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An Arabidopsis mitochondria-localized RRL protein mediates abscisic acid signal transduction through mitochondrial retrograde regulation involving ABI4.

Yao X, Li J, Liu J, Liu K - J. Exp. Bot. (2015)

Bottom Line: High expression levels of RRL were found in germinating seeds and developing seedlings, as revealed by β-glucuronidase (GUS) staining of ProRRL-GUS transgenic lines.The analyses of the structure and function of mitochondria in the knockout rrl mutant showed that the disruption of RRL causes extensively internally vacuolated mitochondria and reduced ABA-stimulated reactive oxygen species (ROS) production.Furthermore, the results revealed that ABI4 is a downstream regulatory factor in RRL-mediated ABA signalling in seed germination and seedling growth.

View Article: PubMed Central - PubMed

Affiliation: National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China.

No MeSH data available.


Mitochondrial localization of the RRL–GFP fusion protein. (A–C) Subcellular localization of RRL–GFP fusion protein in leaf epidermal cells of Arabidopsis. (A) RRL–GFP, (B) MitoTracker Red staining, (C) co-localization of RRL–GFP and MitoTracker Red. Scale bar=10 μm. (D–F) Subcellular localization of RRL–GFP fusion protein in leaf epidermal cells of tobacco. (D) RRL–GFP, (E) mt-rk CD3-991 (a mitochondrial marker). (F) The overlay image (merge) shows co-localization of RRL–GFP and the mitochondria marker. Scale bar=30 μm. (This figure is available in colour at JXB online.)
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Figure 1: Mitochondrial localization of the RRL–GFP fusion protein. (A–C) Subcellular localization of RRL–GFP fusion protein in leaf epidermal cells of Arabidopsis. (A) RRL–GFP, (B) MitoTracker Red staining, (C) co-localization of RRL–GFP and MitoTracker Red. Scale bar=10 μm. (D–F) Subcellular localization of RRL–GFP fusion protein in leaf epidermal cells of tobacco. (D) RRL–GFP, (E) mt-rk CD3-991 (a mitochondrial marker). (F) The overlay image (merge) shows co-localization of RRL–GFP and the mitochondria marker. Scale bar=30 μm. (This figure is available in colour at JXB online.)

Mentions: A previous study revealed that an Arabidopsis mitochondria-localized protein RRG (At1G69380) with a domain of unknown function (DUF155) is required for cell division in the root meristem. Disruption of RRG causes the reduction of dividing cells, the rate of cell production, and endoreduplication, which thus decreases the meristem size and root growth rate (Zhou et al., 2011). At5G13610 is a homologous gene of At1G69380 and encodes another protein containing the DUF155 domain. At5G13610 shares 54% and 57% identity in nucleotide and amino acid sequences, respectively, with RRG (At1g69380) (see Supplementary Fig. S1A at JXB online) and was thus named RETARDED ROOT GROWTH-LIKE (RRL). The RRL gene is predicted to encode a novel protein with 402 amino acids (http://www.arabidopsis.org/servlets/TairObject?type=aa_sequence&id=1009134071). The RRL protein contains a conserved domain of unknown function (DUF155) and a putative C-terminal transmembrane domain (http://smart.embl-heidelberg.de/smart/show_motifs.pl) (see Supplementary Fig. S1B). To explore the subcellular localization of RRL protein, transgenic plants were generated with construct RRL–GFP in Arabidopsis. Fluorescence analyses of the expression of RRL–GFP revealed small punctate structures in leaf epidermal cells of the transgenic plants, which appeared to be localized to mitochondria. The mitochondrial localization of RRL–GFP was further confirmed by co-localization with a mitochondrion-selective dye MitoTracker Red (Fig. 1A–C). Additionally, the mitochondrial localization of RRL–GFP was also determined by tobacco leaf infiltration experiments with a well-known mitochondria marker, mt-rk CD3-991 (Nelson et al., 2007), which was generated with a red fluorescent protein, mCherry (Shaner et al., 2004). The RRL–GFP fusion protein co-localized with mt-rk CD3-991 by fluorescence analyses (Fig. 1D–F). These results showed that RRL is localized to mitochondria like RRG (Zhou et al., 2011; Fig. 1).


An Arabidopsis mitochondria-localized RRL protein mediates abscisic acid signal transduction through mitochondrial retrograde regulation involving ABI4.

Yao X, Li J, Liu J, Liu K - J. Exp. Bot. (2015)

Mitochondrial localization of the RRL–GFP fusion protein. (A–C) Subcellular localization of RRL–GFP fusion protein in leaf epidermal cells of Arabidopsis. (A) RRL–GFP, (B) MitoTracker Red staining, (C) co-localization of RRL–GFP and MitoTracker Red. Scale bar=10 μm. (D–F) Subcellular localization of RRL–GFP fusion protein in leaf epidermal cells of tobacco. (D) RRL–GFP, (E) mt-rk CD3-991 (a mitochondrial marker). (F) The overlay image (merge) shows co-localization of RRL–GFP and the mitochondria marker. Scale bar=30 μm. (This figure is available in colour at JXB online.)
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Figure 1: Mitochondrial localization of the RRL–GFP fusion protein. (A–C) Subcellular localization of RRL–GFP fusion protein in leaf epidermal cells of Arabidopsis. (A) RRL–GFP, (B) MitoTracker Red staining, (C) co-localization of RRL–GFP and MitoTracker Red. Scale bar=10 μm. (D–F) Subcellular localization of RRL–GFP fusion protein in leaf epidermal cells of tobacco. (D) RRL–GFP, (E) mt-rk CD3-991 (a mitochondrial marker). (F) The overlay image (merge) shows co-localization of RRL–GFP and the mitochondria marker. Scale bar=30 μm. (This figure is available in colour at JXB online.)
Mentions: A previous study revealed that an Arabidopsis mitochondria-localized protein RRG (At1G69380) with a domain of unknown function (DUF155) is required for cell division in the root meristem. Disruption of RRG causes the reduction of dividing cells, the rate of cell production, and endoreduplication, which thus decreases the meristem size and root growth rate (Zhou et al., 2011). At5G13610 is a homologous gene of At1G69380 and encodes another protein containing the DUF155 domain. At5G13610 shares 54% and 57% identity in nucleotide and amino acid sequences, respectively, with RRG (At1g69380) (see Supplementary Fig. S1A at JXB online) and was thus named RETARDED ROOT GROWTH-LIKE (RRL). The RRL gene is predicted to encode a novel protein with 402 amino acids (http://www.arabidopsis.org/servlets/TairObject?type=aa_sequence&id=1009134071). The RRL protein contains a conserved domain of unknown function (DUF155) and a putative C-terminal transmembrane domain (http://smart.embl-heidelberg.de/smart/show_motifs.pl) (see Supplementary Fig. S1B). To explore the subcellular localization of RRL protein, transgenic plants were generated with construct RRL–GFP in Arabidopsis. Fluorescence analyses of the expression of RRL–GFP revealed small punctate structures in leaf epidermal cells of the transgenic plants, which appeared to be localized to mitochondria. The mitochondrial localization of RRL–GFP was further confirmed by co-localization with a mitochondrion-selective dye MitoTracker Red (Fig. 1A–C). Additionally, the mitochondrial localization of RRL–GFP was also determined by tobacco leaf infiltration experiments with a well-known mitochondria marker, mt-rk CD3-991 (Nelson et al., 2007), which was generated with a red fluorescent protein, mCherry (Shaner et al., 2004). The RRL–GFP fusion protein co-localized with mt-rk CD3-991 by fluorescence analyses (Fig. 1D–F). These results showed that RRL is localized to mitochondria like RRG (Zhou et al., 2011; Fig. 1).

Bottom Line: High expression levels of RRL were found in germinating seeds and developing seedlings, as revealed by β-glucuronidase (GUS) staining of ProRRL-GUS transgenic lines.The analyses of the structure and function of mitochondria in the knockout rrl mutant showed that the disruption of RRL causes extensively internally vacuolated mitochondria and reduced ABA-stimulated reactive oxygen species (ROS) production.Furthermore, the results revealed that ABI4 is a downstream regulatory factor in RRL-mediated ABA signalling in seed germination and seedling growth.

View Article: PubMed Central - PubMed

Affiliation: National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China.

No MeSH data available.