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The alternative respiratory pathway is involved in brassinosteroid-induced environmental stress tolerance in Nicotiana benthamiana.

Deng XG, Zhu T, Zhang DW, Lin HH - J. Exp. Bot. (2015)

Bottom Line: Chemical scavenging of H2O2 and virus-induced gene silencing (VIGS) of NbRBOHB compromised the BR-induced alternative respiratory pathway, and this result was further confirmed by NbAOX1 promoter analysis.Furthermore, inhibition of AOX activity by chemical treatment or a VIGS-based approach decreased plant resistance to environmental stresses and compromised BR-induced stress tolerance.Taken together, our results indicate that BR-induced AOX capability might contribute to the avoidance of superfluous reactive oxygen species accumulation and the protection of photosystems under stress conditions in N. benthamiana.

View Article: PubMed Central - PubMed

Affiliation: Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Science, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610064, PR China Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, PR China.

No MeSH data available.


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AOX alleviates photosystem damage in BR-induced stress tolerance. (A, C) Images of the maximum PSII quantum yield (Fv/Fm) (A) and NPQ/4 (C) in the eighth leaf of each N. benthamiana plant under cold (4 °C), 16% PEG 6000, or HL (600 μmol m–2 s–1) stress for 3 d. The alternative pathway was inhibited by 1mM SHAM pre-treatment or NbAOX1 silencing in these BL-treated plants. (B, D) verage values of Fv/Fm (B) and NPQ/4 (D) for the respective chlorophyll fluorescence images. Ten plants were used for each treatment and a picture of one representative leaf is shown. Bars represent mean and standard deviation of values obtained from six independent plants. Significant differences (P<0.05) are denoted by different lowercase letters. (This figure is available in colour at JXB online.)
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Figure 7: AOX alleviates photosystem damage in BR-induced stress tolerance. (A, C) Images of the maximum PSII quantum yield (Fv/Fm) (A) and NPQ/4 (C) in the eighth leaf of each N. benthamiana plant under cold (4 °C), 16% PEG 6000, or HL (600 μmol m–2 s–1) stress for 3 d. The alternative pathway was inhibited by 1mM SHAM pre-treatment or NbAOX1 silencing in these BL-treated plants. (B, D) verage values of Fv/Fm (B) and NPQ/4 (D) for the respective chlorophyll fluorescence images. Ten plants were used for each treatment and a picture of one representative leaf is shown. Bars represent mean and standard deviation of values obtained from six independent plants. Significant differences (P<0.05) are denoted by different lowercase letters. (This figure is available in colour at JXB online.)

Mentions: To determine the role of the AOX pathway in BR-induced stress tolerance, we investigated the function of photosystem II (PSII) under stress conditions, as chlorophyll fluorescence quenching analysis has been proven to be a powerful and reliable method to assess changes in the function of PSII in the steady state of photosynthesis in response to different environmental stresses (Liu et al., 2009). We first analysed the effects of SHAM, an AOX inhibitor, on BR-induced tolerance to cold, PEG, or HL challenge. As shown in Supplementary Fig. S4 (available at JXB online), SHAM (1mM) treatment inhibited 80% of alternative respiration when compared with the control. The results showed that in water-treated plants, the maximum photochemical efficiency of PSII in the dark-adapted state (Fv/Fm) was significantly lower than that in BL-treated plants under stress conditions (Fig. 7A, B). In contrast, NPQ was higher in water-treated plants but lower in BL-treated plants under the same stress conditions for 3 d (Fig. 7C, D). However, BR-induced tolerance to photo-oxidative stress, expressed as Fv/Fm and NPQ, were largely inhibited if the plants were pre-treated with SHAM. To further determine the role of NbAOX1 in BR-induced stress tolerance, we silenced NbAOX1 using VIGS. The silencing effects on TRV:NbAOX1 leaves were confirmed by comparing the expression levels with TRV:00 control leaves (Supplementary Fig. S2). Similar to SHAM pre-treatment, silencing of NbAOX1 inhibited the alternative respiration pathway significantly (Supplementary Fig. S4). Importantly, BL treatment alleviated the significant decline of Fv/Fm and increase of NPQ in TRV:00 plants under stress conditions, and these protective effects were again blocked in TRV:NbAOX1 plants (Fig. 7). These results indicated that BR-induced AOX capacity plays a protective role in plant photosystems against environmental stress.


The alternative respiratory pathway is involved in brassinosteroid-induced environmental stress tolerance in Nicotiana benthamiana.

Deng XG, Zhu T, Zhang DW, Lin HH - J. Exp. Bot. (2015)

AOX alleviates photosystem damage in BR-induced stress tolerance. (A, C) Images of the maximum PSII quantum yield (Fv/Fm) (A) and NPQ/4 (C) in the eighth leaf of each N. benthamiana plant under cold (4 °C), 16% PEG 6000, or HL (600 μmol m–2 s–1) stress for 3 d. The alternative pathway was inhibited by 1mM SHAM pre-treatment or NbAOX1 silencing in these BL-treated plants. (B, D) verage values of Fv/Fm (B) and NPQ/4 (D) for the respective chlorophyll fluorescence images. Ten plants were used for each treatment and a picture of one representative leaf is shown. Bars represent mean and standard deviation of values obtained from six independent plants. Significant differences (P<0.05) are denoted by different lowercase letters. (This figure is available in colour at JXB online.)
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Figure 7: AOX alleviates photosystem damage in BR-induced stress tolerance. (A, C) Images of the maximum PSII quantum yield (Fv/Fm) (A) and NPQ/4 (C) in the eighth leaf of each N. benthamiana plant under cold (4 °C), 16% PEG 6000, or HL (600 μmol m–2 s–1) stress for 3 d. The alternative pathway was inhibited by 1mM SHAM pre-treatment or NbAOX1 silencing in these BL-treated plants. (B, D) verage values of Fv/Fm (B) and NPQ/4 (D) for the respective chlorophyll fluorescence images. Ten plants were used for each treatment and a picture of one representative leaf is shown. Bars represent mean and standard deviation of values obtained from six independent plants. Significant differences (P<0.05) are denoted by different lowercase letters. (This figure is available in colour at JXB online.)
Mentions: To determine the role of the AOX pathway in BR-induced stress tolerance, we investigated the function of photosystem II (PSII) under stress conditions, as chlorophyll fluorescence quenching analysis has been proven to be a powerful and reliable method to assess changes in the function of PSII in the steady state of photosynthesis in response to different environmental stresses (Liu et al., 2009). We first analysed the effects of SHAM, an AOX inhibitor, on BR-induced tolerance to cold, PEG, or HL challenge. As shown in Supplementary Fig. S4 (available at JXB online), SHAM (1mM) treatment inhibited 80% of alternative respiration when compared with the control. The results showed that in water-treated plants, the maximum photochemical efficiency of PSII in the dark-adapted state (Fv/Fm) was significantly lower than that in BL-treated plants under stress conditions (Fig. 7A, B). In contrast, NPQ was higher in water-treated plants but lower in BL-treated plants under the same stress conditions for 3 d (Fig. 7C, D). However, BR-induced tolerance to photo-oxidative stress, expressed as Fv/Fm and NPQ, were largely inhibited if the plants were pre-treated with SHAM. To further determine the role of NbAOX1 in BR-induced stress tolerance, we silenced NbAOX1 using VIGS. The silencing effects on TRV:NbAOX1 leaves were confirmed by comparing the expression levels with TRV:00 control leaves (Supplementary Fig. S2). Similar to SHAM pre-treatment, silencing of NbAOX1 inhibited the alternative respiration pathway significantly (Supplementary Fig. S4). Importantly, BL treatment alleviated the significant decline of Fv/Fm and increase of NPQ in TRV:00 plants under stress conditions, and these protective effects were again blocked in TRV:NbAOX1 plants (Fig. 7). These results indicated that BR-induced AOX capacity plays a protective role in plant photosystems against environmental stress.

Bottom Line: Chemical scavenging of H2O2 and virus-induced gene silencing (VIGS) of NbRBOHB compromised the BR-induced alternative respiratory pathway, and this result was further confirmed by NbAOX1 promoter analysis.Furthermore, inhibition of AOX activity by chemical treatment or a VIGS-based approach decreased plant resistance to environmental stresses and compromised BR-induced stress tolerance.Taken together, our results indicate that BR-induced AOX capability might contribute to the avoidance of superfluous reactive oxygen species accumulation and the protection of photosystems under stress conditions in N. benthamiana.

View Article: PubMed Central - PubMed

Affiliation: Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Science, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610064, PR China Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, PR China.

No MeSH data available.


Related in: MedlinePlus