member of the CCCH-type zinc finger gene family in rice (Oryza sativa)[1][2].

Annotated Information

Function

  • RNA-binding assays indicated that OsTZF1 binds to U-rich regions in the 39 untranslated region of messenger RNAs, suggesting that OsTZF1 might be associated with RNA metabolism of stress-responsive genes. OsTZF1 may serve as a useful biotechnological tool for the improvement of stress tolerance in various plants through the control of RNA metabolism of stress-responsive genes. OsTZF1 acts as a negative regulator of leaf senescence in rice under stress conditions and confers abiotic stress tolerance[1].
  • OsTZF1 affects germination and subsequent rice seedling growth. Constitutive overexpression of OsTZF1 caused pleiotropic effects on the phenotype of rice plants. OsTZF1-OX Plants exhibit high-salt and drought stress tolerance OsTZF1 positively regulates highsalt stress tolerance and drought stress tolerance in rice plants. OsTZF1 confers increased tolerance to oxidative stress[1].
  • OsTZF1 binds RNA in vitro, it binds to U-rich regions, AREs, and ARE-like motifs. As a cytoplasmic TZF protein, OsTZF1 is involved in photomorphogenesis and ABA responses in rice seedlings. OsTZF1 encodes a cytoplasm-localized tandem zinc finger protein and is regulated by both ABA and phytochrome-mediated light signaling. OsTZF1 functions in phytochrome-mediated light and ABA responses in rice[2].

GO assignment(s): GO:0003676, GO:0008270

Mutation

  • POsTZF1:GUS[1]:

Transgenic rice plants containing a 1,417-bp OsTZF1 promoter fragment fused to the GUS reporter gene (POsTZF1:GUS). Quantitative analysis of GUS activity in the POsTZF1:GUS plants confirmed that the promoter region of OsTZF1 regulates the induction of this gene in response to ABA and NaCl. Histochemical GUS activity was mainly detected in the aerial parts of POsTZF1:GUS plants, and its intensity increased in response to ABA and NaCl.

  • OsTZF1-OX, OsTZF1-RNAi[1]:
    • Differences in seed germination time affect subsequent growth; the growth of OsTZF1-OX seedlings was slow, while OsTZF1-RNAi seedlings showed enhanced growth compared with controls at 10 d after seed germination.
    • The OsTZF1-OX seedlings planted in soil grew normally, and there was no difference in the growth of OsTZF1-OX, OsTZF1-RNAi, and control plants.
    • At the bolting stage, the OsTZF1-OX and control plants were indistinguishable. The OsTZF1-OX plants exhibited delayed senescence of leaves and retained more photosynthetic activity compared with controls after the start of seed setting.
    • Interestingly, during the heading and seed-setting stages, OsTZF1-OX leaves were greener but developed a number of brown lesions that increased in frequency over time. The seeds of OsTZF1-OX were also brownish in appearance compared with controls at harvest.
  • RNA interference (RNAi)knocked-down plants (OsTZF1-RNAi) showed early seed germination', enhanced seedling growth, and early leaf senescence compared with controls.
  • Ubi:OsTZF1-OX plants showed improved tolerance to high-salt and drought stresses and vice versa for OsTZF1-RNAi plants.
  • Microarray analysis revealed that genes related to stress, reactive oxygen species homeostasis, and metal homeostasis were regulated in the Ubi:OsTZF1-OX plants.
  • OsTZF1-overexpression lines[2]:
    • #2
    • #8
  • mutants[2]:
    • phyA
    • phyB
    • phyAphyC

Expression

Figure 1. Expression profiles of OsTZF1 under different stress and hormone treatments.(from reference [1]).
  • Expression of OsTZF1 was induced by drought, high-salt stress, and hydrogen peroxide. OsTZF1 gene expression was also induced by abscisic acid(ABA), methyl jasmonate, and salicylic acid(SA). Transgenic rice plants overexpressing OsTZF1 driven by a maize (Zea mays) ubiquitin promoter (Ubi:OsTZF1-OX [for overexpression]) exhibited delayed seed germination, growth retardation at the seedling stage, and delayed leaf senescence. Histochemical activity of bglucuronidase in transgenic rice plants containing the promoter of OsTZF1 fused with b-glucuronidase was observed in callus, coleoptile, young leaf, and panicle tissues[1].
  • Expression of OsTZF1 in response to dehydration, ABA, NaCl, and hydrogen peroxide (H2O2) was analyzed by RNA gel-blot analysis to investigate time-dependent induction patterns, the OsTZF1 transcript accumulated in seedlings within 2 h following ABA, NaCl, and H2O2 treatments. In contrast, expression of the OsTZF1 gene induction peaked after 5 h and then decreased slightly over 24 h of dehydration stress treatment (Fig.1A). There was no significant accumulation of OsTZF1 mRNA in seedlings treated with water only (Fig. 1A). The expression of OsTZF1 in rice seedlings was also up-regulated following treatment with exogenous salicylic acid (SA) or jasmonic acid (JA; Fig. 1B)[1].
  • The OsTZF1 gene was expressed at relatively high levels in leaves and shoots, although its transcripts were detected in various organs[2].
    • Red light (R)- and far-red light (FR)-mediated repression of OsTZF1 gene expression was attributed to phytochrome B (phyB) and phytochrome C (phyC), respectively.
    • In addition, OsTZF1 expression was regulated by salt, PEG, and ABA. Overexpression of OsTZF1 caused a long leaf sheath relative to wild type (WT) under R and FR.
    • Moreover, ABA-induced growth inhibition of rice seedlings was marked in the OsTZF1-overexpression lines compared with WT, suggesting the positive regulation of OsTZF1 to ABA responses. Genomewide expression analysis further revealed that OsTZF1 also functions in other hormone or stress responses[2].
  • Transgenic plants overexpressing OsTZF1 show hypersensitivity to exogenous ABA and hyposensitivity to R and FR during seedling growth[2].

Subcellular localization

  • Upon stress, OsTZF1-green fluorescent protein localization was observed in the cytoplasm and cytoplasmic foci[1].
    • OsTZF1 has dynamic subcellular localization patterns in the cytoplasm and probably the nucleus:
      • Under normal growth conditions, OsTZF1 was predominantly localized in the cytoplasm of root meristem cells and was occasionally observed in cytoplasmic foci. OsTZF1-GFP was rarely observed in the nucleus of root cells at the young seedling stage.
      • ABA and NaCl enhanced the formation of cytoplasmic foci in root cells. The size, shape, and number of these cytoplasmic foci varied depending on the condition of plants and the type of roots. These cytoplasmic foci resembled processing bodies (PBs) and stress granules (SGs) where mRNA turnover and translational repression take place[3][4].
      • OsTZF1 and PABP8 colocalized in comparatively large cytoplasmic foci, considered to be SGs.
      • In onion (Allium cepa) epidermal cells, OsTZF1 was localized in the cytoplasm and cell membran.
  • The OsTZF1-GFP signal was detected in the cytoplasm, whereas GFP alone was distributed throughout the cell, the cytoplasmic localization of TZF proteins is likely a common feature in plants[2].

Evolution

  • OsDOS is similar to OsTZF1 with an amino acid identity of 73 % in rice, was reported to have a nuclear localization in root tips of transgenic rice plants[2][5].
  • OsTZF1 is an intronless gene encoding a predicted protein of 402 amino acids with a calculated molecular mass of 42.72 kDa. The TZF motif in OsTZF1 contains two tandem zinc finger CCCH motifs, CX7CX5CX3H and CX5CX4CX3H, separated by 16 amino acids. In addition, an atypical zinc finger motif (CX5HX4CX3H) and two other motifs (SHDWTEC and ARRRDPR) were observed upstream of the TZF motifs. These motifs have only been observed in plants and are highly conserved in the rice and Arabidopsis genomes[6].
  • Thus, OsTZF1 belongs to a subset of CCCH-type zinc finger proteins[2].

Knowledge Extension

Figure 2. Current model for plant arginine-rich tandem CCCH zinc finger (RR-TZF) protein functions.(from reference [7]).
  • Plant RR-TZFs are involved in RNA regulation (Fig. 2), plant RR-TZFs can bind specific RNA elements, interact with protein partners, localize to PBs and SGs, and affect plant growth, development, stress response and RNA stability (Fig. 2)[7].
  • Although information has been gained rapidly in the past few years, the exact functions and underlying molecular mechanisms for plant RR-TZF proteins remain elusive. One of the challenges is functional redundancy of the gene families. Because many RR-TZF single KO mutants display subtle or no phenotypes, overexpression has been used as a common approach for functional characterization. This has raised the possibility that the observed phenotypes may be biased due to non-specific effects caused by ectopic expression[7].
  • Zinc finger proteins constitute a large and diverse transcription factor family. Based on their individual finger structure and spacing, zinc finger proteins are further divided into nine types (C2H2, C8, C6, C3HC4, C2HC, C2HC5, C4, C4HC3, and CCCH, with C and H representing cysteine and histidine, respectively) that are generally associated with specific molecular functions[8]. Many zinc finger proteins are involved in abiotic and biotic stresses[9][10].
  • Overexpression of GhZFP1 from cotton in tobacco enhanced tolerances to drought, salt and salicylic acid (SA) as well as fungal disease tolerance. CCCH-type zinc finger proteins may be unique to higher plant species[8].
  • Among the different types of zinc finger proteins, the CCCH proteins are a large family containing 1–6 copies of CCCH-type motifs. A genome-wide analysis of the CCCH gene family identified a total of 68, 67, 68, and 91 CCCH genes in Arabidopsis, Oryza sativa[11], maize[9], and Populus[12], respectively. Although CCCH zinc finger proteins belong to a large family, their functions in plants are poorly understood. Only a few CCCH proteins have been characterized and shown to play diverse roles in plant developmental processes and environmental responses[10][11][12].

Labs working on this gene

  • Biological Resources and Post-harvest Division, Japan International Research Center for Agricultural Sciences, Tsukuba, Ibaraki 305–8686, Japan
  • Laboratory of Plant Molecular Physiology and Laboratory of Analytical Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, Bunkyo-ku, Tokyo 113–8657, Japan
  • Department of Agricultural Chemistry, Faculty of Agriculture, Meiji University, Kawasaki, Kanagawa 214–8571, Japan; and RIKEN Plant Science Center, Yokohama, Kanagawa 230–0045, Japan
  • High-Tech Research Center, Shandong Academy of Agricultural Sciences, Jinan 250100, People’s Republic of China
  • College of Life Sciences, Shandong University of Technology, Zibo 255049, People’s Republic of China
  • Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China
  • Laboratory of Crop Genetic Improvement and Biotechnology, Huanghuaihai, Ministry of Agriculture, Jinan 250100, People’s Republic of China


References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 Jan A, Maruyama K, Todaka D, et al. OsTZF1, a CCCH-tandem zinc finger protein, confers delayed senescence and stress tolerance in rice by regulating stress-related genes[J]. Plant physiology, 2013, 161(3): 1202-1216.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 Zhang C, Zhang F, Zhou J, et al. Overexpression of a phytochrome-regulated tandem zinc finger protein gene, OsTZF1, confers hypersensitivity to ABA and hyposensitivity to red light and far-red light in rice seedlings[J]. Plant cell reports, 2012, 31(7): 1333-1343.
  3. ↑ Parker R, Sheth U. P bodies and the control of mRNA translation and degradation[J]. Molecular cell, 2007, 25(5): 635-646.
  4. ↑ Balagopal V, Parker R. Polysomes, P bodies and stress granules: states and fates of eukaryotic mRNAs[J]. Current opinion in cell biology, 2009, 21(3): 403-408.
  5. ↑ Kong Z, Li M, Yang W, et al. A novel nuclear-localized CCCH-type zinc finger protein, OsDOS, is involved in delaying leaf senescence in rice[J]. Plant physiology, 2006, 141(4): 1376-1388.
  6. ↑ Pomeranz M C, Hah C, Lin P C, et al. The Arabidopsis tandem zinc finger protein AtTZF1 traffics between the nucleus and cytoplasmic foci and binds both DNA and RNA[J]. Plant physiology, 2010, 152(1): 151-165.
  7. ↑ 7.0 7.1 7.2 Bogamuwa S P, Jang J C. Tandem CCCH Zinc Finger Proteins in Plant Growth, Development, and Stress Response[J]. Plant and Cell Physiology, 2014: pcu074.
  8. ↑ 8.0 8.1 Guo Y H, Yu Y P, Wang D, et al. GhZFP1, a novel CCCH‐type zinc finger protein from cotton, enhances salt stress tolerance and fungal disease resistance in transgenic tobacco by interacting with GZIRD21A and GZIPR5[J]. New Phytologist, 2009, 183(1): 62-75.
  9. ↑ 9.0 9.1 Peng X, Zhao Y, Cao J, et al. CCCH-type zinc finger family in maize: genome-wide identification, classification and expression profiling under abscisic acid and drought treatments[J]. PloS one, 2012, 7(7): e40120.
  10. ↑ 10.0 10.1 Min D H, Zhao Y, Huo D Y, et al. Isolation and identification of a wheat gene encoding a zinc finger protein (TaZnFP) responsive to abiotic stresses[J]. Acta Physiologiae Plantarum, 2013, 35(5): 1597-1604.
  11. ↑ 11.0 11.1 Wang D, Guo Y, Wu C, et al. Genome-wide analysis of CCCH zinc finger family in Arabidopsis and rice[J]. BMC genomics, 2008, 9(1): 44.
  12. ↑ 12.0 12.1 Chai G, Hu R, Zhang D, et al. Comprehensive analysis of CCCH zinc finger family in poplar (Populus trichocarpa)[J]. BMC genomics, 2012, 13(1): 253.

Structured Information

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