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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.


Overexpression of RRL cause the ABA-hypersensitive phenotype in seed germination and seedling growth. (A) Semi-quantitative RT-PCR was performed to assay expression levels of the RRL gene in 5-day-old seedlings of Col-0, OE-4, OE-19, and OE-47 overexpression lines. ACTIN2 gene expression represents the loading control. (B) Seeds were sown on MS medium supplemented or not with 0.3 μM ABA. Photographs were taken at day 5 after stratification. Scale bar=0.5cm. (C) Seeds were sown on MS medium supplemented with 0, 0.3, or 0.5 μM ABA. Germination rates (%) were analysed at day 5 after stratification. Values are the means ±SE of three independent experiments (n=100). *P<0.05 compared with Col-0 control. (D) Seedlings grew 10 d after transfer from MS medium to MS medium supplemented with 0, 5, 10, 20, or 40 μM ABA. Seedlings were transferred from ABA-free medium to ABA-containing medium 48h after stratification. Scale bar=1cm. (E) Primary root lengths were assayed at day 10 after transfer. Values are the means ±SE of three independent experiments (n=50). *P<0.05 compared with Col-0 control. (This figure is available in colour at JXB online.)
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Figure 3: Overexpression of RRL cause the ABA-hypersensitive phenotype in seed germination and seedling growth. (A) Semi-quantitative RT-PCR was performed to assay expression levels of the RRL gene in 5-day-old seedlings of Col-0, OE-4, OE-19, and OE-47 overexpression lines. ACTIN2 gene expression represents the loading control. (B) Seeds were sown on MS medium supplemented or not with 0.3 μM ABA. Photographs were taken at day 5 after stratification. Scale bar=0.5cm. (C) Seeds were sown on MS medium supplemented with 0, 0.3, or 0.5 μM ABA. Germination rates (%) were analysed at day 5 after stratification. Values are the means ±SE of three independent experiments (n=100). *P<0.05 compared with Col-0 control. (D) Seedlings grew 10 d after transfer from MS medium to MS medium supplemented with 0, 5, 10, 20, or 40 μM ABA. Seedlings were transferred from ABA-free medium to ABA-containing medium 48h after stratification. Scale bar=1cm. (E) Primary root lengths were assayed at day 10 after transfer. Values are the means ±SE of three independent experiments (n=50). *P<0.05 compared with Col-0 control. (This figure is available in colour at JXB online.)

Mentions: Fifty independent transgenic plants overexpressing RRL in the Col-0 background were generated. Homozygous T3 lines (OE-4, OE-19, and OE-47) with higher levels of RRL transcripts were selected and their responses to ABA were investigated (Fig. 3A). Seed germination and primary root growth assays were carried out in these overexpression lines to examine their responses to ABA. Taking OE-4 as an example, only ~48% (46–50%) and ~23% (20–25%) of OE-4 seeds germinated and grew green cotyledons, whereas the germination rate of Col-0 seeds was ~99% (99–100%) and ~61% (59–64%) when germinated on MS medium supplemented with 1% sucrose and 0.3 μM or 0.5 μM ABA at day 5 after stratification, respectively. (Fig. 3B, C). In root growth assays, the growth of primary roots was significantly inhibited in MS medium containing >10mM ABA compared with that of Col-0 seedlings. These results suggest that overexpression of RRL caused the increased response to ABA of seed germination and primary root growth.


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)

Overexpression of RRL cause the ABA-hypersensitive phenotype in seed germination and seedling growth. (A) Semi-quantitative RT-PCR was performed to assay expression levels of the RRL gene in 5-day-old seedlings of Col-0, OE-4, OE-19, and OE-47 overexpression lines. ACTIN2 gene expression represents the loading control. (B) Seeds were sown on MS medium supplemented or not with 0.3 μM ABA. Photographs were taken at day 5 after stratification. Scale bar=0.5cm. (C) Seeds were sown on MS medium supplemented with 0, 0.3, or 0.5 μM ABA. Germination rates (%) were analysed at day 5 after stratification. Values are the means ±SE of three independent experiments (n=100). *P<0.05 compared with Col-0 control. (D) Seedlings grew 10 d after transfer from MS medium to MS medium supplemented with 0, 5, 10, 20, or 40 μM ABA. Seedlings were transferred from ABA-free medium to ABA-containing medium 48h after stratification. Scale bar=1cm. (E) Primary root lengths were assayed at day 10 after transfer. Values are the means ±SE of three independent experiments (n=50). *P<0.05 compared with Col-0 control. (This figure is available in colour at JXB online.)
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Figure 3: Overexpression of RRL cause the ABA-hypersensitive phenotype in seed germination and seedling growth. (A) Semi-quantitative RT-PCR was performed to assay expression levels of the RRL gene in 5-day-old seedlings of Col-0, OE-4, OE-19, and OE-47 overexpression lines. ACTIN2 gene expression represents the loading control. (B) Seeds were sown on MS medium supplemented or not with 0.3 μM ABA. Photographs were taken at day 5 after stratification. Scale bar=0.5cm. (C) Seeds were sown on MS medium supplemented with 0, 0.3, or 0.5 μM ABA. Germination rates (%) were analysed at day 5 after stratification. Values are the means ±SE of three independent experiments (n=100). *P<0.05 compared with Col-0 control. (D) Seedlings grew 10 d after transfer from MS medium to MS medium supplemented with 0, 5, 10, 20, or 40 μM ABA. Seedlings were transferred from ABA-free medium to ABA-containing medium 48h after stratification. Scale bar=1cm. (E) Primary root lengths were assayed at day 10 after transfer. Values are the means ±SE of three independent experiments (n=50). *P<0.05 compared with Col-0 control. (This figure is available in colour at JXB online.)
Mentions: Fifty independent transgenic plants overexpressing RRL in the Col-0 background were generated. Homozygous T3 lines (OE-4, OE-19, and OE-47) with higher levels of RRL transcripts were selected and their responses to ABA were investigated (Fig. 3A). Seed germination and primary root growth assays were carried out in these overexpression lines to examine their responses to ABA. Taking OE-4 as an example, only ~48% (46–50%) and ~23% (20–25%) of OE-4 seeds germinated and grew green cotyledons, whereas the germination rate of Col-0 seeds was ~99% (99–100%) and ~61% (59–64%) when germinated on MS medium supplemented with 1% sucrose and 0.3 μM or 0.5 μM ABA at day 5 after stratification, respectively. (Fig. 3B, C). In root growth assays, the growth of primary roots was significantly inhibited in MS medium containing >10mM ABA compared with that of Col-0 seedlings. These results suggest that overexpression of RRL caused the increased response to ABA of seed germination and primary root growth.

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.