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Synergistic and Antagonistic Action of Phytochrome (Phy) A and PhyB during Seedling De-Etiolation in Arabidopsis thaliana.

Su L, Hou P, Song M, Zheng X, Guo L, Xiao Y, Yan L, Li W, Yang J - Int J Mol Sci (2015)

Bottom Line: In this work, we compared hypocotyl elongation of the phyA-211 phyB-9 double mutant with the wild type, the phyA-211 and phyB-9 single mutants under different intensities of far-red (FR), red (R), blue (B) and white (W) light.We confirmed that phyA and phyB synergistically promote seedling de-etiolation in B-, B plus R-, W- and high R-light conditions.Gene expression analyses of RBCS members and HY5 suggest that phyB and phyA act antagonistically on seedling development under FR light.

View Article: PubMed Central - PubMed

Affiliation: Maize Research Institute, Sichuan Agricultural University, Chengdu 611130, China. suliang_mp5@163.com.

ABSTRACT
It has been reported that Arabidopsis phytochrome (phy) A and phyB are crucial photoreceptors that display synergistic and antagonistic action during seedling de-etiolation in multiple light signaling pathways. However, the functional relationship between phyA and phyB is not fully understood under different kinds of light and in response to different intensities of such light. In this work, we compared hypocotyl elongation of the phyA-211 phyB-9 double mutant with the wild type, the phyA-211 and phyB-9 single mutants under different intensities of far-red (FR), red (R), blue (B) and white (W) light. We confirmed that phyA and phyB synergistically promote seedling de-etiolation in B-, B plus R-, W- and high R-light conditions. The correlation of endogenous ELONGATED HYPOCOTYL 5 (HY5) protein levels with the trend of hypocotyl elongation of all lines indicate that both phyA and phyB promote seedling photomorphogenesis in a synergistic manner in high-irradiance white light. Gene expression analyses of RBCS members and HY5 suggest that phyB and phyA act antagonistically on seedling development under FR light.

No MeSH data available.


PhyB antagonizes phyA on regulation of seedling development under far-red (FR) light. (A) PhyB shows the antagonistic effect on phyA in regulating seedling de-etiolation responses under different FR intensities. The means of three replicates (at least 30 seedlings each replicate) are shown ± SE; (B) qRT-PCR analysis of PHYA and PHYB transcript levels in the Col-0 wild type during the Dk/FR transition. Seedlings were grown in darkness for four days and then transferred to FR light (2.5 µmol·m−2·s−1) for 10 min to 48 h. Error bars indicate the SD of three replicates; RT-PCR (C) or qRT-PCR (D) analysis of RBCS genes in seedlings of the WT Col-0, and phyA-211, phyB-9 and phyA-211 phyB-9 mutants grown in darkness for 5 days or in darkness for 4 days then transferred to FR light (18.1 μmol·m−2·s−1) for 1 day. RT-PCR of the 18S RNA gene is shown at the bottom as a positive control. Error bars indicate the SD of three replicates; and (E) qRT-PCR analyses of HY5 transcripts in seedlings of the WT Col-0, and phyA-211, phyB-9 and phyA-211 phyB-9 mutants; Seedlings were grown as (A). Error bars indicate the SD of three replicates.
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ijms-16-12199-f004: PhyB antagonizes phyA on regulation of seedling development under far-red (FR) light. (A) PhyB shows the antagonistic effect on phyA in regulating seedling de-etiolation responses under different FR intensities. The means of three replicates (at least 30 seedlings each replicate) are shown ± SE; (B) qRT-PCR analysis of PHYA and PHYB transcript levels in the Col-0 wild type during the Dk/FR transition. Seedlings were grown in darkness for four days and then transferred to FR light (2.5 µmol·m−2·s−1) for 10 min to 48 h. Error bars indicate the SD of three replicates; RT-PCR (C) or qRT-PCR (D) analysis of RBCS genes in seedlings of the WT Col-0, and phyA-211, phyB-9 and phyA-211 phyB-9 mutants grown in darkness for 5 days or in darkness for 4 days then transferred to FR light (18.1 μmol·m−2·s−1) for 1 day. RT-PCR of the 18S RNA gene is shown at the bottom as a positive control. Error bars indicate the SD of three replicates; and (E) qRT-PCR analyses of HY5 transcripts in seedlings of the WT Col-0, and phyA-211, phyB-9 and phyA-211 phyB-9 mutants; Seedlings were grown as (A). Error bars indicate the SD of three replicates.

Mentions: It was previously reported that phyB might be partially involved in FR-HIRs leading to hypocotyl shortening in the phyB-9 mutant [28,29,30,31]. The hypocotyls of the phyA-211 phyB-9 double mutant were shorter than those of the phyA-211 single mutant under FR light (2.5 μmol·m−2·s−1), indicating that there is an antagonistic effect between phyA and phyB [31]. To further investigate whether the antagonistic effect was related to different intensities of FR light, hypocotyl length of the WT, phyA-211, phyB-9 and phyA-211 phyB-9 were measured in response to different intensities of FR light (Figure 4A). No significant difference in hypocotyl length was observed in the phyA-211 mutant in all FR intensities. Despite sharing similar dynamic trend of hypocotyl elongation, the phyB-9 mutant had shorter hypocotyls than the WT Col-0, especially under weak FR intensities (1.0–1.4 μmol·m−2·s−1). In addition, the phyA-211 phyB-9 double mutant seedlings had hypocotyls 7.9%–18.9% shorter than that of the phyA-211 single mutant under different FR intensities, instead of taking the phyA-211 single mutant phenotype.


Synergistic and Antagonistic Action of Phytochrome (Phy) A and PhyB during Seedling De-Etiolation in Arabidopsis thaliana.

Su L, Hou P, Song M, Zheng X, Guo L, Xiao Y, Yan L, Li W, Yang J - Int J Mol Sci (2015)

PhyB antagonizes phyA on regulation of seedling development under far-red (FR) light. (A) PhyB shows the antagonistic effect on phyA in regulating seedling de-etiolation responses under different FR intensities. The means of three replicates (at least 30 seedlings each replicate) are shown ± SE; (B) qRT-PCR analysis of PHYA and PHYB transcript levels in the Col-0 wild type during the Dk/FR transition. Seedlings were grown in darkness for four days and then transferred to FR light (2.5 µmol·m−2·s−1) for 10 min to 48 h. Error bars indicate the SD of three replicates; RT-PCR (C) or qRT-PCR (D) analysis of RBCS genes in seedlings of the WT Col-0, and phyA-211, phyB-9 and phyA-211 phyB-9 mutants grown in darkness for 5 days or in darkness for 4 days then transferred to FR light (18.1 μmol·m−2·s−1) for 1 day. RT-PCR of the 18S RNA gene is shown at the bottom as a positive control. Error bars indicate the SD of three replicates; and (E) qRT-PCR analyses of HY5 transcripts in seedlings of the WT Col-0, and phyA-211, phyB-9 and phyA-211 phyB-9 mutants; Seedlings were grown as (A). Error bars indicate the SD of three replicates.
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ijms-16-12199-f004: PhyB antagonizes phyA on regulation of seedling development under far-red (FR) light. (A) PhyB shows the antagonistic effect on phyA in regulating seedling de-etiolation responses under different FR intensities. The means of three replicates (at least 30 seedlings each replicate) are shown ± SE; (B) qRT-PCR analysis of PHYA and PHYB transcript levels in the Col-0 wild type during the Dk/FR transition. Seedlings were grown in darkness for four days and then transferred to FR light (2.5 µmol·m−2·s−1) for 10 min to 48 h. Error bars indicate the SD of three replicates; RT-PCR (C) or qRT-PCR (D) analysis of RBCS genes in seedlings of the WT Col-0, and phyA-211, phyB-9 and phyA-211 phyB-9 mutants grown in darkness for 5 days or in darkness for 4 days then transferred to FR light (18.1 μmol·m−2·s−1) for 1 day. RT-PCR of the 18S RNA gene is shown at the bottom as a positive control. Error bars indicate the SD of three replicates; and (E) qRT-PCR analyses of HY5 transcripts in seedlings of the WT Col-0, and phyA-211, phyB-9 and phyA-211 phyB-9 mutants; Seedlings were grown as (A). Error bars indicate the SD of three replicates.
Mentions: It was previously reported that phyB might be partially involved in FR-HIRs leading to hypocotyl shortening in the phyB-9 mutant [28,29,30,31]. The hypocotyls of the phyA-211 phyB-9 double mutant were shorter than those of the phyA-211 single mutant under FR light (2.5 μmol·m−2·s−1), indicating that there is an antagonistic effect between phyA and phyB [31]. To further investigate whether the antagonistic effect was related to different intensities of FR light, hypocotyl length of the WT, phyA-211, phyB-9 and phyA-211 phyB-9 were measured in response to different intensities of FR light (Figure 4A). No significant difference in hypocotyl length was observed in the phyA-211 mutant in all FR intensities. Despite sharing similar dynamic trend of hypocotyl elongation, the phyB-9 mutant had shorter hypocotyls than the WT Col-0, especially under weak FR intensities (1.0–1.4 μmol·m−2·s−1). In addition, the phyA-211 phyB-9 double mutant seedlings had hypocotyls 7.9%–18.9% shorter than that of the phyA-211 single mutant under different FR intensities, instead of taking the phyA-211 single mutant phenotype.

Bottom Line: In this work, we compared hypocotyl elongation of the phyA-211 phyB-9 double mutant with the wild type, the phyA-211 and phyB-9 single mutants under different intensities of far-red (FR), red (R), blue (B) and white (W) light.We confirmed that phyA and phyB synergistically promote seedling de-etiolation in B-, B plus R-, W- and high R-light conditions.Gene expression analyses of RBCS members and HY5 suggest that phyB and phyA act antagonistically on seedling development under FR light.

View Article: PubMed Central - PubMed

Affiliation: Maize Research Institute, Sichuan Agricultural University, Chengdu 611130, China. suliang_mp5@163.com.

ABSTRACT
It has been reported that Arabidopsis phytochrome (phy) A and phyB are crucial photoreceptors that display synergistic and antagonistic action during seedling de-etiolation in multiple light signaling pathways. However, the functional relationship between phyA and phyB is not fully understood under different kinds of light and in response to different intensities of such light. In this work, we compared hypocotyl elongation of the phyA-211 phyB-9 double mutant with the wild type, the phyA-211 and phyB-9 single mutants under different intensities of far-red (FR), red (R), blue (B) and white (W) light. We confirmed that phyA and phyB synergistically promote seedling de-etiolation in B-, B plus R-, W- and high R-light conditions. The correlation of endogenous ELONGATED HYPOCOTYL 5 (HY5) protein levels with the trend of hypocotyl elongation of all lines indicate that both phyA and phyB promote seedling photomorphogenesis in a synergistic manner in high-irradiance white light. Gene expression analyses of RBCS members and HY5 suggest that phyB and phyA act antagonistically on seedling development under FR light.

No MeSH data available.